PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON 108(2):266-280. 1995. Description of the ghost shrimp Sergio mericeae, a new species from south Florida, with reexamination of S. guassutinga (Crustacea: Decapoda: Callianassidae) Raymond B. Manning and Darryl L. Felder (RBM) Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C. 20560, U.S.A.; (DLF) Department of Biology, University of Southwestern Louisiana, Lafayette, Louisiana 70504, U.S.A. Abstract.— Sergio mericeae is here described from intertidal sandflats of the Atlantic coast of Florida, where it shares habitats with Neocallichirus rathbunae and A^. grandimana. This new species, formerly identified with the Brazilian species, Sergio guassutinga (until recently assigned to Neocallichirus), bears a strong resemblance to its Brazilian counterpart in body size, the unique dactylar dentition of the major chela, and most other morphological features. However, these apparent sibling species can be distinguished on the basis of body col- oration and subtle but consistent differences in the third maxilliped and major cheliped. Immature specimens from Louisiana, Texas and Tamaulipas, Mexico, strongly resemble topotypic juveniles from Fort Pierce, Florida, and suggest that S. mericeae ranges into the western Gulf of Mexico. Uniqueness of the species described be- low was recognized in the course of our on- going effort to document diversity of in- faunal decapods inhabiting intertidal sub- strates of the Indian River Lagoon on the Atlantic coast of Florida. Our collecting ef- forts in this region of marked tropical to warm-temperate faunal transitions have employed yabby pumps (Hailstone «& Ste- phenson 1961, Manning 1975) for extrac- tion of a speciose assemblage of thalassinid ghost shrimp and associated fossorial forms. Materials from this region have led to com- parative studies of thalassinids from throughout the western Atlantic, as well as systematic revisions and new distribution records, especially for members of the Cal- lianassidae (Felder & Manning 1994; Man- ning 1987, 1993; Manning & Felder 1986, 1991, 1992; Manning & Heard 1986; Man- ning & Lemaitre 1994; Rodrigues & Man- ning 1992). Collection of new materials from Florida was essential in order for us to re- examine the populations previously report- ed on by Biffar (1971), as many specimens upon which his earlier records were based were lost in a laboratory fire just prior to publication of his work. Recent studies of the American Calli- anassidae have revealed a number of cases where species formerly thought to be of wide distribution were actually complexes com- prised of regionally endemized species (Felder et al. 1 99 1 , Felder & Manning 1 994, Felder & Rodrigues 1993, Manning 1993). In the context of those patterns, the previ- ous report of the Brazilian Callianassa guassutinga Rodrigues from south Florida (Biffar 1971) suggested such an extensive range that we were led to question the con- specific assignment of its northern and southern populations. As materials that Bif- far assigned to this species from Florida were for the most part destroyed in the afore- mentioned fire (see Biffar 1971), detailed comparisons with the Brazilian form were delayed until we could accumulate an ad- equate series of adult specimens from the VOLUME 108, NUMBER 2 267 Rorida population. In the course of making those collections, we photographically doc- umented coloration in northern popula- tions which differed markedly from report- ed coloration of the Brazilian species (Ro- drigues 1966, 1971), and this further en- couraged us to undertake detailed morphological studies and the present de- scription of a new species. Material examined is listed by location followed by date, collector (coll), number of specimens per sex and condition (mutl = mutilated, ov = ovigerous, immat = im- mature), and museum number. Size is ex- pressed as postorbital carapace length (cl) or total length (tl) measured in millimeters (mm). The holotype and some paratypes of Sergio mericeae have been deposited in the National Museum of Natural History (USNM), Smithsonian Institution, Wash- ington, DC. Paratypes have been deposited in the University of Southwestern Louisi- ana Zoological Collections (USLZ), Lafa- yette, Louisiana, the Harbor Branch Ocean- ographic Museum (HBOM; formerly the In- dian River Coastal Zone Museum, (IRCZM), Fort Pierce, Florida, and the Florida Marine Research Institute Inver- tebrate Collection (FSBC-I), St. Petersburg, Florida. Comparisons with the Brazilian species Sergio guassutinga were based upon the published figures and descriptions by Rodrigues (1966, 1971) and examination of a mature female from Aracaju, Brazil (USNM 268644), herein illustrated, as well as comparisons with a female topotype (USNM 221802), a male paratype (USNM 256886), a male from Praia de Pirangi-Sul, Rio Grande do Norte, Brazil (USNM 221810), and a female specimen from Na- tal, Rio Grande do Norte, Brazil (USNM 221804). Sergio Manning & Lemaitre, 1994 Sergio mericeae, new species Figs, la-f, 2a-f, 3a-f, 4a-f, 5a-g Callianassa guassutinga. — Biffar, 1971:651, 653, 674, figs. 9, 10 [Virgina Key, Miami, Florida. Not Callianassa guassutinga Ro- drigues, 1966, 1971].-Abele & Kim, 1986: vii, 26, 294, 296, 298, figs, a-c on 299. -Williams et al., 1989: 28, 61. "near Callianassa guassutinga'\— Manning &Felder, 1989: 16. Callianassa (nr. C guassutinga).— Rabalais etal., 1989: 35. Sergio sp.-Staton & Felder, 1995: 505. Sergio guassutinga. —Manning & Lemaitre, 1994: 40 [Florida record only. Not listed and figured Brazilian materials]. Type material —Holotype: North side of Fort Pierce Inlet, Florida, island immedi- ately west of Coon Island, St. Lucie County, Indian River Lagoon, intertidal sandflat just shoreward of sparse seagrass, 27°28.2'N, 80°18.8'W, 20 May 1994, coll D. L. Felder and W. D. Lee, 1 5 (cl 29.8 mm), USNM 268645. Paratypes: Same site as holotype, 6 Mar 1985, coll W. D. Lee and S. Petry, 1 6 (cl 28.3 mm; tl 106 mm), USNM 268682; 5 Mar 1985, coll W. D. Lee and S. Petry, 1 mutl S (cl ca 30 mm), USNM 268683; no date, coll W. D. Lee and S. Petry, 1 9 (cl 31.1 mm; tl 1 1 5 mm), USNM 268684; north side of Fort Pierce Inlet, Florida, Dynamite Point site near Fort Pierce Inlet State Park, St. Lucie County, Indian River Lagoon, 27°28.3'N, 80n7.8'W, 12 Aug 1989 (RBM station FP 89-5), coll D. L. Felder and R. Brown, 1 5 (cl 20.4 mm), USNM 268685; 3 Jun 1993, coll D. L. Felder, 1 $ (cl 10.7 mm; tl 35.8 mm), USLZ 3542; north side of Fort Pierce Inlet, Florida, Coon Island, St. Lucie County, Indian River Lagoon, 27°28.2'N, 80°18.2'W, 3 Apr 1985, coll W. D. Lee and S. Petry, 1 c5 (cl 31.1 mm; tl 115.2 mm), USNM 268686; 16 Jul 1994, coll W. D. Lee, 1 9 (cl 27.1 mm; tl 105.6 mm), USLZ 3543; north side of Fort Pierce Inlet, Florida, northeast of Coast Guard Sta- tion, near exposed sand bar, 0.3 m depth, 25 Apr 1972, coll H. B. Russell, 1 d (cl 29.7 mm; tl 1 1 8 mm), HBOM 89:103; south side of Fort Pierce Inlet, Florida, intertidal sand bar just north of and separated by shallow channel from U.S. Highway AlA causeway 268 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON between Fort Pierce and South Hutchinson Island, St. Lucie County, Indian River La- goon, 27°27.7'N, 80°18.7'W, 23 Jul 1985 (RBM station FP 85-4), coll R. B. Manning and D. L. Felder, 1 mutl 2 (cl ca. 29 mm), USNM 268687; 12 Aug 1986 (RBM station FP 86-4), coll R. B. Manning, D. L. Felder, and W. D. Lee, 1 mutl 6, USNM 268688; 15 Aug 1986 (RBM station FP 86-7), coll R. B. Manning, D. L. Felder, and W. D. Lee, 1 mutl (5 (cl 13.7 mm), 2 ov 22 (1 mutl, other cl 30.5 mm; tl 114.9 mm), USNM 268689; 2 Mar 1987 (RBM station FP 87- 2), coll R. B. Manning and W. D. Lee, 2 SS male (cl 9.1, 9.4 mm), USNM 268690; 3 Mar 1987 (RBM station FP 87-4), coll R. B. Manning and W. D. Lee, 1 mutl 2, USNM 268691; 5 Mar 1987 (RBM station FP 87- 6), coll R. B. Manning and W. D. Lee, 2 $6 (cl 10.4, 17.5 mm), USNM 268692; 17 Apr 1988 (RBM station FP 88-1), coll R. B. Manning and M. Schotte, 1 mutl 6 (cl ca. 15 mm), USNM 268693; 1 Jun 1993, coll D. L. Felder, 1 2 (cl 26.5 mm, dissected for hindgut study), USLZ 3544; 2 Jun 1993, coll D. L. Felder, 1 S (cl 12.3 mm, dissected for hindgut study), USLZ 3545; 6 Aug 1 993, coll D. L. Felder and J. M. Felder, 1 2 (cl 14.0 mm), USLZ 3546; St. Lucie, Rorida, intertidal un vegetated sand flat just inside St. Lucie Inlet, Martin County, Indian Riv- er Lagoon, 27°10.5'N, 80°10.4'W, 11 Feb 1983 (RBM station FP 83-2), coll R. B. Manning, W. D. Lee, and H. Schiff; 3 66 (cl 8.3, 9.2, 10.2 mm), USNM 268694; Lake Worth Inlet, Florida, intertidal, sparsely vegetated, sandy to shelly-sand flats on north side of Peanut Island, Palm Beach County, 26°46.7'N, 80°2.9'W, 4 Mar 1987 (RBM station FP 87-5), coll R. B. Manning and W. D. Lee, 3 22 (cl 10.6, 18.7, 30.0 mm), USNM 268695; 10 Aug 1987 (RBM station 87-8), coll D. L. Felder, W. D. Lee, P. Mik- kelsen, and R. Bieler, 1 6 (cl 12.5 mm), USNM 268696; 1 1 Aug 1987 (RBM station 87-9), con D. L. Felder and W. D. Lee, 2 66 (1 mutl, other cl 27.2 mm), USNM 268697; 12 Aug 1987 (RBM station 87-10), coll D. L. Felder, W. D. Lee, and P. Mik- kelsen, 1 6 (cl 17.0 mm), USNM 268698; 1 6 (cl 14.5 mm, photographic voucher), USLZ 3547, 2 66 (cl 13.4, 13.8 mm), 2 mutl ov 22, FSBC-I 47980; 8 Sep 1985, coll W. Lee and P. Mikkelsen, 1 6 (cl 16.0 mm), USNM 268699; 23 July 1994, coll D. L. Felder, J. M. Felder, R. D. Felder, and W. D. Lee, 2 22 (cl 1 1 .9, 18.5 mm), USLZ 3548; Seaquarium Flats, Virginia Key, Dade County, Florida, 29 Feb 1964, coll S. Dob- kin, 1 2 (cl 10.3 mm; tl 37.4 mm), USNM 122732. Other material examined. —Louisiana: Just off" Cat Island Pass, mouth of Terre- bonne Bay, 28°56.8'N, 90°33.7'W, trawl, depth of 12-13 m, 12 Jul 1984, coll N. N. Rabalais and students, 5 mutl immat (cl 6.5-7.9 mm), USLZ 3549. Texas: Port Is- abel, Texas, lower Laguna Madre near Braz- os Santiago inlet, muddy sand flat just north of mainland end of old abandoned cause- way to South Padre Island, Cameron Coun- ty, Jul 1991, coll D. L. Felder, J. M. Felder and R. D. Felder, 1 mutl 2 (cl 10.4 mm), USLZ 3550. Mexico: Barra del Tordo, Ta- maulipas, Mexico, depth ca. 0.3 m, margins of sandy Halodule flat just inside inlet at mouth of Rio Carrizal estuary, 24 May 1982, coll D. L. Felder and R. K. Tinnin, 5 66 (cl 9.5, 9.7, 9.9, 10.6, 12.0 mm), 3 22 (cl 9.5, 10.6, 10.8), USLZ 3551 (two are photo- graphic vouchers). Diagnosis. —Front of carapace with three small spinous anterior projections, usually subequal or with medial slightly longer than laterals. Eyestalks broad, tapered over length, usually terminated in spine, tubercle or acute angle, often not reaching to distal end of first antennular segment. Third max- illiped with dactyl arched and propodus broad, height of propodus greater than length of dactyl; diagonal length of merus-ischium less than or equal to 2 times width at joint between these articles. Major cheliped of adults with inferior margin of merus armed proximally by elongate process of 2-3 fused spines, beyond which is short gap in mar- VOLUME 108, NUMBER 2 269 ginal dentition, lateral surface with low, rounded longitudinal carina; carpus about half as long as palm; dactylus shorter than palm, cutting edge with rectangular tooth proximally, acute recurved tooth at mid- length, and series of smaller acute teeth dis- tally. Minor cheliped with dactylus usually longer than palm. Uropodal exopod with dorsal plate much shorter than ventral plate. Telson with posterior margin weakly emar- ginate. Description.— Adults of relatively large size, with postorbital carapace lengths sometimes >30 mm and total lengths oc- casionally > 1 10 mm. Frontal margin of carapace (Figs, la, 5a, b) with three anterior prominences, each acute or terminated by short spine, median of which is slightly more produced on tri- angular base to form rostrum, lateral of which overlie inner margins of antennal pe- duncles; low, obtuse tooth on anterolateral margin just lateral to outer margin of an- tennal peduncle. Rostrum extending less than V3 visible length of eyestalks in dorsal view. Carapace lacking rostral carina, with distinct linea thalassinica, and with a de- fined dorsal oval marked posteriorly by deep transverse cardiac furrow, furrow extending anteroventrally to either side above linea thalassinica as shallow sinuous groove de- marcating posterior half of dorsal oval. Shallow cervical groove originating imme- diately below linea thalassinica on anterior half of branchiostegite and curved antero- ventrally, intersecting raised sinuous ridge in anterior third of branchiostegite; portion of ridge anterior to intersection positioned ventrolaterally to rounded hepatic boss and usually sculpted by weak crenelations on upper surface. Subantennular region of ep- istome with dense tuft of long setae brack- eting those of antennular peduncle. Eyestalks flattened, weakly concave dor- sally, length equal to or slightly less than 2 times basal width, in dorsal view tips reach- ing to or nearly to distal end of basal an- tennal article; mesial surfaces of eyestalks closely opposed over proximal portion of midline, divergent terminally; weakly sin- uous anterolateral margin arching from broad base of eyestalk to anterior taper, joining mesial margin anteriorly in variable terminus, ending as spinule, tubercle or acute comer; rarely with subterminal spinule or tubercle in addition to terminal one. Cornea dark, area of pigmentation sexually dimor- phic; in both sexes, rounded corneal surface is small, subterminal, anterolateral in po- sition, larger relative to eyestalk and more bulbous in immature than in adult animals; in adult males, pigmented area large, often diffuse, almost broad as stalk, often occu- pying much of distal third to % of eyestalk; in adult females and juveniles, pigmented area smaller, more restricted to area of rounded corneal surface. Antennular peduncle shorter and heavier than antennal peduncle, terminal article slightly longer than penultimate and reach- ing to or beyond midlength of terminal ar- ticle on antennal peduncle; penultimate and terminal articles of peduncle with ven- tromesial and ventrolateral rows of long se- tae, those of ventrolateral row longer, dens- er, and continued onto ventral ramus of fla- gellum; rami of flagellum subequal in length, 4-5 times length of terminal article of pe- duncle; dorsal ramus with sparse tufts of long setae, distal half with heavier articles bearing dense tufts of short ventral setae, articles comprising tapered tip with dense line of short ventral aesthetascs. Antennal peduncle with penultimate article subequal to or slightly longer than terminal article; basal article with dorsolateral carina above laterally produced excretory pore; second article with deep, diagonal ventral suture, distolaterally with single tuft of setae, small rounded vestige of dorsal scale articulated at joint with third article; third article elon- gate, narrower than second, slightly longer than combined lengths of first two, proxi- molaterally with partially fused condylar process articulated to distolateral extreme of second article; fourth article narrower than 270 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON b,d,f,h,i c_ Fig. 1 . Sergio mericeae, new species, type materials from Fort Pierce Inlet, Florida; a-c, f, male holotype (cl 29.8 mm), USNM 268645; d, e, female paratype (cl 26.5 mm), USLZ 3544. a. Carapace front, eyestalks, basal antennal segments, dorsal view, setae not shown; b, Major cheliped of mature male, carpus and chela, external surface; c, Major cheliped of mature male, ischium and merus, external surface; d, Major cheliped of mature female, carpus and chela, external surface; e. Major cheliped of mature female, ischium and merus, external surface; f, Telson, uropods and part of sixth abdominal segment, dorsal view. Sergio guassutinga (Rodrigues) from Aracaju, Brazil, female (cl 23.5 mm), USNM 268644; g, Carapace front, eyestalks, basal antennal segments, dorsal view, setae not shown; h. Major cheliped of mature female, carpus and chela, external surface; i, Major cheliped of mature female, ischium and merus, external surface; j, Telson, uropods and part of sixth abdominal segment, dorsal view. Scale lines indicate 5 mm. VOLUME 108, NUMBER 2 271 third; flagellum 2-2.5 times length of an- tennular flagellum. Mandibles (Fig. 2a) with large, 3 -segmented palp, elongated third article of palp slightly tapered and terminally round- ed, long setae on external and distal surfaces of second article and on proximal extensor surface of third, field of short setae on most of extensor surface and terminal end of third article; incisor process with well-defined, terminally corneous teeth on cutting mar- gin, teeth largest, less coalesced on proximal two thirds of cutting margin, internal sur- face with lip giving rise to molar process proximal to incisor teeth, molar process with 4-6 small marginal teeth; paragnath (not fig- ured) rounded, scaliform, poorly sclero- tized, set against and below molar process. First maxilla (Fig. 2b) with endopodal palp long, narrow, terminal article deflected proximally at articulation; proximal endite densely setose on sinuous margin, terminal lobe additionally with field of large, termi- nally bifurcate setae; distal endite elongate, proximally narrow, broadening terminally where armed with short stiff* bristles and field of short setae, some with bifurcate tips; exopodite low, truncate and setose. Second maxilla (Fig. 2c) with endopod narrowed distally, first and second endites each lon- gitudinally subdivided, internal surface of first endite fused to broad, rounded, mar- ginally setose plate; exopod forming large, broad, scaphognathite. First maxilliped (Fig. 2d) with proximal endite narrowly pro- duced, dentiform, marginally setose; distal endite robust, subquadrate, mesial half of external surface and margins heavily setose, longest setae terminal, internal surface con- cave; exopod ovoid, divided by transverse suture marking notch on mesial margin, longest setae in field on external surface and mesial margin proximal to notch; epipod large, broad, anterior end tapered to narrow terminus. Second maxilliped (Fig. 2e) with long, narrow endopod; endopodal merus length exceeding 4 times width, flexor mar- gin with dense fringe of long, close-set setae; carpus short; propodus slightly arcuate, heaviest distally, length almost 3 times width; dactylus short, about Vs length of propodus, with terminal brush of stiff" bris- tles; exopod phylloform, nearly as long as endopodal merus, marginally fringed by long setae; epipod small, sutures subdividing into 2 proximal lobes and minute trianguliform terminal lobe. Third maxilliped (Figs. 2f, 3a) without exopod; endopod with long, dense setation on mesial margin, terminal 3 articles also with long setation on extensor margins; length of endopodal merus-ischi- um about 2 times width; ischium subquad- rate, slightly longer than broad, diagonal length in adults about 1.6 times width at suture with merus, proximomesial margin forming subacute comer, internal surface with poorly defined, longitudinally oriented elevation bearing curved row of small den- ticles; merus subtriangular, distinctly broader than long; carpus heavy and sub- triangular, with setose lobe on flexor mar- gin, internal surface with dense field of fine setae in distal third; propodus large, subquadrate in adults, height often exceed- ing length, internal surface with narrow me- dian field of fine, dense setae, opposable margin slightly emarginate; dactylus nar- row, arcuate, in adults distinctly shorter than height of propodus, terminally with small brush of stiff" bristles. Branchial formula includes exopods and epipods as described for first and second maxillipeds above; branchiae limited to sin- gle rudimentary arthrobranch on second maxilliped, pair of arthrobranchs on third maxilliped, and pair of arthrobranchs on each of the first through fourth pereopods. First pereopods of two sides forming dis- similar chelipeds, major cheliped heavy, massive in adults of both sexes (Fig. Ib-e), much less altered from minor cheliped in juveniles than in adults (Fig. 5c-f). Major cheliped of adults strongly calcified; ischi- um slender, superior margin weakly sinu- ous, inferior (flexor) margin with row of minute denticles; merus about twice as long 272 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON a,b,c,d,e Fig. 2. Sergio mericeae, new species, type materials from Fort Pierce Inlet, Rorida; a-e, female paratype (cl 26.5 mm), USLZ 3544; f, male holotype (cl 29.8 mm), USNM 268645, right mouthparts. a, Right mandible, external surface; b, First maxilla, external surface; c. Second maxilla, external surface; d. First maxilliped, external surface; e, Second maxilliped, external surface, rudimentary arthrobranch not shown; f, Third maxilliped, internal surface. Scale lines indicate 5 mm. as high, superior margin weakly sinuous, sometimes with few minute tubercles prox- imally, inferior margin more strongly ar- cuate, proximally with strong projecting of- ten bifurcate process of 2-3 fused spines, margin distal to process with short unarmed region beyond which margin is lined by small inferodistally directed teeth; carpus broad, relatively shorter and higher in adults than in immature specimens, in large adults length about %q of height, superior margin nearly straight, forming thin unserrated keel slightly overhanging internal surface, prox- imoinferior margin regularly rounded in outline, serrations of keel most evident on internal surface; propodus heavy, length (in- cluding fixed finger) in large adults about 1.7 times height, height greatest basally, su- perior margin of palm forming unserrated keel, especially in proximal half, inferior VOLUME 108, NUMBER 2 273 Fig. 3. Sergio mericeae, new species, type materials from Fort Pierce Inlet, Florida; a, b, female paratype (cl 26.5 mm), USLZ 3544; c-f, male holotype (cl 29.8 mm) USNM 268645. a. Right third maxilhped, external surface, setae not shown; b. Minor cheliped, internal surface; c. Right second pereopod, external surface; d. Right third pereopod, external surface; e, Right fourth pereopod, external surface; f. Right fifth pereopod, external surface. Sergio guassutinga (Rodrigues) from Aracaju, Brazil, female (cl 23.5 mm), USNM 268644: g, Right third maxilliped, external surface, setae not shown; h. Minor cheliped, internal surface. Scale lines indicate 5 surface with serrated keel most developed proximally, usually with 2-3 sharp short spines or teeth on external surface just prox- imal to gape; fixed finger in adults with pre- hensile margin ranging from strongly serrate to unarmed; dactylus (movable finger) sub- equal in length to palm, prehensile margin at midlength with large, hooked acute tooth bearing a single setose punctum at its base, separated proximally by deep emargination 274 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON from a single heavy, quadrate basal tooth, and distally by another deep emargination from serrate margin on distal third of finger, finger terminated in acute, hooked tip. Minor cheliped (Fig. 3b) slender, elongate in adults; ischium narrow, unarmed; merus elongately ovoid, length subequal to or slightly less than 2 times height, subequal to length of ischium; carpus rectangular, slightly longer than merus, length twice height, smooth; chela about as long as car- pus; palm subrectangular, length slightly ex- ceeding height; fixed finger subequal in length to palm, prehensile margin weakly serrate; dactylus (movable finger) in adults consistently exceeding length of palm, pre- hensile margin very weakly serrate. Second pereopod (Fig. 3c) chelate, patch- es of long setae on inferior margin of ischi- um, most of flexor margin on merus and both margins of carpus lined with evenly spaced long setae, inferior margin of prop- odus with similar long setae proximally, progressively more reduced in length and stiffened distally, subterminally becoming dense patch of short, stiff"bristles; prehensile margins of both fingers corneous, finely and uniformly microserrate along straight edge over most of length in both, microserration terminated distally in thickened corneous tips of fingers; superior margin of dactylus slightly sinuous, with long marginal setation becoming increasingly shorter length dis- tally, replaced by dense patch of short stiff" bristles subterminally; external surface of carpus, propodus and dactylus with scat- tered patches of short setae. Third pereopod (Fig. 3d) merus length about 3 times width; carpus broadest dis- tally, terminally with large patches of long setae overreaching propodus; propodus with strong proximally directed lobe on inferior margin, lobe terminally with long distally directed setae giving way to subdivided tufts of slightly shorter setae along inferodistal margin, superior margin with field of long setae, patterned tufts of lighter setae on out- er face of article; dactylus tear-shaped, ter- minated in slightly comified tip hooked to- ward external side, external surface densely setose, setae arranged in transverse bands on superior half. Fourth pereopod (Fig. 3e) subchelate, in- ferodistal comer of propodus produced to form short fixed finger; soft dense setation on outer surface of propodus and dactylus, that of propodus divided into upper and lower fields, setae slightly longer in lower field which continues onto lower half of in- ternal surface; dactyl terminated in narrow tip hooked toward external side. Fifth pereopod (Fig. 3f) minutely chelate, opposable surfaces of propodus and minute dactylus excavate, spooned, terminally rounded, forming beak-like chela obscured by dense fields of setation on distal Vi of propodus and superior surface of dactylus; corneous prehensile lip of propodus pecti- nate. Anterior abdominal somites smooth dor- sally, surface sculpture of third through fifth tergites progressively more pitted, eroded, or undulated in appearance; second tergite with tuft of long setae on posterolateral lobe; third through fifth tergites each with a small broadly transverse field of very soft dense setae on the lateral lobe; sixth with distinct transverse, terminal, posteriorly facing groove above telson. First pleopod of male and female unira- mous, composed of 2 articles; in male (Fig. 4a), distal article subequal in length to or slightly shorter than proximal, subdivided into 2 lobes by weak longitudinal furrow, in mature male anterior lobe terminally rounded, posterior lobe terminally acute with tip directed anteroventrally; in female (Fig. 4b) proximal article subequal in length to terminal article, terminal article with weakly produced shoulder just beyond mid- length. Second pleopod of male and female biramous; in male (Fig. 4c), dense setation largely restricted to tufts on lateral margin of exopod, distal extreme of exopod, lateral margin of endopod and appendix masculi- na, appendix masculina weakly separated VOLUME 108, NUMBER 2 275 from and not overreaching end of distal lobe of endopod, no evidence of appendix inter- na; in female (Fig. 4d, e), both rami with long setae, appendix interna small and acutely tapered distally. Third to fifth pleo- pod pairs (Fig. 4f) forming large, posteriorly cupped fans when coupled at mesial mar- gins of endopods; endopod of each subtrian- gular, appendix interna embedded into me- sial margin of endopod. Telson (Figs. If, 5g) broader than long, subhexagonal, broadest at lateral lobes at midlength or in anterior half, posterior emargination producing pair of weak lobes or obtuse posterolateral comers, each ter- minated by a tuft of long setae; dorsal sur- face with low, lightly setose boss near each anterolateral comer, medially with subdi- vided short transverse carina bordered pos- teriorly by line of setae. Uropod with acute, posterolaterally directed spine on protopod, spine overreaching anterolateral margin of endopod; endopod broad, trapezoidal, slightly longer than broad, dorsal surface with tuft of long setae near posterolateral comer, setae of posterior margin longest posterolaterally; exopod with anterodorsal plate falling well short of distal exopod mar- gin, distal edge of plate lined with short, thick spiniform setae grading to thinner lon- ger setae of exopod margin and long stiff, spiniform setae at posterodistal comer of plate, distal margin of exopod with dense fringe of setation, fringe diminished and re- placed by row of short spiniform setae on posterior margin. Size.— Among the materials examined, the largest male (cl 31.1 mm; tl 1 1 5 mm) and largest female (cl 30.7 mm; tl 1 15 mm; ovigerous) were both taken from the im- mediate vicinity of Fort Pierce Inlet, Ror- ida. Eggs on ovigerous specimens are small with sizes (max. diameter) after preserva- tion ranging from 0.58-0.62 mm for im- mature eggs without developed eyespots to 0.62-0.68 mm for more mature eggs with well developed eyespots. Color (from notes and color photographs of live specimens).— Variable and fading quickly to opaque white in alcohol. In life most adult specimens with violet pink to rose pink ground color, occasionally very pale; usually with darker pink to scarlet or orange-red on the chelae, cardiac region of carapace, dorsal tergites of abdominal seg- ments 1-2, mid-dorsal and posterior ex- tremes of abdominal tergites 3-5, telson and uropods. Sixth abdominal tergite usually with 2 faint, reddish longitudinal bands to either side of midline in anterior %. Juve- niles often with striking scarlet red to rosy red coloration almost overall, but also with pigment deepest in same body areas as in- dicated for adults above. Known range and habitat. —Known from intertidal to shallow subtidal in the Indian River Lagoon and along the lower Atlantic coast of Florida, USA, and (on the basis of juveniles only) from coastal Gulf of Mexico localities in Louisiana, south Texas, and Ta- maulipas, Mexico. The single immature specimen of Sergio collected from Maya- guez, Puerto Rico, in 1934 (coll: V. Biaggi, Jr., tl 73 mm, USNM 77462) which was previously reported as S. guassutinga by Bif- far (1971) may or may not be correctly as- signed to that species, but we must defer this determination until additional, fully mature and better preserved materials of that southerly population become available. While most specimens have been taken with yabby pumps from intertidal to shal- low subtidal substrates, specimens from off Louisiana were taken in a trawl deployed at a depth of approximately 12-13 m. In vir- tually all cases, the animals appear to be distributed within or near inlets to the open ocean. In inlets of the Indian River Lagoon, where they burrow alongside Neocallichirus rathbunae, they typically occupy less vege- tated areas of sandbars, often just shoreward of where larger mounds of ejecta mark the burrows of A^. rathbunae. At least in shallow waters, adults of Sergio mericeae appear to have mud-lined burrows with surface open- ings 6-10 mm in diameter, and may or may 276 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON c,d,f Fig. 4. Sergio mericeae, new species, type materials from Fort Pierce Inlet, Rorida; a, c, f, male holotype (cl 29.8 mm), USNM 268645; b, d, e, female paratype (cl 26.5 mm), USLZ 3544. a, Right first pleopod of male, internal surface; b, Right first pleopod of female, lateral surface; c. Right second pleopod of male, posterior surface; d. Right second pleopod of female, posterior surface; e. Right second pleopod of female, distal endopod and appendix interna, posterior surface; f, Right third pleopod, anterior surface. Sergio guassutinga (Rodrigues) from Aracaju, Brazil, female (cl 23.5 mm), USNM 268644: g. Left second pleopod of female, distal endopod and appendix interna, posterior surface. Scale lines indicate 2 mm. not have the burrow opening surrounded by a sand mound. Where mounds do occur, they are small, rarely exceed an elevation of 3-5 cm, and often are of muddier com- position than the surface sand. Substrate cores extracted with yabby pumps in the more densely burrowed areas reveal rela- tively clean surface sands underlain by much muddier strata. Etymology.— This species is named for VOLUME 108, NUMBER 2 277 Fig. 5. Sergio mericeae, new species, juvenile paratypes from Fort Pierce Inlet, Rorida, setae not shown; a, c, d, g, male (cl 8.3 mm), USNM 268694; b, male (cl 10.4 mm), USNM 268692; e, f, female (cl 10.6 mm), USNM 268645. a, Anterior carapace, eyestalks, antennal peduncles of immature male, dorsal view; b, front and eyestalks of immature male; c. Minor chela, internal surface, immature male; d. Major chela, internal surface, immature male; e. Minor chela, external surface, immature female; f. Major chela, external surface, immature female; g, Telson, right uropods, sixth abdominal segment, dorsal view, immature male. Not scaled. our friend and colleague, Dr. Mary E. Rice, Director of the Smithsonian Marine Sta- tion- Link Port, Fort Pierce, Florida, in rec- ognition of both her own substantial con- tributions in the field of marine invertebrate zoology and the generous assistance that she has provided to a large number of students, postdoctoral trainees, and fellow research scientists. Remarks.— \A\iQ other species of the ge- nus Sergio, S. mericeae can be distinguished from members of the closely related genus Neocallichirus on the basis of its relatively shorter and more angular, posteriorly emar- ginate telson and its narrower, more elon- gate uropodal endopods. In Florida, S. mer- iceae often occurs alongside A^. rathbunae, N. grandimanus, and a third (yet to be de- scribed) Neocallichirus sp., all of which are also often reddish or pink in coloration. While mature and intact specimens of these species are readily distinguished from S. mericeae on the basis the major chela, all three of these Neocallichirus species also have broad, subquadrate uropodal endo- pods and a relatively long telson, the pos- terior margin of which is not notably emar- ginate but usually nearly straight or slightly convex in shape. Distinction of 5. mericeae from its south- em equivalent, S. guassutinga, can in ma- ture specimens be based upon several char- acters of the major cheliped. In S. mericeae, the merus of this appendage has a more rounded, less sharply defined longitudinal carina on the external surface and has a more 278 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON produced proximal prominence on the in- ferior margin. In S. mericeae this promi- nence is also offset by a short gap from the remaining dentition of the inferior margin, while in S. guassutinga the dentition is more or less equally spaced in the region just be- yond the prominence, the potential gap be- ing interrupted by one or more sizable teeth. Overall, the dentition of this inferior border in S. mericeae is also more ventrally di- rected than in S. guassutinga, where the marginal teeth in mature specimens are usu- ally either lower or slightly more hooked and are thus directed more distally. The proximal end of superior margin of this ar- ticle in mature specimens also often bears a more defined row of low tubercles in S. mericeae than in S. guassutinga. In the larger mature specimens of S. mer- iceae, the carpus of the major chela is rel- atively shorter and of slightly different shape than in the largest S. guassutinga specimens we have seen; while in the Brazilian speci- mens of S. guassutinga carpal length was greater than Vi the palm length and was nev- er less than Vio of carpal height, in S. mer- iceae the carpal length was about half of the palm length and nearer %q of carpal height. Given this difference in dimensions, the ar- cuate inferior margin of this article in S. mericeae is shorter than in S. guassutinga and semicircular in shape. The somewhat broader third maxilliped in S. mericeae may also serve to distinguish it from S. guassutinga. However, differ- ences in specimen preservation can cause variable shrinkage in the soft internal tis- sues of this appendage, and caution must be used determining article dimensions. As folding and crenelation of the integument were conspicuous in most specimens of S. guassutinga available to us, we briefly soaked the third maxillipeds in water to reinflate them prior to determining dimensions. The length of the merus-ischium (measured as a single unit) is consistently subequal to 2 times its maximum width in S. mericeae, while it is at least 2.2 times its width in S. guassutinga. Similarly, the diagonal length of the ischium alone is 1.6 to 1.7 times its width in S. mericeae, while it consistently exceeds 1.8 times its width in S. guassutin- ga. On the internal surface of the ischium, an elevated row of spines (the crista dent at a) on the internal surface of the ischium, which is moderately developed in S. guassutinga, is much less developed and difficult to dis- cern over part of its length in S. mericeae. The propodus of the third maxilliped also differs in the two species, with the greatest height of this article occurring in its proxi- mal third in S. mericeae. By contrast, great- er development of the inferodistal lobe of the propodus in S. guassutinga usually pro- duces a greatest height near its midlength. Other characters may further serve to dif- ferentiate these species, although they can- not be clearly established with presently limited comparative materials. Shrinkage and distortion in preserved specimens ofS. guassutinga preclude our making of very detailed and quantitative comparisons of eyestalks, nephridiopore sculpture, anterior pleopods and telson, despite some evidence of divergence in morphology of these fea- tures. While sculpture of the male gonopod is often of considerable value in separating of closely related species, and the terminal shape in S. mericeae appears to differ strik- ingly from that illustrated for S. guassutinga by Rodrigues (1971, fig. 56), our close ex- amination of available males for the latter species reveals a very similar gonopodal structure to that we have illustrated for S. mericeae (Fig. 4a, c). In both species the posterior lobe may have a terminally acute tip varying in degree of development with maturity. While the terminal posterior and anterior lobes appear to be slightly more divergent in males of S. guassutinga than in mature males of S. mericeae that we ex- amined, only one of two available males of the former species is a large fully mature specimen, and we cannot therefore account for the range of possible variation in that species. VOLUME 108, NUMBER 2 279 The color in life of S. mericeae, with its bright red chelipeds and overall bright red color is different from that described by Ro- drigues (1971: 207, 209) for S. guassutinga, with the females whitish and the males with a pink abdomen and pink-yellowish larger cheliped in the male. In the Indian River Lagoon, Florida, S. mericeae is almost always taken along with scarlet red commensal polyclad worms, 4- 7 mm in length. In some cases 8-1 2 or more of these commensals are taken with mate- rials extracted from a single host burrow. These are either found moving over surfaces of the captured ghost shrimp or are seen when water and mud extracted from the burrow with the yabby pump are washed over a sieve. The occurrence of these com- mensals in such washings appears to be de- finitive evidence that the burrow contains S. mericeae, as thorough extraction from such burrows never yields other species of callianassids. While we remain uncertain of the generic assignment for this commensal, Rodrigues (1971) has also observed, in ad- dition to clausidiid copepod and reddish ne- mertean commensals, occurrence of an un- described reddish species of the polyclad genus Stylochoplana with S. guassutinga. In both Lake Worth, Rorida, and the Rio Car- rizal Estuary, Tamaulipas, Mexico, burrows of callianassids herewith assigned to S. mer- iceae may also host the pinnotherid crab, Pinnixa cristata Rathbun (see Manning & Felder 1989, Rabalais et al. 1989). Acknowledgments We sincerely thank Sergio de Almeida Rodrigues, Instituto de Biociencias, Uni- versidade de Sao Paulo, Brazil, and Paula M. Mikkelsen, then Curator, Harbor Branch Oceanographic Museum, who provided ac- cess to comparative specimen materials, as well as Mary E. Rice, Director of the Smith- sonian Marine Station at Link Port, who facilitated access to collecting sites and lab- oratory facilities at Fort Pierce, Florida. Among many individuals who assisted with our field collections and laboratory obser- vations, we especially thank J. M. Felder, R. D. Felder, W. D. Lee, L. K. Manning, P. M. Mikkelsen, S. Retry and N. N. Rabalais, S. C. Rabalais, and R. K. Tinnin. We also thank Lilly King Manning for preparation of numerous comparative study sketches and Figure 5 for the present paper. This study was supported through an ongoing program of Smithsonian Marine Station project grants to R. B. Manning and D. L. Felder. Partial support was also provided to D. L. Felder through U.S. Minerals Man- agement Service Cooperative Agreement 1 4- 35-0001-30470, U.S. Fish and Wildlife Ser- vice Cooperative Agreement 14-16-0009- 89-963, Task Order No. 6, and a small grant from the Coypu Foundation. This is con- tribution No. 249 for the Smithsonian Ma- rine Station and contribution No. 48 for the USL Laboratory for Crustacean Research. Literature Cited Abele, L. G., & W. Kim. 1986. An illustrated guide to the marine decapod crustaceans of Florida.— Florida Department of Environmental Regula- tion Technical Series 8(1), Parts 1 and 2:i-xvii, 1-760. Biffar, T. A. 1971. The genus Callianassa (Crustacea, Decapoda, Thalassinidea) in South Florida, with keys to the western Atlantic species. — Bulletin of Marine Science 21(3):637-675. Felder, D. L., & R. B. Manning. 1994. Description of the ghost shrimp Eucalliax mcilhennyi, new species, from South Florida, with reexamination of its known congeners (Crustacea: Decapoda: Callianassidae). — Proceedings of the Biological Society of Washington 107(2):340-353. , & S. de A. Rodrigues. 1993. Reexamination of the ghost shrimp Lepidophthalmus louisi- anensis (Schmitt, 1935) from the northern Gulf of Mexico and comparison to L. sihboia, new species, from Brazil (Decapoda: Thalassinidea: Callianassidae).— Journal of Crustacean Biolo- gy 13(2):357-376. , J. L. Staton, & S. de A. Rodrigues. 1991. Patterns of endemism in the ghost shrimp genus Lepidophthalmus (Crustacea, Decapoda, Calli- anassidae): evidence from morphology, ecology and allozymes. — American Zoologist 31(5): lOlA. 280 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON Hailstone, T.S.,& W.Stephenson. 1961. The biology of Callianassa {Trypaea) austmliensis Dana 1852 (Crustacea, Thalassinidea). — University of Queensland Papers, Department of Zoology l(12):259-285. Manning, R. B. 1975. Two methods for collecting crustaceans in shallow water. — Crustaceana 29(3):317-319. . 1987. Notes on western Atlantic Callianas- sidae (Crustacea: Decapoda: Thalassinidea).— Proceedings of the Biological Society of Wash- ington 100(2):386-401. . 1993. Two new species of A^^oca///c/z/rw5 from the Caribbean Sea (Crustacea: Decapoda: Cal- lianassidae).— Proceedings of the Biological So- ciety of Washington 106(1):106-1 14. , & D. L. Felder. 1986. The status of the cal- lianassid genus Callichirus Stimpson, 1866 (Crustacea: Decapoda: Thalassinidea). — Pro- ceedings of the Biological Society of Washington 99(3):437-443. , & . 1989. The Pinnixa cristata com- plex in the western Atlantic, with descriptions of two new species (Crustacea, Decapoda, Pin- notheridae). — Smithsonian Contributions to Zoology 474:i-iii, 1-26. , & . 1991. Revision of the American Callianassidae (Crustacea: Decapoda: Thalas- sinidea).— Proceedings of the Biological Society of Washington 104:764-792. , & . 1992. Gilvossius, a new genus of callianassid shrimp from the eastern United States (Crustacea: Decapoda: Thalassinidea). — Bulletin of Marine Science 49(1-2) [1991]:558- 561. , 8l R. W. Heard. 1986. Additional records of Callianassa rathbunae from Florida and the Ba- hamas (Crustacea: Decapoda: Callianassi- dae).— Proceedings of the Biological Society of Washington 99:347-349. , & R. Lemaitre. 1994. Sergio, a new genus of ghost shrimp from the Americas (Crustacea: De- capoda: Callianassidae).— Nauplius (Brazil) 1:39-44. Rabalais, S. C, W. M. Pulich, Jr., N. N. Rabalais, D. L. Felder, R. K. Tinnin, & R. D. Kalke. 1989. A biological and physical characterization of the Rio Carrizal estuary, Tamaulipas, Mexico.— Contributions in Marine Science 31:25-37. Rodrigues, S. de A. 1 966. Estudos sobre Callianassa, sistematica, biologia e anatomia. Unpublished Doctoral dissertation, Universidade de Sao Paulo, Brazil. Pp. i-iii, 1-168. . 1971. Mud shrimps of the genus Callianassa Leach from the Brazilian coast (Crustacea, De- capoda).— Arquivos de Zoologia, Sao Paulo 20(3): 19 1-223. , & R. B. Manning. 1992. Two new callianas- sid shrimps from Brazil (Crustacea: Decapoda: Thalassinidea).— Proceedings of the Biological Society of Washington 105:324-330. Staton, J. L., & D. L. Felder. 1 995. Genetic variation in populations of the ghost shrimp genus Cal- lichirus (Crustacea: Decapoda: Thalassinoidea) in the western Atlantic and Gulf of Mexico.— Bulletin of Marine Science 56(2):495-508. Williams, A. B., L. G. Abele, D. L. Felder, H. H. Hobbs, Jr., R. B. Manning, P. A. McLaughlin, & I. Pe- rez-Farfante. 1989. Common and scientific names of aquatic invertebrates from the United States and Canada: Decapod Crustaceans.— American Fisheries Society Special Publication 17:i-vii, 1-77.