PROC. BIOL. SOC. WASH. 102(4), 1989, pp. 947-959 ALLOCRANGONYCTIDAE AND PSEUDOCRANGONYCTIDAE, TWO NEW FAMILIES OF HOLARCTIC SUBTERRANEAN AMPHIPOD CRUSTACEANS (GAMMARIDEA), WITH COMMENTS ON THEIR PHYLOGENETIC AND ZOOGEOGRAPHIC RELATIONSHIPS John R. Holsinger Abstract. — Two new families of gammaridean amphipod crustaceans, Al-locrangonyctidae and Pseudocrangonyctidae, are described. The former is com-posed of a single genus that occurs in south-central United States; the latter is composed of two genera that occur in northeastern Asia. Members of both families inhabit subterranean fresh waters and are of stygobiont facies. Although the phylogenetic relationship of the allocrangonyctids is unclear, they are ap-parently allied with the genus Pseudoniphargus and may be aberrant hadzioids. The pseudocrangonyctids are allied with the Holarctic family Crangonyctidae and are assigned to the superfamily Crangonyctoidea. The North American amphipod genus Al-locrangonyx Schellenberg, and the east Asian genera Pseudocrangonyx Akatsuka & Ko-mai and Procrangonyx Schellenberg were originally assigned to the Crangonyx group of the old family Gammaridae (s.l.) by Schellenberg (1936). In recent years, how-ever, the Gammaridae have been split into a number of separate families, and many of the genera placed in the Crangonyx group by Schellenberg have been assigned to dif-ferent families. Some of these genera are now placed in the family Crangonyctidae (see Holsinger 1977, 1986a, b), with which Allocrangonyx, Pseudocrangonyx and Pro-crangonyx have sometimes been associated (see Bousfield 1983, Holsinger 1986a, b). Although these genera may be somewhat "crangonyctid-like" in overall similarity, they possess unique character state combi-nations that preclude their membership in this family (see Holsinger 1986a, b). Both Allocrangonyx and Pseudocrangonyx/ Pro-crangonyx have been referred to informally as separate family groups by several workers (Bousfield 1977, 1978, 1982; Holsinger 1977, 1986b), but heretofore neither group has been given formal family status. In this paper, I will show that each group represents a distinct family of gammaridean amphi-pods. Their phylogenetic, zoogeographic and super-familial relationships will also be ex-amined. Allocrangonyctidae, new family Type genus (and only known genus). —Al-locrangonyx Schellenberg, 1936. Diagnosis.— Without eyes or pigment, of stygobiont facies. Body smooth except for few dorsal spines on uronites. Sexually ma-ture male larger than female, with sexually dimorphic uropod 3. Interantennal lobe of head rounded anteriorly, inferior antennal sinus shallow. Antenna 1 longer than 2, ac-cessory flagellum 2-segmented. Antennae lacking calceoli. Mandibles well developed; left lacinia mobilis 4-dentate; molar tritur-ative; palp 3 -segmented. Lower lip with thick inner lobes. Inner plate of maxilla 1 with one apical seta, outer plate with eight or nine unmodified (non-serrate/pectinate) apical spines. Apical margin of outer plate of max-illa 2 uneven (weakly bilobed), with two dis-
Allocrangonyctidae And Pseudocrangonyctidae, 2 New Families Of Holarctic Subterranean Amphipod Crustaceans (Gammaridea), With Comments On Their Phylogenetic And Zoogeographic Relationships
BioStor
