Vol. 105, No. 3, May & June, 1994 125 A NEW SPECIES OF HELIUS CRANE FLY (DIPTERA: TIPULIDAE) WITH REDUCED ANTENNAE, FROM ARIPO CAVES, TRINIDAD* Nathan Welch, 2 Jon K. Celhaus 3 ABSTRACT: A new species of crane fly, Helius (Helius) darlingtonae, is described from Aripo Caves, Trinidad. Both sexes possess a single segmented antennal flagellum, a fea-ture unique within the Tipulidae, and of rare occurrence within the Diptera in general. Helius darlingtonae n. sp. is apparently an obligate cave dweller, the first noted in this habi-tat for this genus in the New World and the first species in the genus recorded from Trinidad. Based on characteristics of the male genitalia, //. darlingtonae n. sp. appears most similar to H. distinervis Alexander from Panama. The crane fly genus Helius consists of approximately 215 described species worldwide, most of these found in tropical regions. In the neo-tropics alone, 45 species and subspecies have been recorded (Alexander and Alexander 1970, Alexander 1971a, b, 1980). The genus is currently placed in the tribe Limoniini, and is recognized in the adult stage by the distinct and moderately elongate rostrum (about as long as head or longer) and lack of an R2 crossvein (Alexander and Byers 1981). A recent cladistic analysis, based on characters of the immature stages, places Helius not in the Limoniini but as a sister taxon to a clade con-taining the Limoniini, subfamilies Cylindrotominae and Tipulinae and several other genera combined (Oosterbroek and Theowald 1991). Several north temperate species have been reared from aquatic and semi-aquatic habitats, mainly in or around marshy areas (Alexander 1920, Brindle 1967, Byers 1984). In addition, Helius albitarsis (Osten Sacken) emerged in a trap set over a small Puerto Rican stream (Liv-ingston and Gelhaus, 1993) and larvae tentatively identified as Helius were collected from the water in bamboo internodes in Peru (Louton ct a/., in press). Although virtually nothing is known of the adult habitat of the vast majority of species (some exceptions for nearctic species include Rogers 1942, and Zalom 1979), three species in Southeast Asia have been reported from caves, one collected at some distance from the cave entrance (Alexander 1961). We describe in this paper a new species col-lected from Aripo Caves, Trinidad, which shows a remarkable reduction 1 Received September 9, 1993. Accepted October 3, 1993. 2 7213 Boyer Street, Philadelphia, PA 191 19. -Department of Entomology, Academy of Natural Sciences. 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103-1 195. Send reprint requests to second author. ENT. NEWS 105(3): 125-132, Mav & June. 1994
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