Leptocheiridium, Mahnert & Schmidl, 2011

Mahnert, Volker & Schmidl, Jürgen, 2011, First record of the subfamily Pycnocheiridiinae from South America, with the description of Leptocheiridium pfeiferae gen. n., sp. n. (Arachnida: Pseudoscorpiones: Cheiridiidae), Revue suisse de Zoologie 118 (4), pp. 659-666 : 660-661

Leptocheiridium gen. n.

DIAGNOSIS: Member of Cheiridiidae , subfamily Pycnocheiridiinae . Tegument normally sclerotized, vestitural setae of carapace, tergites and pedipalps strongly broadened, leaf-like. Carapace subtriangular, with one pair of eyes, two distinct transverse furrows, the subbasal one flattened, metazone narrow. Most tergites divided, with unmodified lateral borders. Manducatory process rounded, with two marginal setae. Sternites IV to X divided, XI undivided; anal cone with 2 dorsal and 2 acute ventral setae and located between tergite XI and sternite XI; male genitalia of typical cheiridiid morphology (lateral sacs long, well developed, atrium of ejaculatory canal well developed, median genital sac short), female genitalia consisting of three major cribrate plates, the lateral ones more sclerotized than the larger median one. Pleural membrane striate, partly covered with granula. Chelicera with 5 setae on hand; galea short, distinct apical rami present only in female, subgaleal seta near galea base, rallum with three setae, the distal one with a few fine denticles on anterior margin. Pedipalps coarsely granular, hand nearly parallel-sided; teeth on both fingers mostly acute and contiguous; fixed finger with 8 trichobothria (all situated in basal half of finger), movable finger with 2 trichobothria (b and t); long venom duct present in both fingers. Coxae IV much wider than coxae I. Leg I: femur distinctly longer than patella and with articulation, tarsal segments fused, without visible suture. Leg IV: femur much shorter than patella, suture nearly vertical, tarsal segments fused, without visible suture, no tactile tarsal seta; undivided arolia shorter than smooth claws.

TYPE SPECIES: Leptocheiridium pfeiferae sp. n .

ETYMOLOGY: The genus name is a combination of Cheiridium with the Greek adjective “leptos” (thin, slender), referring to the slender pedipalps.

AFFINITIES: Leptocheiridium gen. n. is distinguished from Pycnocheiridium by its slender pedipalps, the distinct transverse furrows on its carapace, the presence of 5 setae on its cheliceral hand, the female galea with 6 apical/subapical rami, and the three sub-equal setae of its rallum (in Pycnocheiridium the anterior seta is distinctly larger: Judson, 1992).

REMARKS: As currently defined, the subfamily Cheiridiinae of the Cheiridiidae , is characterized by having a reduced number of trichobothria on fixed (at most 7) and movable (at most 2) chelal fingers, by the fused femur and patella of leg I and the at least partly fused femur+patella of leg IV; coxa of leg IV also in females unmodified, not enlarged; carapace with two distinct transverse furrows, with depressed metazone (except in Apocheiridium ), and two eyes; cheliceral hand with 4 setae; first seta of rallum enlarged.

The subfamily Pycnocheiridiinae differs from the Cheiridiinae by having femur and patella of leg I well separated and articulated, femur+patella of leg IV with distinct, nearly vertical suture, and eight trichobothria on the fixed chelal finger. Considering these differences, the Pycnocheiridiinae may even deserve familiar rank.

The new genus Leptocheiridium gen. n. confirms the main subfamiliar characters, but differs by the following: number of setae on cheliceral hand (4 vs 5) and morphology of rallum (3 setae, the first one not enlarged), which are probably of generic, but not of subfamiliar importance.