Hesperocranum, Ubick & Platnick, 1991

Ubick & Platnick, 1991, On Hesperocranum, A New Spider Genus from Western North America (Araneae, Liocranidae), American Museum Novitates 3019 (1), pp. 1-12 : 10-11

HESPEROCRANUM , NEW GENUS

TYPE SPECIES: Hesperocranum rothi , new species.

ETYMOLOGY: The generic name is a contraction of hesperos (Greek for western) and Liocranum , and is neuter in gender.

DIAGNOSIS: The presence of numerous pairs of bristles on legs I-III separates specimens of Hesperocranum from other liocranid genera. Although bristles are also known in Liocranum and Mesiotelus (and perhaps Drassinella ), in those genera they are interspersed with typical leg spines. Hesperocranum can be further distinguished from Liocranum and Mesiotelus in lacking recumbent, feathery leg setae, lacking prognathous chelicerae in males, and having a bipartite epigynal hood in females, and from Drassinella in having pectinate tarsal claws and a male palpus possessing a median apophysis and an unmodified femur.

DESCRIPTION: Total length 2.28-4.06. Carapace pyriform in dorsal view, widest between coxae II and III, narrowed opposite palpal insertion, brownish orange; cephalic area rounded, thoracic groove short, longitudinal; ocular area and clypeus with stiff setae, pars thoracica with fine recumbent setae. From above, anterior eye row slightly recurved, posterior row straight; from front, anterior eye row very slightly procurved, posterior row slightly procurved; AME circular, dark, PME almost circular, light; ALE and PLE oval, light; anterior eyes contiguous; PME separated by almost their diameter, closer to PLE and ALE; ALE and PLE separated by less than their radius; MOQ longer than wide in front, wider than long in back; clypeal height subequal to AME radius. Chelicerae geniculate in males, slightly geniculate in females, anterior face with erect setae, fang furrow with three promarginal teeth and two retromarginal denticles. Mouthparts and sternum brownish orange, darker along sternal margins; endites rectangular, with very slight oblique depressions (more prominent in males), each with anterolateral serrula and anteromedian scopula arising from white area; labium wider than long, invaginated at posterolateral corners, with one strong seta on each anterolateral corner; sternum shieldshaped, rebordered, produced between coxae IV, with sclerotized extensions to and between coxae. Leg formula 4123; legs brownish orange; tarsi with two pectinate claws, lacking distinct claw tufts; trochanters not notched; trichobothria long, in two rows on tarsi, one row on metatarsi and tibiae, increasing in length distally. Typical leg spination pattern (only surfaces bearing spines listed): femora: I-IV d1 - 1-0; tibiae: I, II v about 40 pairs of bristles; III v1-2 -2 and about 15 pairs of bristles; IV v1- 2-2, r0- 1-1-0; metatarsi: I, II v about 25 pairs of bristles; III v0-0-2 and about 15 pairs of bristles; IV p1- 0-0, v0- 1-2, r1- 0-0; tarsi: I-III v about 10-15 pairs of bristles. Abdomen dark gray dorsally, grayish-white ventrally, dorsoventrally flattened, oval in dorsal view, anteriorly truncate, widest posteriorly; scutum absent; anterior spinnerets conical, separated by about two-thirds their diameter, two-segmented, distal segment short but distinct; median spinnerets small, slender in males, flattened and longitudinally elongated in females; posterior spinnerets two-segmented, distal segment short. Male palpal femur not modified ventrally; tibia with spinelike retrolateral apophysis and rounded prolateral lobe; tegulum bearing median apophysis, platelike embolus, and membranous conductor. Epigynum longer than wide, with bipartite anterior hood and anterolateral copulatory pores; oval spermathecae and slender, sinuous copulatory ducts present, visible through integument.

NOTE: The existence of this genus was first indicated by Roth (1985) in his key to Nearctic genera of Clubionidae , where it was referred to as an undescribed genus from central California.