Chisosa, HUBER, 2000

HUBER, BERNHARD A., 2000, New World Pholcid Spiders (Araneae: Pholcidae): A Revision At Generic Level, Bulletin of the American Museum of Natural History 2000 (254), pp. 1-348 : 124-125

CHISOSA , NEW GENUS

TYPE SPECIES: Pholcophora diluta Gertsch and Mulaik, 1941 .

ETYMOLOGY: The generic name is derived from the Chisos Mountains in Big Bend National Park, Texas. Gender feminine.

DIAGNOSIS: Tiny pholcids (total length ~ 1.2–1.4 mm) with short legs, globular opisthosoma, without thoracic groove, with eight eyes, stridulatory ridges on male chelicerae; distinguished from other North American short-legged genera ( Pholcophora , Tolteca ) by the distally enlarged male palpal femur and the large and complex procursus.

DESCRIPTION: Total length ~ 1.2–1.4 mm.

Carapace light ochre, without thoracic groove; ocular area hardly elevated (fig. 478), with eight eyes, AME only slightly smaller than others (fig. 481); distance PME- ALE small (~ 25% of PME diameter). Male clypeus unmodified. Male chelicerae with one ( C. diluta ) or two ( C. baja ) pairs of frontal apophyses, with stridulatory ridges laterally. Sternum without anterior humps. Male palpal coxa without retrolateral apophysis, femur relatively large, conspicuously widened distally; procursus relatively large and complicated. Tarsal organ exposed (examined: C. diluta ). Bulb with relatively simple embolar division. Legs short (leg 1 about 3 3.5 × body length; tibia 1 l/d: 14 21), leg formula 1423 in C. diluta , 4123 in C. baja ; legs without spines, without curved and vertical hairs; retrolateral trichobothrium on tibia 1 very distal (at 63% in C. diluta , not seen in C. baja ); tarsus 1 with ~ 5 pseudosegments. Opisthosoma globular, monochromous; male epigastric system not examined; ALS with piriform gland spigots (examined: C. diluta female: fig. 151). Sexual dimorphism slight ( C. baja female unknown).

MONOPHYLY: The two species included share the complex, large procursus and the distally widened male palpal femur.

GENERIC RELATIONSHIPS: The genus may be close to several other genera of short-legged pholcids with globular opisthosoma, especially with Tolteca which is similar in habitus and geographically close, and with Aucana (a mainly Chilean genus!), which shares the exposed tarsal organ and the absence of epiandrous spigots.

DISTRIBUTION/COMPOSITION: Only two species described, from Texas ( USA), and Baja California Norte ( Mexico).

Chisosa diluta (Gertsch and Mulaik, 1941) ,