Nesticus pecki, Hedin, Marshal & DELLINGER, Bob, 2005

Hedin, Marshal & DELLINGER, Bob, 2005, Descriptions of a new species and previously unknown males of Nesticus (Araneae: Nesticidae) from caves in Eastern North America, with comments on species rarity, Zootaxa 904, pp. 1-19 : 14-17

Nesticus pecki new species

Figs. 1, 17-20

Type Material. Holotype. - Male, U.S.A: Tennessee: Marion County, Monteagle Saltpeter Cave, 6.4 km SE of Monteagle, 35°11' N, 85°46' W, elev. approximately 265 meters, coll. 26 September 1992, M. Hedin, J. Hedin & S. O’Kane ( MCH male specimen #1624 ).

Paratypes. - Female, data as for holotype ( MCH female specimen #1625 ); 2 females, data as for holotype, coll. 29 September 1991, M. Hedin, K. Crandall & A. Gerber ( MCH female specimens #1012, #1013) .

Diagnosis. - Small-bodied spiders with well-developed eyes, a rare condition in Nesticus of the Cumberland Plateau (the only other known taxon with such features is N. carteri Emerton 1875). Males distinguished by dorsal paracymbial process that swings laterally towards the distal paracymbium, split at the base into overlapping translucent processes, the most dorsal process much less broad than the underlying process (Fig. 17). The tegular apophysis is thickened and chisel-like, diverging strongly in an anterior direction (Fig. 18). Medium septum of the epigynum is conspicuously broad, and flares posteriorly (Fig. 19).

Description of male holotype (Figs. 17 & 18; Table 1). - Color of appendages and carapace uniform in coloration, between the HTML colors “orange” (# FFA 500) and "dark orange" (# FF 8 C 00). Abdomen paler, with dark dorsolateral markings towards posterior end. All secondary eyes approximately equal in size, with dark peripheral pigmentation. Principal eyes about one-fifth diameter of secondary eyes, with dark underlying pigmentation. Leg formula 1423. Leg I less than 8 times longer than carapace width. Palp with dorsal paracymbial process that swings laterally towards the distal paracymbium, split at the base into overlapping translucent processes, the most dorsal process much less broad than underlying process. Distal end of paracymbium dark, well-sclerotized, shape approximating an insect mandible. Ventral paracymbium thickened basally. Tegular apophysis dark, thickened, chisel-like, diverging anteriorly. Median apophysis blade-like, overlap- ping tegular apophysis, pointed medially.

Description of female paratype ( MCH female specimen #1625) (Figs. 19 & 20; Table 1). - Female slightly paler than male, uniformly light tan to creamy white, including abdomen. Secondary eyes approximately equal in size, peripheral pigmentation cloudy grey to black. Principal eyes much smaller, perhaps one-tenth diameter of secondary eyes. Leg formula 1423. Leg I less than 8 times longer than carapace width. Epigynum wide, occupying over half width of the abdomen. Medium septum conspicuously broad anteriorly, broadening further posteriorly (i.e., appears to flare). Ear-shaped pockets lateral of median septum, with slender spermathecae beneath and visible at lateral edge.

Variation. - Examination of two other females from the paratype series reveals no significant genitalic differences from the paratype female described.

Natural History. - The male and female specimens collected in 1992 were found in the twilight zone of the main cave passage, approximately 180 meters from the main entrance, in small tangle webs under wooden debris. Spiders collected in 1991 (two females, multiple immatures) were found in the relatively moist, subparallel passage south of the main passage, only 15-30 meters from a second small entrance, hanging inverted in vertically-oriented webs along passage walls.

Distribution. - Known only from the type locality in southeastern Tennessee, along the edge of the Cumberland Plateau (Fig. 1).

DNA sequences. - Mitochondrial 16S (Genbank accession number AF 004654) and nuclear ITS ( AF 003821) DNA sequences were reported in Hedin (1997a), under the species name N. valentinei. This was a misidentification.

Etymology. - Named after Dr. Stewart B. Peck, biospeleologist from Carleton University, Canada, in recognition of his pioneering work on the diversity and evolution of invertebrate cave faunas from the TAG region of the southern Appalachians.