Karos tersum, Cruz-López & Francke, 2015

Cruz-López, Jesús A. & Francke, Oscar F., 2015, Cladistic analysis and taxonomic revision of the genus Karos Goodnight & Goodnight, 1944 (Opiliones, Laniatores, Stygnopsidae), Zoological Journal of the Linnean Society 175 (4), pp. 827-891 : 852-854

KAROS TERSUM SP. NOV.

( FIGS 21–23, 59, 61C, 62A, 63G)

Karos parvus: Goodnight & Goodnight, 1971: 35 (in part).

Type material: MEXICO: San Luís Potosí: ♂ holotype ( CNAN-T0725 ) and 2 ♀ paratypes ( TMM 37.129 ) (39. vii.1970; D. McKenzie), (lat 22.11639°, lon −99.16917°). Municipio Ciudad Valles, La Cueva de la Llanura, 4.8 km W Micos (previously designated as paratypes of Karos parvus by Goodnight & Goodnight, 1971) .

Material examined: MEXICO: San Luís Potosí: 1 ♀ [ CNAN (13.ii.2011; O. Francke, A. Valdez, C. Santibáñez, J. Cruz and G. Contreras)], (21°37′48″N, 99°03′ 38.73″W). Municipio Aquismón, Cueva de El Sol , Mantetzulel .

Etymology: From the Latin tersum (smooth), referring to the reduction in dorsal ornamentation of the scutum.

Diagnosis: Troglomorphic species. Sexual dimorphism of scutum unremarkable ( Fig. 21B). Tubercles of transversal rows III and IV very small, mesotergal area II with only a few central tubercles ( Figs 21C, 63G). Spines of the ocularium small, close to each other but not fused at their bases ( Fig. 22C). Sexual length of femur ratio II: 1.42 and IV: 1.47. Metatarsus II with three clear annuli in males, two in females. Dorsoectal apophyses of coxa IV present, increasing in size distally, similar in both sexes. Male genitalia: apical margin convex. Lateral setae with cylindrical bases, flattened distally. Two pairs of parastylar setae, lateral to follis, basal pair slightly separated from follis base. Spiniform projections barely visible ( Fig. 23).

Description: Male holotype: Measurements: scutum length 3.3, maximum scutum width 2.7. Legs. I 2.00/ 0.75/1.55/2.10/, II 3.55/1.35/3.20/3.50, III 2.45/0.80/ 2.00/2.55, IV 3.90/1.25/3.45/3.80. Dorsum. Eyes slightly pigmented ( Fig. 21B). Dorsum almost smooth, area II with only a few, small central tubercles, complete rows only on areas III and IV, tubercles small, except the central, which is spiniform ( Fig. 63G). Spines of ocularium short, close to each other ( Fig. 22C). Lateral clear areas on scutum triangular-shaped, clear areas on mesotergal area V apices and free tergites I and II, small, spiniform. Venter. Densely covered with spiniform tubercles. Row of tubercles on coxa I longer than those of the other coxae. Coxa IV most densely covered by tubercles. Dorsoectal apophyses of coxa increasing in size distally. Pedipalps. Patella with two mesodistal tubercles. Legs. Ornamentation similar on all legs, covered by small spiniform tubercles ( Fig. 22A). Posterior legs slightly thicker than anterior ones. Metatarsus II with three inconspicuous clear annuli. Femur III curved. Tarsal count 4(2):8(3):6:6. Male genitalia. Apical margin convex. Lateral setae basally cylindrical, distally flattened, basal pair small and ventrally displaced. Parastylar setae lateral to follis. Spiniform projections not exposed, but visible ( Fig. 23). Female paratype: Measurements: scutum length 3.2, maximum scutum width 2.5. Similar to male, with the following differences: mid-bulge shorter, giving scutum appearance of being slightly rectangular, sexual proportion of femora to metatarsi: II 1.42/1.42/1.56/1.52 and IV 1.47/1.78/1.56/1.40 ( Figs 21A, 22A). Metatarsus II with two inconspicuous clear annuli. Tarsal count 4(2):7(3):5– 6:6.

Natural history: The female collected in ‘Cueva de El Sol, Mantetzulel’ did not exhibit thanatosis behaviour, unlike other stygnopsids ( Cruz-López & Francke, 2013a, b).

Taxonomic accounts: Goodnight & Goodnight (1971) designated some specimens as paratypes of Karos parvus from localities other than the type locality, which proved to be incorrect. Karos tersum sp. nov. is one of these incorrectly ‘paratyped’ samples, and it is clearly different from Karos parvus . The new species is troglomorphic and quite pale in colour, has an almost smooth dorsum, and has the spines of the ocularium close to each other at the bases.