Thysanina similis, Lyle & Haddad, 2006

Lyle, Robin & Haddad, Charles R., 2006, A revision of the Afrotropical tracheline sac spider genus Thysanina Simon, 1910 (Araneae: Corinnidae), African Invertebrates 47, pp. 95-116 : 109-111

Thysanina similis sp. n.

Figs 31–35

Etymology: This species name is Latin for ‘similar’, and refers to the similarities found in the genitalia of this species and T. transversa .

Diagnosis: This species can be recognised by its narrow semi-circular hoods of the epigyne. It is unique compared to T. transversa , which has S-shaped spermathecae compared to the globular spermathecae of T. similis . The palp of T. similis has a short embolus and rounded tibial apophysis and a more prominent patellar apophysis than T. transversa . In comparison to the other species, T. similis females have very faded or no chevron markings on the abdomen. This is one of two species in the genus that has regular leg spines, in males and females, in addition to cusps in males.

Description:

Male.

Measurements. CL 1.28–1.55, CW 1.23–1.48, AL 1.8–1.88, AW 1.23–1.35, TL 3.0– 3.5, FL 0.08–0.1, SL 0.85–0.88, SW 0.75–0.83, AME–AME 0.08, AME–ALE 0.05, ALE–ALE 0.30, PME–PME 0.12, PME–PLE 0.10, PLE–PLE 0.49. Length of leg segments (sequence from femur to tarsus, and total): I 1.55+0.7+1.25+0.88+0.63=5.01; II 1.33+0.6+1.08+0.95+0.53=4.49; III 0.93+0.38+0.65+0.78+0.25=2.99; IV 1.63+0.55+ 1.15+1.35+0.53=5.21.

Carapace evenly high, declining sharply at three quarters carapace length; surface smooth, short setae scattered throughout; fovea short, narrow, at two-thirds carapace length; carapace bright orange, dark brown near border.All eyes with dark brown rings; AER strongly procurved, laterals 1.5 times the diameter of medians; clypeus height equal to AME diameter at ALE, equal to slightly more than ALE diameter at AME; AME separated by distance equal to their diameter, AME separated from ALE by 0.5 ALE diameter; PER slightly recurved, lateral eyes slightly larger than medians; PME separated by 1.25 times their diameter, PME separated from PLE by distance equal to PLE diameter. Chelicerae dark brown, lighter at base; scattered long black setae over surface; three well separated promarginal teeth, median tooth largest, distal smallest; two closely situated retromarginal teeth, distal tooth largest. Sternum orange, dark brown at border; surface smooth with scattered short setae. Abdomen broader anteriorly, truncated posteriorly; chevron present, with thin lateral line ending at midpoint of abdomen, unattached transverse branches spread across abdomen; similar to male of T. transversa . Legs I to IV compact, robust; uniform in colour, pale yellow to orange; dense setae ventrally on metatarsi and tarsi of legs I to IV; legs I to IV with uniform grey band arrangement; femora with two close distal bands, patellae covered almost entirely by band, tibiae and metatarsi with single distal and proximal bands. Leg spination: femora: I and II pl 1 do 1, III pl 1 do 1 rl 1, IV do 1 rl 1; patellae spine-less; tibiae: I plv 6 cusps, II plv 3 cusps, IV vt 2; metatarsi: I plv 7 cusps, II plv 8 cusps, III plv 1, IV pl 1 rl 1; tarsi: I plv 5 cusps, II plv 3 cusps ( Fig. 31 ); palpal spination: femora pl 1 do 3, patellae rl 1, tibiae pl 2 do 1, tarsi pl 1. Palp orange-brown throughout; retro-lateral tibial apophysis with a smaller apophysis; prominent retrolateral patellar apophysis; embolus twisted behind a hardened sclerite, similar to T. transversa ( Figs 32, 33 ).

Female.

Measurements: CL 1.43–1.5, CW 1.23–1.33, AL 2.1–2.25, AW 1.0–1.5, TL 3.5–3.7, FL 0.08–0.1, SL 0.88–0.93, SW 0.75–0.8, AME–AME 0.04, AME–ALE 0.03, ALE– ALE 0.28, PME–PME 0.11, PME–PLE 0.08, PLE–PLE 0.46. Length of leg segments (sequence from femur to tarsus, and total): I 1.28+0.65+1.03+0.85+0.53=4.34; II 1.05+ 0.58+0.88+0.8+0.45=3.76; III 0.78+0.33+0.55+0.8+0.45=2.91; IV 1.4+0.55+1+ 1.28+0.3=4.53.

Similar in appearance to male, female larger, colouration lighter; chevron absent; three grey spots dorsally, two situated at pedicel to third abdomen length, third marking medially from two thirds abdomen length to spinnerets. All eyes surrounded by dark rings; AER slightly procurved, clypeus height equal to 0.75 AME diameter; anterior eyes subequal in size; AME separated by 0.5 their diameter, AME separated from ALE by 0.25 AME diameter; PER slightly recurved, eyes subequal in size; PME separated by distance equal to their diameter, PME separated from PLE by distance equal to 0.75 PME diameter. Chelicerae dark orange, with black setae scattered on anterior surface; three promarginal teeth, proximal and median teeth largest, subequal in size, distal tooth smallest; two closely situated retromarginal teeth, subequal in size. Legs I to IV similar in colouration to male, with similar band arrangement; legs less compact, thinner than male. Leg spination: femora: I pl 1, IV rl 1; palpal spination: patellae pl 1 do 1, tibiae pl 2 do 2, tarsi pl 2 plv 1 rlv 1 vt 2. Genital area well sclerotised, dark brown to orange; copulatory openings anterior to midpoint of epigyne, located within narrow semi-circular hoods; spermathecae globular, with terminal receptaculae situated in posterior half of epigyne extending to epigastric fold ( Figs 34, 35 ).

Holotype: ơ ‘ California Academy of Sciences / TANZANIA: Tanga: W Usambara / Mtns.: Mazumbai , station / 4º48.5'S; 38º30'E 1500m / 10—20.xi.1995 around buildings / C.E. Griswold, N. Scharff, D. Ubick //’ ( CAS).

Paratypes: 2^‘ California Academy of Sciences / TANZANIA: Tanga: E Usambara / Mtns.: Amani. Forest / 5º5.7'S; 38º38'E 950m el. / 27.x—9.xi.1995 / C.E. Griswold, N. Scharff, D. Ubick //’ ( CAS) . 1ơ ‘ California Academy of Sciences / TANZANIA: Tanga: E Usambara / Mtns.: Amani, Mbomole Hill / 5º5.7'S; 38º37'E 1000m el. / 5— 8.xi.1995 / C.E. Griswold, N. Scharff, D. Ubick //’ ( CAS) .

Distribution: Currently known only from the Usambara Mountain range, situated in the north-eastern part of Tanzania ( Fig. 41 ).

Natural history: This is the only species that has a distinctive preference for forest habitats. Little is known of its microhabitat preferences.

Figures

Figs 31–35. Thysanina similis sp. n.: (31–33) male: (31) schematic representation of cusp arrangement on legs I and II, (32) left palp, ventral view, (33) left palp, retrolateral view; (34, 35) female: (34) epigyne, ventral view, (35) vulva, dorsal view. Scale bar (Figs 32–35) = 0.1 mm.

Fig. 41. Distribution of Thysanina in the Afrotropical region.