Sason sechellanum Simon, 1898

Marusik, Yuri M. & Gerlach, Justin, 2011, First description of the male of Sason sechellanum Simon, 1898 (Araneae: Barychelidae), Zootaxa 2833, pp. 65-68 : 65-67

Sason sechellanum Simon, 1898

Figs 1–12

S. s. Simon, 1898: 370 (DƤ).

S. s.: Benoit 1978: 407, figs 1A–D (Ƥ). S. seychellanum: Raven, 1986: 67 , figs 46–49 (Ƥ). S. s.: Saaristo 2010: 23, figs 1.1-6 (Ƥ).

Material examined: SEYCHELLES: 13 (Zoological Museum, University of Turku, Finland), Silhouette Isl., Mon Plaisir, 550 m, 1.04.2010 (J. Gerlach).

Description. Male, total length 7.0. Carapace 4.25 long, 3.55 wide, fovea straight, transverse 0.57 wide; brown, with black eye area, dark brown cephalic part and dark-brown chevrons ( Fig. 3 ) and radial stripes; margins of carapace with strong spiniform bristles ( Fig. 1 ). Sternum 2.25 long, 1.7 wide, sigilla not evident. Eye sizes and interdistances: AME 0.3, ALE 0.27, PME 0.14, PLE 0.2, AME–AME 1.4, ALE–ALE 0.66, AME–ALE 0.16, PME–PME 0.51, PLE–ALE 0.2, ALE–PLE 0, AME–PME 0.07; anterior row– 1.07, posterior row – 1.1. Chelicera each with 7 large prolateral teeth and 5 fine retrolateral teeth. Maxilla 1.64 long, 0.64 wide, cuspules absent. Labium 0.29 long, 0.64 wide, distinct cuspules absent ( Fig. 4 ), but with row of strong setae. Abdomen blackish with 3 pairs of whitish spots dorsally. Legs long, tibia I with mating spur (megaspine), with 4 prolateral ventral spines (including megaspine) and 4 retrolateral ventral spines ( Figs 5–6 ). Scopula on tarsi I and II and terminal part of metatarsi I-II. All claws with two rows of teeth; number of teeth vary on different sides, from 4-4 on leg I, 2-2 and 3-3 on legs III–IV respectively.

Length of leg and palp joint and number of spatulate trichobothria on tarsus.

Femur Patella Tibia Metatarsus Tarsus Total Spatulate trichobothria

Palp 2.15 1.35 1.85 - 0.8 6.15 9

Leg I 4.35 2.5 3.35 3.0 1.5 14.7 6 or 9 Leg II 4.35 2.25 3.45 3.0 1.4 14.45 7 or 8 Leg III 3.75 1.8 3.0 3.0 1.3 12.85 5 or 6 Leg IV 5.0 2.25 4.25 3.75 1.6 16.85 5.0

Palp as in Figs 7–11 , femur thicker and longer than tibia, “cymbium” with two lobes ( Figs 8, 10 ) with spatulate hairs; bulbus globular; embolus straight.

Distribution. Mahé ( Simon 1898; Benoit 1978), Silhouette ( Hirst 1911) and Aride ( Saaristo 2010).

Comments. The male is larger than females (carapace 3.92 long in lectotype). Males have a paired row of teeth present on all claws, but females have only two unpaired teeth on tarsi I and II; clypeal edge in male with 9, but not with 5 macrosetae. Three pairs of sigilla are present in females, but none are evident in this male. The male differs from females by having no cuspules, as in most Sason species.

Unlike in other species, males have paired ventral spines on tibia, a prolateral row with 4 spines, including terminal megaspine (mating spur) and 4 equally-sized spines on the retrolateral side. Furthermore, males of S. sechellanum differ from all other Sason species in having teeth on both faces of all claws rather than only on one face. Other species of Sason , S. andamanicum Simon, 1888 , S. hirsutum Schwendinger, 2003 , S. robustum (O.P.-Cambridge, 1883) and S. sundaicum Schwendinger, 2003 have only a megaspine in prolateral row and 4 spines in retrolateral row (cf. Raven 1986; Schwendinger 2003).

Figures

FIGURES 1 – 6. Somatic characters. 1 & 2 — habitus, in alcohol and dry specimen; 3 — cephalic part, dorsal; 4 — prosoma, ventral; 5 — tibia I, prolateral; 6 — tibia I, ventral.

FIGURES 7 – 12. Palp and tarsi I and II. 7 — palp, retrolateral; 8 — palp, prolateral; 9 – 11 — terminal part of palp, retrolateral, retro-ventral and ventral, respectively.