Caerostris sumatrana Strand 1915

Jäger, Peter, 2007, Spiders from Laos with descriptions of new species (Arachnida: Araneae), Acta Arachnologica 56 (1), pp. 29-58 : 37-39

Caerostris sumatrana Strand 1915

Figs. 10-17

Material examined. 2 females, 3 juvenile females ( SMF 56333 ), L1, M. Grasshoff det. 2006 . 1 male ( SMF 56352 ), L3, 4.XI.2004, M. Grasshoff det. 2006 .

Additional material examined for comparison. 1 female ( SMF 3635 ), syntype of C. sumatrana Strand 1915 , Indonesien, Sumatra, Bandar Kwala , A. v. Auer leg. 1908 . 1 female ( SMF 4419 ), Indonesien, Java, Buitenzorg, Roewer det. 1935 sub C. mitralis (Vinson) , Grasshoff (1984) det. sub C. sumatrana .

Description. Male ( Figs. 10-12 , 16 ). Total length 4.0. Cymbium roughly circular; Conductor (“blattflache Apophyse” sensu Grasshoff 1984) large, pointed, membranous, at its base with a restricted field of dense granulation. Embolus with tip strongly sclerotised and separated from the basal part by a small crack (=?predetermined breaking point, see arrow in Fig. 11 ; unique among Caerostris males presently known); basal part of embolus with outer margin sclerotised and inner margin membranous. Prosoma without humps as present in females.

Female ( Figs. 13-15 , 17 ). Total length 15.2-17.6. Additionally to the descriptions given by Strand (1915) and Grasshoff (1984) slit sense organs were observed and illustrated ( Fig. 13 ), one close to the epigynal field, one included therein. The internal duct system consists of a first part with a circular coil, a mediad part leading to spherical receptacula and subsequently a posteriorad part followed by the fertilisation duct. The lamellar spines (“Lamellenborsten”) on femur IV are mainly wider than those illustrated by Grasshoff (1984: fig. 48).

Variation. Epigyna of specimens from Laos show differences to those from Indonesia: epigynal pits are slightly larger and rather circular (smaller and oval in Indonesian females). Opisthosomal humps are smaller in Laos material. Both is considered the result of intraspecific variation. Yin et al. (1997: figs. 130 b- c) show an epigynum without hooks (sub C. paradoxa ) and the internal duct system with only the most dorsal part (receptacula and fertilisations ducts) shown clearly.

Distribution. India, China, Laos, Indonesia (Sumatra, Java), Borneo(?).

Figures

Figs. 10 - 15. Caerostris sumatrana Strand 1915. Male (10 - 12) from Nam Ha (L 3), female (13 - 15) from Muang Sing (L 1). 10 Right male pedipalpus, ventral view, mirrored; 11 teguhim with embolus, ventral view (conductor removed; embolar crack indicated by arrow); 12 male prosoma, frontal view; 13 epigynum, ventral view; 14 internal duct system, dorsal view; 15 schematic course of internal duct system, dorsal view.

Figs. 16 - 17. Caerostris sumatrana Strand 1915. Male (16) from Nam Ha (L 3), female (17) from Muang Sing (L 1), feeding (in original habitat).