Ischnothyreus obscurus Richard

Richard, Miguel, Graber, Werner & Kropf, Christian, 2016, The goblin spider genus Ischnothyreus (Araneae, Oonopidae) in Java and Sumatra, Zootaxa 4151 (1), pp. 1-99 : 79-87

Ischnothyreus obscurus Richard , sp. nov.

( Figs. 63–69 )

Type material. Holotype: male (PBI_OON00052393), SUMATRA : Jambi Province, Mt. Kerinci, footpath to summit, W of Kersik Tua , 1800–1980m (evergreen hill forest), February 16, 2000; leg. P. Schwendinger (sifting), Sum-00/12. Natural History Museum Geneve .

Additional material examined. 1 male, 3 females (PBI_OON 00012854), collected with holotype. 3 males, 6 females (PBI_OON00031854), SUMATRA: Mt.Singalang. Arai , 400–520m, sec. forest, l. litter, June 9–24, 1994, leg. Suh. Djojosudharmo, Coll. Deeleman, NNM Leiden . 1 female (PBI_OON00031854), SUMATRA: Mt.Singalang. Arai , 400–520m, sec. forest, l. litter, June 9–24, 1994, leg. Suh. Djojosudharmo, Coll. Deeleman, NNM Leiden.

Etymology. The species epithet is an adjective meaning “dark” in Latin and refers to the overall dark coloration of this species.

Diagnosis. Males of I. obscurus sp. nov. strongly resemble males of I. haymozi sp. nov. in the pedipalps, and also the cheliceral process (p, Figs. 65 C, D, 66E, F). Also I. namo Kranz-Baltensperger, 2012 has very similar palps but differs more in the cheliceral process. I. obscurus sp. nov. males can be distinguished from I. haymozi sp. nov. males by the darker overall body coloration, especially the carapace coloration ( Figs. 63 A–D). The tip of the bulb is slightly longer and more slender in I. obscurus sp. nov. ( Figs. 64 A–I, 66B–D). I. obscurus sp. nov. possesses radial furrows on the sternum between coxae I–II, II–III and III–IV ( Fig. 63 F), which are lacking in I. haymozi sp. nov..

Females of I. obscurus sp. nov. can be identified by their genitalia: The surface of the postepigastric scutum bears no external structures but just a simple funnel surrounded by a row of hairs (f, Figs. 68 C, D, F). The posterior spiracles are connected by a groove and the postepigastric scutum is flanked by two small lateral sclerites of I. obscurus sp. nov. (ls, Figs. 68 B, F).

Description. Male: (PBI_OON00052393). Total length 1.99; carapace length: 1.01; carapace width: 0.85; abdomen length; 0.96.

CEPHALOTHORAX: Carapace orange-brown, broadly oval in dorsal view, pars cephalica strongly elevated in lateral view, anteriorly narrowed to 0.49 times its maximum width or less, surface of elevated portion of pars cephalica strongly reticulate, sides strongly reticulate; lateral margin straight, smooth. Clypeus margin unmodified, straight in front view, sloping forward in lateral view, high, ALE separated from edge of carapace by their radius or more. Eyes six, well developed, ALE largest, ALE oval, PME squared, PLE oval; posterior eye row straight from above, procurved from front; ALE separated by less than their radius, ALE-PLE touching, PME touching throughout most of their length, PLE-PME touching. Sternum as long as wide, pale orange, uniform, with radial furrows between coxae I–II, II–III, III–IV, furrow smooth, surface smooth, microsculpture absent, lateral margin without infra-coxal grooves, distance between coxae approximately equal, extensions of pre-coxal triangles present, lateral margins unmodified; setae dark, needle-like, evenly scattered, originating from surface. Mouthparts: Chelicerae, endites and labium pale orange. Chelicerae straight, anterior face unmodified; directed medially, shape normal, tip unmodified; setae dark, needle-like, evenly scattered. Fang base with weakly sclerotized process with variable orientation (p, Figs. 65 C, D, 66E, F). Labium elongated hexagon, not fused to sternum, anterior margin not indented at middle, same as sternum in sclerotization; with setae. Endites distally not excavated, anteromedian tip with one strong, tooth-like projection, much more heavily sclerotized than sternum.

ABDOMEN: ovoid, pointed posteriorly; dorsum soft portions pale orange, without color pattern. Posterior spiracles connected by groove. Scutum extending far dorsal of pedicel. Dorsal scutum weakly sclerotized, orangebrown, without color pattern, covering 1/2 to 3/4 of abdomen, more than 1/2 to most of abdomen width, fused to epigastric scutum, middle surface smooth, sides smooth. Epigastric scutum weakly sclerotized, surrounding pedicel, not protruding, small lateral sclerites absent. Postepigastric scutum weakly sclerotized, pale orange, short, almost rectangular, covering about 1/3 of the abdominal length, fused to epigastric scutum, anterior margin unmodified. Dorsum setae present, dark, needle-like. Spinneret scutum without fringe of setae.

LEGS: pale orange, without color pattern; patella plus tibia I near as long as carapace, tibia I unmodified. Leg spination: femora: I p0-1-1; II p0-0-1; tibiae: I, II p2-2-0; r2-2-0; metatarsi: I, II p1-1-0; r1-1-0.

GENITALIA: Bulb with one large edged ventral protuberance, retrolateral lobe flat (rl, Figs. 64 H). Tip of bulb slightly elongated, slender, with prolateral groove and distal tongue-shaped membrane (pg, tsm, Figs. 64 F–H, 66B–D).

Female: (PBI_OON12854). Total length 2.74; carapace length: 1.20; carapace width: 0.98; abdomen length; 1.48.

CEPHALOTHORAX: Carapace yellow-brown, without any pattern, pars cephalica slightly elevated in lateral view, surface of elevated portion of pars cephalica finely reticulate. Eyes six, well developed, ALE largest, all eyes oval; posterior eye row procurved from both above and front; ALE separated by less than their radius, ALE-PLE touching, PME touching throughout most of their length, PLE-PME touching. Sternum extensions of pre-coxal triangles absent. Mouthparts: Chelicerae without prominent basal process. Labium rectangular, anterior margin indented at middle, endites anteromedian tip unmodified, posteromedian part unmodified. Female palp claws absent; spines present, formula: femur p0-0-1, r2-1-1; tarsus unmodified.

ABDOMEN: dorsum soft portions white. Scutum not extending far dorsal of pedicel. Dorsal scutum covering less than 1/2 of abdomen, between 1/4 and 1/2 abdomen width, not fused to epigastric scutum. Epigastric scutum slightly protruding, small lateral sclerites present. Postepigastric scutum only around epigastric furrow, with short posteriorly directed lateral apodemes. Spinneret scutum with fringe of needle-like setae.

LEGS: yellow-brown, patella plus tibia I longer than carapace. Leg spination: femora: I p0-1-1; II p0-0-1; tibiae: I, II p2-2-0; r2-2-0; metatarsi: I, II p1-1-0; r1-1-0.

GENITALIA: Apodemes lateral of winding tube with openings to surface of postepigastric scutum (wt, a, Figs. 68 C, F), postepigastric scutum with funnel and row of pores, (f, po, Figs. 68 C–F).

Distribution. Known from middle Sumatra.

Figures

FIGURE 63. Ischnothyreus obscurus sp. nov. Male: A, habitus, dorsal view; B, habitus, ventral view; C, carapace, frontal view; D, habitus, lateral view; E, opisthosoma, dorsal view; F, sternum, ventral view; G, opisthosoma, ventral view. Scale bar: A = 1 mm.

FIGURE 64. Ischnothyreus obscurus sp. nov. Male: A, I, right palp, prolateral view; B, right bulbus, retrolateral view; C, right bulbus, prolateral view; D, F, right embolus, retrolateral view; E, G, right embolus, prolateral view; H, right palp, retrolateral view. rl, retrolateral lobe; tsm, tongue-shaped membrane. Scale bars: A = 0.2 mm; B, H = 0.1 mm.

FIGURE 65. Ischnothyreus obscurus sp. nov. Male: A, C, right chelicera, posterior view; B, D, right chelicera, anterior view. p, process. Scale bars: A, C = 0.1 mm.

FIGURE 66. Ischnothyreus obscurus sp. nov. Male: A, leg I. SEM images: B, left palp, prolateral view; C, left embolus, posterior view; D, left embolus, prolateral view; E, left chelicera, posterior view; F, right chelicera, anterior view; G, sperm pore, ventral view; H, tarsal organ of leg III. p, process; pg, prolateral groove; rl, retrolateral lobe; tsm, tongue-shaped membrane. Scale bars: B, E = 0.1 mm; C, D, G = 20 µm; F = 50 µm; H = 5 µm.

FIGURE 67. Ischnothyreus obscurus sp. nov. Female: A, habitus, dorsal view; B, habitus, ventral view; C, carapace, frontal view; D, habitus, lateral view; E, opisthosoma, dorsal view; F, sternum, ventral view; G, opisthosoma, lateral view; H, opisthosoma, ventral view. Scale bar: A = 1 mm.

FIGURE 68. Ischnothyreus obscurus sp. nov. Female: A, leg I; B, D, F, genital area, ventral view; C, genital area, dorsal view; E, row of pores, ventral view. a, apodeme; f, funnel; ls, lateral sclerite; o, opening of apodeme; po, pores; ps, paddle-like sclerite; s, stigma; wt, winding tube. Scale bars: B, C, F = 0.15 mm; D = 0.1 mm; E = 20 µm.

FIGURE 69. Ischnothyreus obscurus sp. nov. Female, SEM images: A, genital area, ventral view; B, tip of tarsus IV; C, metatarsus-tarsus joint of leg IV, dorsal view; D, trichobothrium on tibia II; E, trichobothrium hood of tibia II; F, tarsal organ of left palp; G, tarsal organ of leg III; H, tarsal organ of leg IV. Scale bars: A = 0.15 mm; B, C, D = 20 µm; E, G = 5 µm; F = 10 µm; H = 2 µm.