Ischnothyreus microphthalmus 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 : 71-79

Ischnothyreus microphthalmus Richard , sp. nov.

( Figs. 56–62 )

Type material. Holotype: male (PBI_OON00052402), SUMATRA: Mt.Singalang, Arai , 400–520m, sec. forest, l. litter, June 9–24, 1994, leg. Suh. Djojosudharmo, Coll. Deeleman, NNM Leiden.

Paratypes: 3 females (PBI_OON00031838), collected with holotype.

Additional material examined. 2 females (PBI_OON00031838), collected with holotype.

Etymology. The species epithet is an adjective meaning “small-eyed” in Latin and refers to the reduced size of the eyes of this species.

Diagnosis. Males and females of I. microphthalmus sp. nov. can be identified by the reduced size of their eyes ( Figs. 56 A, C, D, F, 60A, C, D, 62A) in combination with the striated coloration of leg IV ( Figs. 56 A, B, 57D, 61D).

Males have a strongly sclerotized but totally smooth carapace ( Fig. 56 F). Male pedipalps show a blunt tip of the bulb, provided with characteristic small dorsal spikes ( Figs. 58 E, F). The retrolateral lobe appears flat and roundish and the bulb has two flat ventral protuberances of which the retrolateral one is smaller (rl, Figs. 58 G, H). Males of I. microphthalmus sp. nov. also possess a characteristic process on the base of the cheliceral fang (p, Figs. 59 C, D).

Females resemble I. mulumi Kranz-Baltensperger, 2011 but the dorsal abdominal scutum ( Fig. 60 A) is much smaller and the carapace surface ( Figs. 60 D, 62A) is not reticulate as it is in I. mulumi . The surface of the postepigastric scutum of I. microphthalmus sp. nov. is wrinkled around the winding tube and shows a triangleshaped process at the centre (tsp, Figs. 61 E, F, 62B).

Description. Male: (PBI_OON00052402). Total length 1.65; carapace length: 0.83; carapace width: 0.60; abdomen length; 0.75.

CEPHALOTHORAX: Carapace yellow-brown, ovoid 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 smooth, sides smooth, carapace dark but totally smooth; lateral margin straight, smooth; non-marginal pars thoracica setae dark, needle-like. Clypeus margin unmodified, straight in front view, vertical in lateral view, high, ALE separated from edge of carapace by their radius or more. Eyes six, reduced and very small, PME almost touching each other., all subequal, all eyes oval; posterior eye row procurved from both above and front; ALE separated by less than their radius, ALE-PLE separated by less than ALE radius, PME separated by less than their radius, PLE-PME separated by less than PME radius. Sternum longer than wide, pale orange, uniform, 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; paturon inner margin with scattered setae. Fang base with process (p, Figs. 59 C, D). Labium rectangular, not fused to sternum, anterior margin not indented at middle, same as sternum in sclerotization; subdistal portion with unmodified setae. Endites distally not excavated, anteromedian tip with one strong, tooth like projection, much more heavily sclerotized than sternum.

ABDOMEN: cylindrical, pointed posteriorly; dorsum soft portions white, without color pattern. Posterior spiracles not connected by groove. Scutum extending far dorsal of pedicel. Dorsal scutum strongly sclerotized, yellow-brown, without color pattern, covering more than 3/4 of abdomen, more than 1/2 to most of abdomen width, not 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. Spinneret scutum present, incomplete ring. Dorsum setae present, dark, needle-like. Spinneret scutum with fringe of needle-like setae. Interscutal membrane with 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 p2-1-1; r2-1-1; metatarsi: I, II p1-1-0; r1-1-0.

GENITALIA: Bulb with two flat ventral protuberances, retrolateral protuberance smaller, retrolateral lobe large and flat (rl, Figs. 58 G, H). Tip of bulb slightly elongated, blunt, with dorsal spikes (sp, Figs. 58 E, F). Female: (PBI_OON00031838). Total length 1.92; carapace length: 0.78; carapace width: 0.64; abdomen length; 1.06.

CEPHALOTHORAX: Carapace without any pattern, broadly oval in dorsal view, pars cephalica slightly elevated in lateral view, anteriorly narrowed to between 0.5 and 0.75 times its maximum width, dark but very smooth lacking any surface sculpturation. Clypeus sloping forward in lateral view. Eyes six, reduced and very small. ALE largest, all eyes oval; posterior eye row straight from above, procurved from front; ALE separated by less than their radius, ALE-PLE separated by less than ALE radius, PME touching for less than half their length, PLE-PME separated by PME radius to PME diameter. Sternum as long as wide, pale orange, extensions of precoxal triangles absent. Mouthparts: Chelicerae slightly divergent; fangs directed posteriorly, shape normal. Endites anteromedian tip unmodified, posteromedian part unmodified. Female palp claws absent; spines absent; tarsus unmodified.

ABDOMEN: ovoid, rounded posteriorly; scutum not extending far dorsal of pedicel. Dorsal scutum weakly sclerotized, covering 1/2 to 3/4 of abdomen, between 1/4 and 1/2 abdomen width, dorsal scutum anteriorly narrowed, shape drop-like. Postepigastric scutum orange-brown, widely hexagonal, only around epigastric furrow, not fused to epigastric scutum, with short posteriorly directed lateral apodemes. Spinneret scutum present, incomplete ring. Spinneret scutum with fringe of stout setae. Interscutal membrane with setae.

LEGS: patella IV proximally darker than distally, tibia IV proximally darker than distally, metatarsus IV proximally darker than distally. Leg spination: femora: I p0-1-1; II p0-0-1; tibiae: I, II p2-1-1; r2-1-1; metatarsi: I, II p1-1-0; r1-1-0. Tarsi I to IV superior claws tooth not examined in detail.

GENITALIA:Winding tube large, apodemes lateral of winding tube with openings to surface of postepigastric scutum (wt, a, Figs. 61 E, F), postepigastric scutum with wrinkles, central triangle-shaped process and pore field, (tsp, pf, Figs. 61 E, F, 62B–D).

Distribution. Known only from Mt. Singalang in middle Sumatra.

Figures

FIGURE 56. Ischnothyreus microphthalmus sp. nov. Male: A, habitus, dorsal view; B, habitus, ventral view; C, carapace, frontal view; D, habitus, lateral view; E, sternum, ventral view; F, carapace, dorsal view. Scale bar: A = 1 mm.

FIGURE 57. Ischnothyreus microphthalmus sp. nov. Male: A, opisthosoma, dorsal view; B, opisthosoma, ventral view; C, opisthosoma, lateral view (mirrored image); D, leg VI; E, leg I; F, leg II; G, leg III.

FIGURE 58. Ischnothyreus microphthalmus sp. nov. Male: A, G, right palp, retrolateral view; B, H, right palp, prolateral view; C, E, right embolus, retrolateral view; D, F, right embolus, prolateral view. eo, embolic opening; rl, retrolateral lobe; sp, spikes. Scale bars: A, G = 0.1 mm.

FIGURE 59. Ischnothyreus microphthalmus 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 60. Ischnothyreus microphthalmus sp. nov. Female: A, habitus, dorsal view; B, habitus, ventral view; C habitus, lateral view; D, carapace, dorsal view; E, sternum, ventral view; F, opisthosoma, ventral view; G, postepigastric scutum, ventral view. Scale bar: A = 1 mm.

FIGURE 61. Ischnothyreus microphthalmus sp. nov. Female: A, leg I; B, leg II; C, leg III; D, leg VI; E, genital area, dorsal view; F, genital area, ventral view. a, apodeme; o, opening of apodeme; pf, pore field; s, stigma; tsp, triangle-shaped process; wt, winding tube. Scale bars: E, F = 0.1 mm.

FIGURE 62. Ischnothyreus microphthalmus sp. nov. Female, SEM images: A, carapace, dorsal view; B, genital area, ventral view; C, surface of postepigastric scutum, ventral view; D, pore field, ventral view; E, spinnerets, ventral view; F, tarsal organ of leg I. pf, pore field; tsp, triangle-shaped process. Scale bars: A = 0.2 mm; B = 0.1 mm; C = 20 µm; D, F = 5 µm; E = 50 µm.