Ischnothyreus concavus 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: 42-50

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Ischnothyreus concavus Richard

sp. nov.

Ischnothyreus concavus Richard  , sp. nov.

( Figs. 31–37View FIGURE 31View FIGURE 32View FIGURE 33View FIGURE 34View FIGURE 35View FIGURE 36View FIGURE 37)

Type material. Holotype: male (PBI_OON 00052397), SUMATRA: Kerinci, N. Park, 800m, nr. river, leaflitter, July 21–30, 1988, leg. Suh. Djojosudharmo, Coll. Deeleman, NNM Leiden. 

Paratypes: 1 male, 5 females (PBI_OON00031883), collected with holotype.

Additional material examined. 1 male, 2 females (PBI_OON00031883), collected with holotype.

Etymology. The species epithet is an adjective meaning “concave” in Latin and refers to the concave shape of the male postepigastric scutum and to the male cheliceral paturon which has a concave retrolateral surface.

Diagnosis. Males of I. concavus  sp. nov. resemble males of I. tragicus Edward & Harvey 2014  in pedipalp and cheliceral morphology but can be distinguished from the former by the flattened shape of the bulbal tip ( Figs. 32View FIGURE 32 E, G, 33C –F), the hook-shaped retrolateral lobe ( Figs. 33View FIGURE 33 E, F) and also by the shape of the chelicerae with the characteristic process on the fang base and the retrolateral edge of the paturon which appears concave in frontal view (p, rc, Figs. 32View FIGURE 32 F, H, 34A –D). Another characteristic trait is the concave postepigastric scutum, as the posterior edge of the scutum is protruding ventrally (pes, Fig. 31View FIGURE 31 F).

Females of I. concavus  sp. nov. can be identified by their genital area with the distinctively shaped winding tube flanked by the two apodemes (wt, a, Figs. 36View FIGURE 36 A –D). The more sclerotized central part of the postepigastric scutum reminds of the shape of ski goggles if viewed under the light microscope and is very diagnostic (gsp, Figs. 36View FIGURE 36 C, D).

Description. Male: (PBI_OON00052397). Total length 1.63; carapace length: 0.83; carapace width: 0.63; abdomen length; 0.77.

CEPHALOTHORAX: Carapace pale orange, with two small dark spots visible on the egg shaped patches (ds, Fig. 32View FIGURE 32 C), 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 smooth, sides finely 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 circular, PME oval, PLE 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 touching throughout most of their length, PLE- PME touching. Sternum as long as wide, pale orange, uniform, surface smooth, microsculpture absent, lateral margin without infra-coxal grooves, distance between coxae approximately equal, extensions of pre-coxal triangles absent, lateral margins unmodified; setae abundant, 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 light, needle-like, evenly scattered; paturon distal region abruptly narrowed, paturon retrolaterally slightly concave, fang base with process (ca, rc, Figs. 32View FIGURE 32 F, H, 34A –D). Labium rectangular, not fused to sternum, anterior margin not indented at middle, same as sternum in sclerotization; with 1 or 2 setae on anterior margin, subdistal portion with unmodified 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 yellow, without color pattern. Posterior spiracles not connected by groove. Scutum extending far dorsal of pedicel. Dorsal scutum strongly sclerotized, pale orange, without color pattern, covering 1/2 to 3/4 of abdomen, between 1/4 and 1/2 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, yellow, short, almost rectangular, covering about 1/3 of the abdominal length, fused to epigastric scutum, anterior margin unmodified, Postepigastric scutum concave with posterior edge pointing ventrally in lateral view (pes, Fig. 31View FIGURE 31 F). Spinneret scutum present, incomplete ring. Dorsum setae present, light, needle-like. Epigastric area setae uniform, light, needle-like. Postepigastric area setae present, light, needle-like. Spinneret scutum with fringe of long 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 small ventral protuberance, retrolateral lobe hook-shaped (rl, Figs. 33View FIGURE 33 E, F). Tip of bulb slightly elongated, bent dorsally, with ventral pit.

Female: (PBI_OON00031883). Total length 1.77; carapace length: 0.82; carapace width: 0.67; abdomen length; 0.94.

As in male except as noted.

CEPHALOTHORAX: Carapace yellow-brown, without any pattern, pars cephalica slightly elevated in lateral view. Clypeus vertical in lateral view. Eyes all subequal, ALE oval, PME squared, PLE oval; PLE-PME separated by less than PME radius. Mouthparts: Chelicerae without prominent basal process; setae dark, needle-like, densest medially; paturon distal region unmodified. Labium anterior margin indented at middle. Endites distally not excavated, anteromedian tip unmodified, posteromedian part unmodified. Female palp claws absent; spines absent; tarsus unmodified.

ABDOMEN: dorsum soft portions yellow-brown. Scutum not extending far dorsal of pedicel. Dorsal scutum yellow-brown. Postepigastric scutum pale orange, widely hexagonal, only around epigastric furrow, not fused to epigastric scutum, with short posteriorly directed lateral apodemes. Dorsum setae present, dark, needle-like. Spinneret scutum with fringe of long setae. Dense patch of setae anterior to spinnerets present. Interscutal membrane with setae.

LEGS: Leg spination: femora: I p0-1-1; II p0-0-1; tibiae: I p2-2-0; r2-2-0; II p2-1-1; r2-2-0; metatarsi: I, II p1- 1-0; r1-1-0. GENITALIA: Winding tube thick, apodemes lateral of winding tube with openings to surface of postepigastric scutum, postepigastric scutum with central goggle-shaped process and row of pores (wt, a, gsp, Figs. 36View FIGURE 36 A –D).

Distribution. Known only from Kerinci National Park in middle Sumatra.


National Museum of Natural History, Naturalis