Trilacuna diabolica Kranz-Baltensperger

Eichenberger, Beata & Kranz-Baltensperger, Yvonne, 2011, New Trilacuna species from Thailand, Malaysia and Sumatra (Araneae, Oonopidae), Zootaxa 2823, pp. 1-31 : 26-30

Trilacuna diabolica Kranz-Baltensperger n. sp.

( Figs. 19–20 )

Type material: Male holotype ( PBI_OON 00012605 ), Thailand: Kanchanaburi Province: Bo Phloi District: near Tham (= cave) Than Lod Noi , 300 m, 12 November 1992, leg. P. Schwendinger, deposited in MHNG . Female paratype ( PBI_OON 00012605 ), collected with holotype, deposited in MHNG .

Etymology: The specific name is derived from the Latin adjective “diabolicus, -a, -um” and refers to the devilish look of the specimens.

Diagnosis: This species can be distinguished from all other Trilacuna species by its smooth carapace surface with few granulate spots in the cephalic region (fig. 19. G) and conspicuous spikes in different sizes and shapes, each bearing a rather long hair, covering the surface and margin of the carapace (figs. 19. A, C–D) and the labium which is not deeply incised but indented (fig. 19. E).

Description: Description based on 1 male and 1 female.

MALE (holotype): Prosoma length 1.06 mm, width 0.83 mm. Opisthosoma length 1.11 mm, width 0.97 mm. Prosoma dark red-brown, chelicerae, endites and labium, legs, and opisthosoma orange-brown, sclerite surrounding spinnerets light orange; spinnerets pale yellow; soft areas white (figs. 19. A–C).

Carapace: ovoid, pars cephalica strongly elevated (fig. 19. C), narrowed in eye region; pars cephalica with long, needle-like setae, spikes on carapace also bearing long, needle-like setae. Eyes set back from anterior margin of clypeus by more than their radius, ALE largest and circular, PME and PLE oval, posterior eye row recurved from above, straight from front (figs. 19. A, D, G). Sternum longer than wide, fused to carapace, with radial furrows between coxae I–II, II–III, III–IV, furrow with rows of small pits (fig. 19. E). Sternum surface coarsely reticulate (figs. 19. E, H), sternum covered with many needle-like setae (figs. 19. B, E, H). Mouthparts: Labium trapezoid, longer than wide, not fused to sternum, anterior margin indented at middle; with 3–5 setae on anterior margin. Endites unmodified. Chelicerae slightly divergent, shape normal, anterior basal region slightly protruding, setae needle-like, evenly scattered. Fangs directed slightly posteriorly.

Abdomen: ovoid; large scutum covering entire dorsal surface, not fused to epigastric scutum; large ovoid booklung covers without setae; pedicel tube ribbed (figs. 19. B, F; 20. E); epigastric scutum covering ¾ of abdomen, slightly protruding, posterior spiracles connected by groove, many very long setae reaching from pedicel until groove between posterior spiracles. Spinneret scutum present as incomplete ring with a fringe of needle-like setae; colulus represented only by setae.

Legs: long, with spines as follows: leg I: femur: one spine prolaterally; tibia: four spines prolaterally, three spines retrolaterally; metatarsus with two spines prolaterally and two spines retrolaterally; leg II alike, but femur without spines; leg III and leg IV without spines.

Male genitalia: palp pale orange, tibia with three trichobothria, two on dorsal part of prolateral side, one retrolaterally, cymbium pale orange, narrow, with tiny hairs, not fused with bulb, not extending beyond distal tip of bulb, which is 1 to 1.5 times as long as the cymbium. Bulb thick, tapering apically, bearing small denticles at its end, tip brush-like, embolus short, slender, covered by “brush” (figs. 20. A–D). Epigastric scutum with conspicuous knob, a region with long setae extending from this knob to the epigastric furrow.

FEMALE (paratype): As in male except as noted. Larger than male with somewhat longer spikes on the carapace. Pars cephalica slightly elevated. Prosoma length 1.11 mm, width 0.88 mm. Opisthosoma length 1.56 mm, width 1.22 mm. Ventral scutum divided by epigastric furrow in an anterior epigastric scutum surrounding pedicel and a posterior epigastric scutum covering almost whole underside of opisthosoma. Parts of vulva shining through the integument (figs. 19. F; 20. E).

Female genitalia: simple in ventral view (figs. 19. F; 20. E). Posterior spiracles connected by sclerotized arch (figs. 19. F; 20. E).

Ecology: The known specimens were found near a natural tunnel through a limestone hill.

Distribution: Known only from the type locality in western central Thailand.

Figures

FIGURE 19: Trilacuna diabolica n. sp. Male: A. habitus dorsal view; B. habitus ventral view; C. habitus lateral view; D. carapace dorsal view; E. carapace ventral view. Female: F. abdomen ventral view; G. carapace dorsal view. H. carapace ventral view. Scale bars: 0.5 mm. Arrowhead points to the row of small pits in fig. 19. E and to the spikes bearing a rather long hair in fig. 19. G.

FIGURE 20: Trilacuna diabolica n. sp. Male: A. left palp, retrolateral view; B. left palp, prolateral view; C. tip of left palp, retrolateral view; D. tip of left palp, prolateral view. Female: E. abdomen, ventral view. Scale bars: A – B 100 Μm; C, E 10 Μm; D 50 Μm.