Trilacuna alces Eichenberger

Eichenberger, Beata & Kranz-Baltensperger, Yvonne, 2011, New Trilacuna species from Thailand, Malaysia and Sumatra (Araneae, Oonopidae), Zootaxa 2823, pp. 1-31 : 18

Trilacuna alces Eichenberger n. sp.

( Figs. 13–14 )

Type material: Holotype male ( PBI_OON 00012147 ): Thailand: Chiang Mai Province: Doi Pha Hom Pok, west of Fang , 20°02'42.9"N, 99°08'42.8"E, 2000 m, remnant patch of evergreen montane forest, 15. December 2002, leg. P. Schwendinger, deposited in MHNG. 1 female paratype ( PBI_OON 00032047 ), collected with holotype, leg. P. Schwendinger, deposited in MHNG.

Etymology: The species epithet, a noun in apposition, is the Latin word for moose and refers to the shape of the embolus-conductor-complex which, when observed under a stereomicroscope from the dorsal side, looks like the antlers of an moose.

Diagnosis: Similar to Trilacuna rastrum Tong & Li 2007 but both sides of carapace smooth with sparse granules only (fig. 13. E), endites distally only slightly branched, palp with a different set of membranes around embolus (figs. 14. E–H).

Description: Description based on 1 male and 1 female.

MALE: Body length 1.6 mm, proportion carapace length:abdominal length 1:1.13. Uniformly orange-brown species (figs. 13. A–C).

Carapace ovoid to broadly oval, slightly elevated, without spikes, lateral margin straight, rebordered, with blunt denticles (figs. 13. E, F). Eyes posterior row straight from above, procurved from front. Sternum (fig. 13. D) with radial furrows of small pits between coxae, with striated impressions along midaxis, other surface smooth, anterior margin unmodified, setae abundant, needle-like, densest in the middle. Mouthparts: Labium rectangular, fused to sternum, anterior margin deeply incised (lid), (figs. 13. H–I); endites slender, distally only slightly branched (sdb), (fig. 13. I).

Abdomen: Ovoid, dorsal scutum not fused to epigastric scutum, postepigastric scutum long, semicircular, apodemes absent, posterior spiracles not connected by groove.

Legs: Ventral apex of tibiae III and IV with some specialized hairs with fine, plumose, curved hair tip (see fig. 16. H); metatarsi III, IV and tarsus IV with harpoon-like hairs (see fig. 2. G). Femora without spines.

Male genitalia: Epigastric region (fig. 14. A) with a strongly sclerotized, dark brown dot with a small opening (sld) at level of posterior spiracles, framed by lateral, needle-like hairs directed to center (lns). Male palp (figs. 14. C–H) embolus-conductor complex complicated, divided into two conspicuous branches with a retrolateral embolic part and a prolateral conductor-complex. Embolus (emb) long, slender, lamellar, curved mesially, distally framed by a broadish, smooth appendage with lateral, thick setae (ba) (figs. 14. E–H). Conductor-complex with a basal ovoid piece (bop) with one side smooth, other side covered with thin setae; with 3 basal, tongue-like, ventrally directed, dark brown lobes (tdl) and a medial pair of ventral-distally directed, light lobes (mpl), adjacent to a pair of long, dark brown lobes (ldl) and a distal lobe with widened base and pointed tip (dl); all lobes framed by sparse, thin hairs, with extensive dorsal brush of hairs (ebh) (figs. 14. E–H). Bulb more than two times as long as cymbium, pear-shaped, tapering apically, prolaterally abruptly narrowed, with a blunt angle (bla) (figs. 14. C–D). Femur enlarged, stout (figs. 14. C–D).

FEMALE: Body length 1.8 mm, proportion carapace length:abdominal length 1:1.17. Carapace broadly oval in dorsal view. Posterior eye row recurved from above, all eyes about subequal, roundish. Endites distally not branched. Sternum setae sparse, evenly scattered. Postepigastric scutum not fused to epigastric scutum, posterior spiracles connected by dark brown groove (gr), (fig. 14. B); with two strongly sclerotized, recurved arches (sar), (fig. 14. B) anterior to the posterior spiracles; posterior border of epigastric scutum and anterior border of postepigastric scutum with dark brown seam.

Female genitalia: Ventral view (fig. 14. B): Epigastric furrow anteriorly bordered by procurved fold of uterus externus (fo) ending in two lateral dark-brown knobs (dk); with a short, longitudinal structure in the middle (ls).

Distribution: Known only from type locality, the Doi Pha Hom Pok (the second highest mountain of the country) in northern Thailand.

Figures

FIGURE 13: Trilacuna alces n. sp. Male: A. habitus dorsal view; B. habitus ventral view; C. habitus lateral view; D. sternum ventral view; E. carapace dorsal view; F. carapace lateral margin, dorsal view; G. carapace anterior view; H – I. mouthparts ventral view. Abbreviations: boc, booklung covers; ldi, labium deep incision; sdb, slight distal branch. Scale bars: A – C 1 mm; D – E, G 0.5 mm; F 100 Μm; H, I 200 Μm.

FIGURE 14: Trilacuna alces n. sp. Male: A. gonopore ventral view; C – D. left palp, prolateral view; E – F. left embolus, prolateral view; G – H. left embolus, dorsal view. Female: B. epigastric region, ventral view. Abbreviations: sld, sperm pore like dot; lns, lateral needle-like setae; fo, fold of uterus externus; dk, dark brown knob; short, longitudinal structure (ls); gr, groove connecting posterior spiracles; sar, sclerotized arch; emb, embolus; ba, broadish appendage framed by lateral setae; dl, distal lobe; tdl, three basal, tongue-like, dark lobes; mpl, medial pair of light lobes; ldl, long dark brown lobes; bop, basal ovoid piece; ebh, extensive dorsal brush of hairs; bla, blunt angle. Scale bars: A – D 300 Μm; E – H 50 Μm.