Perania tumida, Schwendinger, 2013

Schwendinger, Peter J., 2013, A taxonomic revision of the spider genus Perania Thorell, 1890 (Araneae: Tetrablemmidae: Pacullinae) with the descriptions of eight new species, Revue suisse de Zoologie 120 (4), pp. 585-663 : 607-611

Perania tumida sp. n. Figs 7-8

HOLOTYPE: MHNG, sample TH-05/21; Ƌ (matured 27.X.2006; exuvia preserved); Thailand, Uttaradit Province, Nam Pat District, Phu Soi Dao (= Phu Soay Dao) National Park , rivulet below Lan Son (17°42’N, 100°57’E), 1600 m; 22.XII.2005; leg. P. J. Schwendinger.

PARATYPES: 3 ♀ (one moulted 10.III.2006 and matured 27.X.2006) with same data as for holotype .

ETYMOLOGY: Latin adjective “tumidus, -a, -um” (= swollen). The species epithet refers to the clypeal hump of females in this species.

DIAGNOSIS: Similar to P. nasicornis , distinguished by: Males with apically slightly narrower clypeal process and with strap-like horizontal plates posteriorly on opisthosoma; cymbium with shorter apex; palpal organ with proximally narrower/shal- lower embolus carrying two lobate and one digitiform projections on deep apex. Females with a small clypeal hump and with conical dorsolateral microplates in posterior half of opisthosoma; vulva with spermathecae more extensively connected to each other in the middle; anterior collar with widely angular distal margin.

DESCRIPTION OF MALE (holotype): Colour (in alcohol) of prosoma, chelicerae, palps, proximal articles of leg I and anal plate dark brown, other sclerites reddish brown; membranous parts of opisthosoma light grey-brown. Clypeus with long, distally widened and flattened median process projecting foreward and slightly upward, occupying almost 30% of carapace length (Fig. 7A-B). Fovea indistinct and narrow. Total length 11.8. Carapace 6.7 long, 2.9 wide. Eye sizes and interdistances: PME 0.32 long, separated by 0.13; ALE 0.26 long; ALE-PLE 0.07; PLE 0.31 long, separated by 1.21. Labium 0.9 long, 1.2 wide. Sternum 2.8 long, 2.1 wide. Chelicerae without modifications; with one distinct and one indistinct tooth on anterior margin of fang furrow.

Palp 4.0 long (1.3+0.6+1.2+0.9). Cymbium (Fig. 7I) of typical shape, apex slightly shorter than in species previously described from Thailand. Bulbus globular; embolus large, distal half distinctly deeper than proximal half, apex split: lobate subterminal lamella with straight distal margin, overlapping deep embolic part with a narrowly rounded, lobate dorsal projection, a widely rounded lobate median projection and a small digitiform ventral projection (Fig. 7G-H).

Legs 3421. About 20 dark conical setal bases proventrally and ventrally on metatarsus I, about 10 shorter ones proventrally and ventrally in distal half of tibia I. Paired leg claws with a row of 14-16 teeth on anterior legs, 10-11 on posterior legs; unpaired leg claws with one denticle. Leg I 18.5 long (5.5+1.9+5.5+4.0+1.6), leg II 15.1 long (4.4+1.6+4.3+3.4+1.4), leg III 11.4 long (3.5+1.2+2.7+2.8+1.2), leg IV 14.6 long (4.3+1.3+3.8+3.9+1.3). Right leg I malformed (probably regenerated): with tibia, metatarsus and tarsus shorter and thicker than on left side, without conical setal bases.

Opisthosoma 5.1 long, 3.3 wide. Dorsal scutum 4.8 long, 3.3 wide, somewhat oval, its surface with indistinct elevations. Posterior side of opisthosoma with one strap-like horizontal plate just behind dorsal scutum. Pulmonary plate 3.4 long, 2.8 wide; genital region flat. Anterior pair of ventrolateral plates in males largely free, only their posterior tips fused with pulmonary plate. Postgenital plate completely fused to posterior margin of pulmonary plate, with a sclerotised suture linking them. Preanal plate 0.3 long, 0.9 wide, quadrangular, its anterior margin widely arched, its posterior and lateral margins straight. Anal plate 1.0 long, 1.5 wide.

DESCRIPTION OF FEMALE (“ allotype ”; not dissected): As in male, except for the following. Colour generally darker. Total length 11.3. Carapace 5.5 long, 3.1 wide; “cephalic” portion domed, with a short and basally wide conical hump on clypeus (Fig. 7C-D). PME 0.21 long, 0.24 apart; ALE 0.28 long; ALE-PLE 0.09; PLE 0.30 long, 1.54 apart. Labium 0.9 long, 1.3 wide. Sternum 3.2 long, 2.2 wide. Palp 4.6 long (1.3+0.6+1.1+1.6). Legs 3421; no conical setal bases on tibia I and metatarsus I, but with slightly enlarged setal bases ventrally on metatarsus I. Paired leg claws with a row of 12-15 teeth. Leg I 18.3 long (5.5+1.9+5.3+3.9+1.7), leg II 15.5 long (4.5+1.7+4.3+3.5+1.5), leg III 12.3 long (3.8+1.4+2.9+3.0+1.2), leg IV 15.3 long (4.6+1.5+4.0+3.9+1.3).

FIG. 7

Perania tumida sp. n. (A) Carapace of male holotype, dorsal view. (B) Same, lateral view. (C) Anterior portion of carapace of female “ allotype ”, dorsal view. (D) Same, lateral view. (E, F) Anterior portion of carapace of two female paratypes, dorsal view. (G) Left palp of holotype, proventral view. (H) Same, retrodorsal view. (I) Left cymbium of holotype, prolateral view. Abbreviation: dp = dorsal projection on embolic part of apex of palpal organ. Scale lines 1.0 mm (A-B; C-F; G-I).

FIG. 8

Perania tumida sp. n., two female paratypes. (A, D) Vulva, dorsal view. (B, E) Same, ventral view. (C, F) Same, anterior view. Scale lines 0.5 mm (A-B, D-E; C, F).

Opisthosoma 7.2 long, 4.0 wide; microplates in posterior half (especially dorsally) larger than others, conical and distinctly elevated. Dorsal scutum 5.4 long, 3.0 wide, narrower and with higher surface elevations than in male, especially along midline and in posterior portion. Pulmonary plate 3.1 long, 3.2 wide; genital region slightly more elevated than in male. Three slightly enlarged and laterally fused microplates anterior to anal plate; the latter 1.3 long, 1.5 wide.

Vulva (of paratypes) with fairly long anterior collar with angular anterior margin. Spermathecae and ventral wall of genital atrium uniformly pigmented. Spermathecae wide, slightly bulged; common anterior margin with a distinct median invagination; posterior margin more or less straight; lateral margins arched, posterolateral corners angular; narrow marginal poreplates lying in shallow trenches in anterior and lateral sides of spermathecae; ventral surface of spermathecae with oblique wrinkles in posterior portion (Fig. 8).

REMARK ON JUVENILES: The last exuvia of the male holotype has a clypeal hump very similar (only slightly wider) to that of the female “ allotype ”.

VARIATION: Carapace length in the three females examined ranges 4.9-5.5, carapace width 2.9-3.1. The clypeal hump of females is more pronounced in larger specimens than in smaller ones (Fig. 7C-F). One of the two vulvae examined has a shorter anterior collar than the other, otherwise both vulvae are very similar (Fig. 8). In the two female paratypes the slightly enlarged microplates that represent remnants of the preanal plate are not laterally fused as in the “ allotype ”.

RELATIONSHIPS: Strong similarities in male and female copulatory organs indicate closest relationship between P. tumida sp. n. and P. nasicornis .

DISTRIBUTION: Known only from the type locality, a mountain over 2100 m high, at the border between Thailand and Laos (Fig. 1, locality 14) . As the types were actually collected only a few hundred metres from a boundary marker, it is safe to assume that this species also occurs on the eastern slopes of the same mountain which lie in Xaignabouri Province , Laos .

BIOLOGY: The types were collected from the banks of a small seasonal stream in an evergreen gallery forest below a savannah with pine trees. The spiders lived in irregular loose sheetwebs running into a retreat in holes. No males were found in late December. The male holotype matured in captivity at the beginning of April, one of the female paratypes in late October of the following year.