Perania ferox, 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 : 603-607

publication ID 10.5281/zenodo.6119025

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Perania ferox

sp. nov.

Perania ferox View in CoL sp. n. Figs 4-6

HOLOTYPE: MHNG; Ƌ; Thailand, Tak Province, km 121 on road from Mae Sot (= Mae Sod) to Umphang (about 16°14’N, 98°59’E), 1270 m; 8.X.1993; leg. P. J. Schwendinger. GoogleMaps

PARATYPES: 2 Ƌ (one matured in late January 1994) and 4 ♀ (one selected as “ allotype ”) with same data as for holotype GoogleMaps .

ETYMOLOGY: Latin adjective “ferox” = fierce; referring to the aggressive defence behaviour of this species.

DIAGNOSIS: Females most similar to the female holotype of P. birmanica , distinguished by slightly bulged spermathecae indistinctly separated from each other by oblique bands without pigmentation; anterolateral sides of spermathecae convex, poreplates not lying in trenches; posterior margin of anterior collar fairly straight, without median indentation. Males with long clypeal process; palpal organ similar to that of P. nasicornis , but embolic part of apex shallower, without dorsal projection, not overlapping subterminal lamella.

DESCRIPTION OF MALE (holotype): Colour (in alcohol) of sclerotised parts mostly dark reddish brown; leg I slightly darker than other legs; membranous parts of opisthosoma light grey-orange. Clypeus with long, distally widened and flattened median process projecting foreward and slightly upward, occupying about 20% of carapace length (Fig. 4A-B). Fovea indistinct and narrow. Total length 10.2. Carapace 5.6 long, 2.7 wide. Eye sizes and interdistances: PME 0. 26 long, separated by 0.19; ALE 0.27 long; ALE-PLE 0.07; PLE 0.27 long, separated by 1.26. Labium 0.7 long, 1.1 wide. Sternum 2.9 long, 2.0 wide. Chelicerae without hump at distolateral corner, with two distinct teeth on anterior margin of fang furrow.

Palp 3.6 long (1.2+0.6+1.1+0.7). Cymbium of typical shape (Fig. 5C). Bulbus globular; embolus large, only slightly bent in its distal portion, apex deeply split: subterminal lamella quite deep, rounded and tongue-shaped, separated by an acute invagination from the much shallower and pointed embolic part (Fig. 5A-B).

FIG. 4

Perania ferox sp. n. (A) Carapace of male holotype, dorsal view. (B) Same, lateral view. (C, D) Anterior portion of carapace of two male paratypes, dorsal view. (E) Same of penultimate male (exuvia). (F) Anterior portion of carapace of female “ allotype ”, dorsal view. (G) Same, lateral view. (H) Dorsal opisthosomal scutum of “ allotype ”, dorsal view. Scale lines 1.0 mm (A-B; C-D; E-G; H).

Legs 3421. About 12 strong dark conical setal bases prolaterally to ventrally on metatarsus I, about 10 smaller ones prolaterally spread over most of tibia I. Paired leg claws with a row of 9-13 teeth (decreasing in numbers from anterior to posterior legs); unpaired leg claws with one denticle. Leg I 15.5 long (4.7+1.8+4.5+3.1+1.4), leg II 12.5 long (3.7+1.4+3.4+2.7+1.3), leg III 9.6 long (2.9+1.1+2.2+2.3+1.1), leg IV 12.3 long (3.6+1.2+3.2+3.1+1.2).

Opisthosoma 4.6 long, 3.0 wide. Dorsal scutum 4.4 long, 2.9 wide, somewhat oval, its surface with only very indistinct elevations. All lateral microscerites flat, those in upper three bands on posterior margin of opisthosoma still fused into strap-like horizontal plates. Pulmonary plate 3.2 long, 2.5 wide; genital region flat. Anterior pair of ventrolateral plates completely free, their posterior tips only touching margin of pulmonary plate. Postgenital plate completely fused to posterior margin of pulmonary plate, with a sclerotised suture linking them. Preanal plate 0.3 long, 1.0 wide, FIG. 5

Perania ferox sp. n. (A) Left palp of holotype, proventral view. (B) Same, retrodorsal view. (C) Left cymbium of holotype, prolateral view. (D, F) Apex of embolus of two male paratypes, prolateral view. (E, G) Same, retrodorsal view. Scale line 1.0 mm.

quadrangular, all margins uneven, the posterior one more distinctly arched than the others. Analplate 0.9 long, 1.3 wide.

DESCRIPTION OF FEMALE (“ allotype ”; not dissected): As in male, except for the following. Totallength 8.7. Carapace 4.3 long, 2.7 wide; “cephalic” portiondomed, anterior margin straight, without clypeal process (Fig. 4F-G). PME 0.25 long, 0.20 apart; ALE 0.22 long; ALE-PLE 0.10; PLE 0.24 long, 1.39 apart. Labium 0.8 long, 1.1 wide. Sternum 2.7 long, 2.0 wide. Right chelicera with two strong teeth on anterior margin of fang forrow, left chelicera with one strong and one weak tooth. Palp 3.6 long (1.1+0.5+0.8+1.2). Legs 3241; tibiaIandmetatarsusIwithoutconicalsetalbases. Paired leg claws with a row of 11-12 teeth on anterior legs, 8-10 on posterior legs. Leg I 12.8 long (3.8+1.5+3.5+2.7+1.3), legII 10.8 long (3.1+1.3+2.8+2.4+1.2), legIII 8.7 long (2.6+1.1+2.0+2.0+1.0), legIV 11.2 long (3.3+1.2+2.8+2.8+1.1).

Opisthosoma 5.3 long, 3.5 wide; several microplates posterolaterally very distinctly elevated and conical, those on posterior side of opisthosoma flat, very close to each other, but not fused into horizontal strap-like plates. Anterior plate fragmented into microplates of different sizes. Dorsal scutum 3.5 long, 2.4 wide, subquadrangular (in contrast to ovoid dorsal scutum of P. birmanica holotype, Fig. 4H cf. Fig. 3C). Pulmonary plate 2.6 long, 2.5 wide; genital region almost flat, its posterior margin slightly convex. Four laterally extended microplates in front of anal plate, the latter 9.1 long, 1.3 wide.

Vulva (of paratypes) with short anterior collar with moderately arched (or widely angular) anterior margin and straight posterior margin; collar not or only slightly surpassing anterior margin of spermathecae. Ventral side of vulva almost completely pigmented. Spermathecae short, wide and slightly bulged, indistinctly separated from each other by a more or less pronounced, quite shallow median invagination in common anterior margin and by oblique unpigmented bands medially on ventral surface; porepatches narrow and marginal, on convex surface, not lying in trenches (Fig. 6).

REMARK ON JUVENILES: In mature specimens the carapace is firmly connected to the sternum by lateral bridge-sclerites between the leg coxae. In juveniles these connections are not yet in place. The last exuvia of a male paratype has split open along the carapace margin as usual in spiders.

VARIATION: Carapace length in three males (four females) ranges 5.3-6.1 (4.2-4.6), carapace width 2.6-3.0 (2.7-2.9). In the holotype and one male paratype the posterior tips of the anterior pair of ventrolateral plates are only touching the margin of the pulmonary plate, in a second male paratype they are fused with it. One male paratype has all strap-like horizontal plates on the posterior side of the opisthosoma broken. For variation in the shape of the palpal organ of three males (mostly expressed in the angle between the dorsal subterminal lamella and the ventral embolic part) see Fig. 5A-G; for variation in copulatory organs of two females see Fig. 6. The postgenital plate is completely fused to the pulmonary plate in two males (including the holotype) and medially separated by a small membranous stripe behind the gonopore in one male. The females examined have 3-4 laterally extended microplates (fragments of the preanal plate) in front of their anal plate.

RELATIONSHIPS: Judging from strong similarities in copulatory organs of females, P. ferox sp. n. is most closely related to P. birmanica and P. quadrifurcata sp. n. The embolus of P. ferox sp. n. is less complex than that of P. quadrifurcata sp. n. but of similar overall shape. The geographical proximity of these two species and P. birmanica on both sides of the border between Thailand and Myanmar (see Fig. 1, localities 12, 13, 16-19) also suggests a close relationship.

DISTRIBUTION: Known only from the type locality in western central Thailand, close to the border with Myanmar’s Kayin (= Karen) State (Fig. 1, locality 13) .

BIOLOGY: The spiders examined were collected from steep banks of a small stream in an evergreen hill forest at 1270 m. They lived in loose-meshed sheetwebs running into a retreat as typical for Perania . One female used the abandoned burrow of a Liphistius female (with an intact exuvia at the bottom) as its retreat. Two P. ferox sp. n. females had newly shed exuviae in their webs when collected in early October. One juvenile male matured at the end of January. It continued to feed for about three

FIG. 6

Perania ferox 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).

months, but then refused prey and died four months into maturity. When collected, the spiders reacted unusually aggressively for Perania : threatening by raising their anterior legs (as theraphosid spiders do) and biting the forceps.


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