Perania armata ( Thorell, 1890 )

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 : 636-640

Perania armata ( Thorell, 1890) Figs 24-26

Phaedima armata Thorell, 1890: 313 (description based on two female syntypes, these later lost). – Bourne, 1980: 250, 259 (mention as a “lost species” that belongs in Perania ).

Paculla armata ( Thorell, 1890) . – Simon, 1894: 573 (transfer).

Mirania armata ( Thorell, 1890) . – Lehtinen, 1981: 17, figs 3-5, 12 [description of male; designation of male neotype (in MZT, not examined); transfer].

Perania armata ( Thorell, 1890) . – Schwendinger, 1989: 579 (transfer by synonymisation of Mirania with Perania ).

TYPES: MCSNG; 2 ♀ syntypes (lost during flooding in 1970); Indonesia, Sumatra, West Sumatra Province, Singalang (= Gunung Singgalang, near Bukittinggi; about 0°23’S, 100°21’E) and Lubu Selassi (= Lubuk Selasih, on road from Padang to Solok, at the foot of Gunung Talang; about 0°57’50”S, 100°36’30”E); 1878; leg. O. Beccari. – Zoological Museum, University of Turku, Finland; Ƌ neotype (not examined); West Sumatra Province , 4 km SW of Padangpanjang, Lembah Anai (about 0°28’30”S, 100°21’10”E) at the foot of Gunung Singgalang ; 26.IX.1978; leg. P . T. Lehtinen.

NEW MATERIAL EXAMINED: MHNG, sample Sum-06/01; 1 Ƌ, 2 ♀, 4 juveniles (= 1 penultimate Ƌ, 1 penultimate ♀, 1 earlier instar, 1 very small juvenile); Indonesia, Sumatra, West Sumatra Province, forest above Taman Hutan Raya Bung Hatta, near road from Padang to Lubuk Selasih (0°56’45”S, 100°32’37”E), 1100 m; 29 ./ 30.V.2006; leg. P. J. Schwendinger.

DIAGNOSIS: Juveniles and adults of both sexes easily recognizable by a pair of distinct horns on “thoracic” portion of carapace; adults distinguished by details of their copulatory organs, females additionally by large opisthosomal plate separated from pulmonary plate.

RE-DESCRIPTION: The smallest nominal species in the genus (body 4.3-5.2 long), characterised by a pair of long, straight, dorsad-directed horns on “thoracic” portion of carapace in males, females and at least two juvenile instars (Fig. 24A-F). Cowpat-shaped tubercles in this region very low and indistinct. Clypeus without modification. Anterior margin of cheliceral furrow with two teeth. Few conical setal bases on tibia I and metatarsus I. Large, clearly outlined, somewhat pentagonal anterior opisthosomal plate separated from pulmonary plate in females (Fig. 24H-I). All microplates on posterior side of opisthosoma of new male isolated; all microplates on opisthosoma of females flat. Anterior pair of ventrolateral plates of males fused with pulmonary plate posteriorly and in median portion, leaving a narrow membranous stripe below the spiracles (see Lehtinen, 1981: fig. 4). Postgenital plate of male distinct or indistinct, more or less widely linked to pulmonary plate by a sclerotised suture. Preanal plate completely fragmented in females. Cymbium with moderately long, pointed apex (Fig. 25A, C; Lehtinen, 1981: fig. 5a). Palpal organ with ovoid bulbus and sigmoid embolus, the transition between the two U-shaped (Fig. 25A; Lehtinen, 1981: fig. 5a); embolus becoming gradually deeper in median portion, its apex shallower, indistinctly divided into a short, narrowly lobate subterminal lamella and a rounded embolic part without a tooth (Fig. 25B, D; Lehtinen, 1981: fig. 5b). Vulva wide, its anterior collar short and relatively narrow, not or only slightly surpassing FIG. 24

Perania armata ; male (A-C), two females (D, G-I), two juveniles (E-F). (A) Carapace, dorsal view. (B) Same, lateral view. (C) Carapace and chelicerae, anterior view. (D-F) Carapace, anterior view. (G) Left chelicera, anterior view. (H-I) Entire anterior opisthosomal plate separated from pulmonary plate, anterior view. Scale lines 1.0 mm (A-G; H-I).

FIG. 25

Perania armata ; male palp. (A) Distal portion of left palp, retrodorsal view. (B) Palpal organ, distal view. (C) Distal portion of left palp, proventral view. (D) Apex of right embolus, distal view. Scale line 1.0 mm.

common anterior margin of spermathecae (Fig. 26A, D); spermathecae with a more or less pronounced invagination in common anterior margin, lateral sides plane, without trenches (Fig. 26C, F), porepatches extending quite far onto dorsal side of spermathecae (Fig. 26A, D), ventral wall of spermathecae with a pair of wide, thick-walled internal chambers, these not connected by a median bridge (Fig. 26B, E); genital atrium quite short, with median zone of ventral wall weakly pigmented and less distinctly outlined than in P. nigra , lateral zones unpigmented (Fig. 26A-B, D-E).

VARIATION AND MEASUREMENTS: Carapace lengths in two males, including the neotype (and in two females) are 2.25-2.57 (2.49-2.51), carapace width 1.52-1.72 (1.66). The vulvae of two females are shown in Fig. 26. The neotype appears to have the spiracular plate incompletely fused with the pulmonary plate ( Lehtinen, 1981: figs 4, 12), which is not the case in the new male or in any other Perania male examined. The new male has a somewhat elliptical postgenital plate (about half as wide as the preanal plate) which is anteriorly widely connected to the posterior margin of the pulmonary plate, with a sclerotised suture linking both plates; in the neotype the postgenital plate appears to be more strongly reduced and completely fused with the pulmonary plate, possessing an almost straight posterior margin ( Lehtinen, 1981: 17, fig. 12). The preanal plate in the neotype ( Lehtinen, 1981: fig. 12) appears to be reduced in size, whereas in the new male it is distinctly larger and quite normal for Perania males. The new male carries two conical setal bases prolaterally in the distal quarter of its tibia I, and 5-6 such tubercles prolaterally and proventrally in the distal three-quarters of its metatarsus I; the male neotype has seven conical setal bases on metatarsus I, but none are mentioned for its tibia I ( Lehtinen, 1981: 17).

RELATIONSHIPS: Paired modifications in the “thoracic” portion of the carapace in both sexes and strong similarities in male and female copulatory organs strongly indicate that P. armata is most closely related to P. nigra . Similarities in the palpal organ also show a close relationship of these two species with P. korinchica . The

FIG. 26

Perania armata , two females (A-C; D-F). (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).

strongly developed pair of thoracic horns of P. armata is unique in the genus, but not without parallels in other genera. Less distinctly developed, paired thoracic protuberances (low mounds) are present in both sexes of P. nigra . These modifications in both species are probably homologous and synapomorphic, but are here not considered of generic significance.

DISTRIBUTION AND HABITAT: Known from four localities in the mountains near Padang in western Sumatra (Fig. 1, localities 27, 29-31). The new specimens were collected by sifting leaf litter in a disturbed upland rain forest. No webs were seen, but it is likely that P. armata lives in irregular sheetwebs which, according to the size of these spiders, are smaller than in congeners.

REMARKS: The two female syntypes described by Thorell were lost during the 1970 flooding of the MCSNG ( Bourne, 1980: 250; Lehtinen, 1981; 17) and still cannot be traced (M. Tavano, personal communication).

I cannot confirm that P. armata has “Abdominal plates slightly reduced when compared with Paculla, Lamania and Sabahya, but postgenital and preanal plates easily recognizable” ( Lehtinen, 1981: 16) and that its pattern of opisthosomal scuta is “intermediate between the normal pattern in Pacullini, and the strongly reduced pattern in Perania ” ( Lehtinen, 1981: 17). In the P. armata specimens examined the opisthosomal pattern of sclerites lies within the variation of the genus, is typical for the species on Sumatra, and (with regards to the anterior opisthosomal plate of females and the postgenital plate of males) is even more derived than that of P. nigra . What Lehtinen refers to as the isolated postgenital plate of the male neotype are obviously the median ventrolateral plates which are connected by a narrow bridge (see Lehtinen, 1981: fig. 12).

It is true that the posterior sternal process of P. armata is weakly developed ( Lehtinen, 1981: 76). It is smaller than in other Perania species, but only indistinctly smaller than the one of P. nigra . Nevertheless the sternal process of P. armata is posteriorly wide (wider than at the base) and truncate (see Lehtinen, 1981: fig. 12), as in all other Perania species (see Schwendinger, 1989: figs 7, 13), whereas in Sabahya, Paculla and Lamania it is conical or domed (see Lehtinen, 1981: fig. 24; Schwendinger, 1989: fig. 2). With respect to this character P. armata lies at the lower end of the variation within Perania , but not outside it.

Lehtinen (1981: 17) regarded the male palp of P. armata as “close to that of P. picea ”, but I see much stronger similarities with the palp of P. nigra (Fig. 25 cf. Fig. 22).