Hersilia serrata, Dankittipakul & Singtripop, 2011

Dankittipakul, Pakawin & Singtripop, Tippawan, 2011, The spider genus Hersilia in Thailand, with descriptions of two new species (Araneae, Hersiliidae), Revue suisse de Zoologie 118 (2), pp. 207-221 : 213-216

Hersilia serrata sp. n. Figs 15-19, 30

HOLOTYPE: MHNG-PDC-244545122222-109; Thailand, Chiang Mai Province and District, Chiang Mai University campus, Ang Kaew , 300-350 m; 1 male; 4.10.2007; on a tree trunk in an open area; leg. P. Dankittipakul.

PARATYPES: MHNG-PDC-875415454545987321; from the type locality; 1 female; 10.11.2007; leg. P. Dankittipakul. – MHNG-PDC-457857181554543222-256; Thailand, Chiang Mai Province, Chomthong District, Doi Inthanon NP, Doi Inthanon , on a tree trunk in degraded natural forest interspersed with pine trees behind a guest house, 1200-1300 m; 1 female; 1.- 4.7.2002; leg. P. Dankittipakul. – MHNG-PDC-515432321544142114789; Thailand, Phitsanulok Province, Nakhon Thai District, Thung Salaeng Luang NP, Kaeng So Pha Waterfalls , 200-250 m, on tree trunk in dry deciduous forest close to a stream; 1 female; 2.5.2001; leg. P. Dankittipakul.

ETYMOLOGY: The Latin adjective “serratus -a, -um” (= saw like, serrated, saw toothed), refers to the serrated margin of the baso-median process on the TA of the male palp.

DIAGNOSIS: Hersilia serrata sp. n. clearly belongs to a presumably monophyletic clade consisting of 10 closely related species known as the savignyi -group. The male palpal patella of the savignyi -group is characterized by the presence of an elevated dorsal projection carrying minute erect spines (Fig. 15). The male of H. serrata sp. n. is distinguished from other members of the savignyi -group by the serrated basomedian process of the TA; females by the very broad and heavily sclerotized apices of the bulbose sacs of the spermathecae.

DESCRIPTION

Male holotype: Prosoma 2.5 long, 2.4 wide; opisthosoma 4.0 long, 2.5 wide. PLS 6.9 long, bS 0.9 long, tS 6.0 long.

Prosoma: Prosoma almost disc-shaped, as long as wide, with distinct clypeal projection; ocular region relatively low; clypeus about half length of ocular region; chelicerae elongated, slightly less than two times longer than wide; sternum triangular, anterior margin with shallow median incision.

Eye size and interdistances: AME distinctly larger than PME; ALE = PLE> PME; eye ratio: 1.0: 0.80: 0.38: 0.88. AME = 1.0; AME-AME = 0.48; AME-ALE = 0.68; PME = 1.0; PME-PME = 0.62; PME-PLE = 0.84.

Opisthosoma: Opisthosoma ovoid, longer than wide, widest in the middle, posteriorly with triangular anal tubercle; dorsum with four pairs of large circular DMP, second pair largest, first and fourth pairs subequal, slightly smaller than third pair; VMP numerous, forming parallel longitudinal lines but distinctly narrower posteriorly.

Spinnerets: PLS elongated, slightly less than twice as long as opisthosoma; other spinnerets slightly shorter than bS.

Leg measurements: I, 21.64 (5.50, 1.24, 5.82, 8.1, 0.98); II, 22.08 (5.8, 1.1, 5.96, 8.2, 1.02); III, 5.60 (1.84, 0.58, 1.12, 1.32, 0.74); IV, 12.96 (4.88, 0.96, 2.92, 3.22, 0.98).

Hersilia serrata sp. n., holotype (15-17), paratype (18-19). (15) Left male palp, prolateral view. (16) Ditto, ventral view. (17) Ditto, retrolateral view. (18) Epigyne, ventral view. (19) Vulva, dorsal view. Scale lines = 1.0 mm.

Male palp (Figs 15-17): Patella with dorsal projection carrying several short spines. Tibia prolaterally with bifurcated apical portion. Cymbium slender, with three stout apical spines. Bulbus almost globular, posteriorly narrowed. Embolus slender, linear, apex slightly curved, pointing downwards. TA with two processes: baso-median process strongly sclerotized, with bifurcated projection and serrated margin; apico- retrolateral process with columnar membrane situated apically, and with larger, concave, sclerotized part situated retrolaterally, its apex sharply pointed, directed mesad.

Female paratype (from Chiang Mai): Prosoma 2.8 long, 2.6 wide; opisthosoma 4.2 long, 2.6 wide. PLS 7.52 long, bS 1.10 long, tS 6.42 long.

Prosoma: Prosoma circular, clypeal area protruded, frontal clypeal margin semicircular; ocular region relatively low; clypeus approximately of same height as ocular region; chelicerae elongated, almost twice as long as wide; sternum triangular, anterior margin with shallow median incision.

Eye size and interdistances: Eyes almost subequal; AME largest> ALE = PLE> PME; ratio: 1.0: 0.94; 0.28; 0.90. AME = 1.0; AME-AME = 0.48; AME-ALE = 0.66; PME = 1.0; PME-PME = 0.68; PME-PLE = 0.88.

Opisthosoma: Opisthosma longer than wide, widest posteriorly, triangular anal tubercle indistinct; dorsum with four pairs of large circular DMP, fourth pair slightly smaller, others subequal; VMP numerous, forming V-shaped longitudinal lines.

Spinnerets: PLS elongated, slightly longer than opisthosoma; other spinnerets shorter than bS.

Leg measurements: I, 21.18 (5.10, 2.02, 5.20, 7.98, 0.88); II, 21.32 (5.62, 1.02, 5.66, 8.1, 0.98); III, 5.02 (1.66, 0.48, 1.02, 1.22, 0.64); IV, 12.4 (4.66, 0.88, 2.86, 3.12, 0.88).

Epigyne and vulva (Figs 18-19, 30): Epigyne an elevated membranous mound, posteriorly slightly higher than in anterior region, posterior margin with deep median incision; oval copulatory orifices situated medially, its margin rebordered, with reddish bands directed obliquely in antero-prolateral and antero-retrolateral direction. Vulva with broad and thickened insemination ducts, directed anteriad, then descending laterad. Receptacula widely separated, ovoid, with tubular stalks. Bulbose sacs of spermathecae rectangular, inclined towards each other, with digitiform pilose apices.

TAXONOMIC REMARKS: Males of the new species closely resemble those of H. nentwigi Baehr & Baehr, 1993 (known from Sumatra, Java and Krakatau) in the general shape of the male palp and the possession of baso-median and apico-retrolateral processes on the TA (Fig. 16). Males of both species can be distinguished by the apico-retrolateral process provided with an elongated apical membranous portion directed distad (Figs 16-17) (columnar in ventral view, beak-shaped in retrolateral view in H. serrata sp. n., but completely absent in H. nentwigi ), and by the sclerotized basomedian process with a serrated margin (carrying a bifurcated projection in H. serrata sp. n., Fig. 15, serrated area absent in H. nentwigi ). The TA of the male palp also closely resembles that of H. feai Baehr & Baehr, 1993 (from Burma) in having an elongated membranous part and a sclerotized, beak-shaped projection directed mesad on the apico-retrolateral process of the TA (Fig. 16); the TA of the new species can be distinguished by the baso-median process being triangular and lacking a bifurcated projection. Males of H. striata Wang & Yin, 1985 (from China, Myanmar, Thailand to Java and Sumatra) differ from males of the new species by the TA without a membranous apical part on the apico-retrolateral process and by the baso-median process lacking a serrated area.

Females of the new species are most similar to those of H. nentwigi but can be distinguished by the elongated, rectangular bulbose posterior sacs of their spermathecae which are provided with broad, bluntly pointed apices (Figs 19, 30) (apices and bulbose sacs not visible in H. nentwigi ). Females clearly differ from those of H. simplicipalpis (from Khao Yai NP and Doi Suthep-Pui NP) and H. striata in the different shapes of their vulvae: large bulbose sacs are present in H. simplicipalpis , thickened bulbose sacs in H. striata .

DISTRIBUTION: Northern Thailand (Chiang Mai and Phitsanulok Provinces) .