A new species of the genus TyloridaSimon, 1894 (Araneae: Tetragnathidae) from a rocky outcrop in the northern Western Ghats, India

Siddharth Kulkarni

Zoology Department, Yashavantrao Chavan Institute of Science, Satara, Maharashtra 415001, India

sskspider@gmail.com

Abstract: A new species Tylorida sataraensis sp. nov. is described from the northern Western Ghats based on female only. Its behaviour of holding under water in response to disturbance is discussed.

Keywords: New species, Satara,Tylorida, Western Ghats.

Abbreviations: AME - Anterior median eyes; CD - Copulatoryduct; FD - Fertilization duct; MOA - Median ocular area; ZSI - Zoological Survey of India.

doi: http://dx.doi.org/10.11609/JoTT.o3606.5558-61 | ZooBank:urn:lsid:zoobank.org:pub:7CDB5A97-C7DB-452F-9BB8-0C5A9F071E9F

Editor: Manju Siliwal, WILD,Coimbatore, India. Date of publication: 26 March 2014 (online & print)

Manuscript details: Ms # o3606 | Received 01 May 2013 | Final received 08 March 2014 | Finally accepted 12 March 2014

Citation: Kulkarni, S. (2014).A new species of the genus Tylorida Simon, 1894 (Araneae: Tetragnathidae) from a rocky outcrop in the northern Western Ghats, India. Journal of Threatened Taxa 6(3): 5558–5561; http://dx.doi.org/10.11609/JoTT.o3606.5558-61

Copyright: © Kulkarni 2014. Creative Commons Attribution 3.0 UnportedLicense. JoTT allows unrestricted use of this article in any medium, reproduction and distribution by providing adequate credit to the authors and the source of publication.

Funding: Research seed money from Yashavantrao Chavan Institute of Science, Satara.

Competing Interest: The authors declare no competing interests.

Acknowledgements: My sincere thanks to Dr.Fernando Alvarez-Padilla for taking personal interest in guiding me all about Tylorida; Dr. Aparna Watve for the initial encouragement to study spiders from rocky outcrops; Dr. Hemant Ghate and Dr. Akio Tanikawa for helpful discussions.

For figures, images -- click here

The genus Tylorida is, represented by nine species worldwide, of which two species T. culta (Cambridge, 1869) and T. ventralis(Thorell, 1877) are reported from India and Sri Lanka. T. ventralis has a wide distribution that extends from India to Taiwan, Japan and New Guinea while T. culta is limited to India and Sri Lanka (Platnick2013). The genus is recognized by the presence of smooth trichobothria on femur IV, and by copulatory and fertilization ducts running parallel before entering the spermathecae(Alvarez-Padilla & Hormiga 2011). The dorsum is slightly raised distally in T. ventralisto which Tikader (1982, fig. 169) refers as ‘indistinct caudal tubercle,’ but is absent in T. culta.

Rocky outcrops are basalt/ferricrete rocks exposed landform ranging from cliffs, inselbergs, and to rocky hills (Porembski& Barthlott et al. 2000). These were recently reviewed by Watve (2013) stating that these are specialized habitats accommodating a rich diversity of flora and fauna and a site for active speciation. Geomorphologically, these belong to the category of high level ferricretes in the northern Western Ghats. The maximum altitude of the plateau is 1200m, and these are surrounded by hill slopes which drop to a valley at about 800m.

Methods

The present area of study is a group of rocky plateaus in Chalkewadi region (17.57⁰N & 73.83⁰E) in Satara District, Maharashtra (Fig. 1). Spiders were collected from the webs constructed over streams flowing along the slopes of plateaus and studied under Olympus (MSZ-B) stereomicroscope. All the lengths are in millimeters. Epigyne were dissected and cleared in 10% warm KOH for 25 minutes before drawing. All specimens are deposited at the Western Regional Station, Zoological Survey of India, Pune.

Tylorida sataraensis sp. nov.

(Images 1–5, Figs. 2–4)

urn:lsid:zoobank.org:act:A477CA6F-7EDF-4FED-AF3A-396AAF37D1BA

Specimens examined: Holotype: ZSI-WRC-Ar/439, 06.iii.2013, female, Chalkewadi, coll. S. Kulkarni. Paratypes: ZSI-WRC-Ar/440, 12.i.2012, four, females, Chalkewadi, coll. S. Kulkarni & A. Sargar(single accession number for all paratypes).

Diagnosis: The new species can be distinguished from all other Tylorida species by the narrow tip at the apex of the spermatheca (fig. 3) (which is absent in all other Tylorida species). It closely resembles T. ventralis (Thorell, 1877), but can be distinguished by the absence of silver striations, the caudal tubercle and the epigynal plate not quadrangular (seeTanikawa 2007, fig. 798); epigynalatrium is arch shaped (Image 4, fig.4); spermathecawith a bulbous head facing inwards but globular and bending outwards in T. ventralis (see Jäger & Praxaysombath 2009, fig.29); CD not overlapping FD but run adjacently (fig. 3) (similar arrangement seen in T. cylindrata (Wang, 1991)); two diffuse broad yellowish line on the mid-dorsum not present in T. ventralis.

Description: Holotype. A female having a total length of 10.1; carapace 3.66 long, 2.63 wide; abdomen 6.79 long, 4.04 wide. Other material: Total. 9.9–11.7; carapace 3.34-3.89 long, 2.60–3.12 wide; abdomen 6.57–7.92 long; 3.96–4.30 wide. Cephalic region and margins of thoracic region deep brown; faint yellow middle longitudinal line on cephalic part and is higher than thoracic in lateral view. Thoracic groove Y-shaped (Image 1). Median ocular area forms square and sides of each eye encircled by black patch. Clypeus about 1½ times diameter of AME. Lateral eyes placed on two slight tubercles (Image 2). Labium semicircular;endites longer than wide margined black with tips bent outwards, both brown with yellowish edges. Legs yellow with some blackish patches. Leg I about six times the length of carapace (Leg I - 21mm) and Leg III (smallest) - 9.6 mm. Ventral side of coxa IV provided with a black line at proximal half. Coxa II with black patch ventro-laterally. Trochanter with a few soft setae at distal edge ventrally. Femora IV thin and paler ventrally provided with trichobothria in proximal half. Sternum greenish-brown; roughly heart shaped, edges folded at coxae and covered with a few long setae rising even above maxillae when seen laterally. Chelicerae with three promarginal and four retro marginal denticles; fang with fine serrations on ventral side (Image 3). Abdomen slightly less than twice of the carapace. Oval and posteriorly flattened in lateral view; slightly overlapping cephalothorax. Venter black (pigment) margined by thick yellow lines covered sparsely by whitish pubescence. Epigynal plate flat; ventrally brown with black margins and resembling typical tree shaped structure (Image 4). Genital openings in shallow depression located slightly above base of tree shape (Image 5). Cuticle appreciably sclerotized as compared to walls of spermathecae which are very weakly sclerotized. CD and FD with many closely spaced coils forming a slant S-shape (and its reflection) at each respective side (fig. 3).

Male: Unknown.

Distribution: India: Satara, Chalkewadi.

Etymology

The species name is derived from the name of the district Satara, of type locality.

Discussion

The spiders build their orb-webs just above the course of streams running through the boulders (Image 6) on the high altitude rocky plateaus. These spiders are generally seen in their webs but when disturbed, they drop into the water leaving a dragline and cling to a rock surface at a depth of an inch below the surface of water waiting till the disturbances are halted. Observation of 16 specimens showed a maximum time of 14 minutes of being underwater. I could not photograph this in the field, but put a live specimen in a water filled transparent container with a stone immersed in it. When capped and overturned, the spider clung to the substratum and I observed bubbles forming along the dorsal abdomen, continuous with book lung openings. Similar field observations were reported by Gravely (1915, p. 537) in Orsinome marmorea Pocock, 1901, but, could not study it in detail.

Orsinome marmorea has been reported only once (Gravely, 1921) after its description by the author and with insufficient characters to make any reliable identification. Similar is the case with the remainder of two Indian species O. armata Pocock, 1901 and O. listeriGravely, 1921. Since, Orsinome has been recently placed as a phylogenetic sister to Tylorida(Alvarez-Padilla & Hormiga 2011) it means that these genera are closely related. This also agrees with the morphological closeness and may have mixed species; thus indicating that both groups need revision.

References

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Gravely, F.H. (1915). Notes on Habits of Indian Insects Myriapodsand Arachnids.Records of the Indian Museum XI: 483–539.

Gravely, F.H. (1921). Some Indian spiders of the family Tetragnathidae.Recordsof the Indian Museum 22: 423–459.

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Watve, A. (2013). Status review of rocky plateaus in the northern Western Ghats and Konkan region of Maharashtra, India with recommendations for conservation and management. Journal of Threatened Taxa 5(5): 3935–3962; http://dx.doi.org/10.11609/JoTT.o3372.3935-62