Transfer of two Indian Idiops spp . to the genus Heligmomerus Simon , 1892 ( Araneae : Idiopidae ) with redescription of H . barkudensis ( Gravely , 1921 )

The family Idiopidae is represented by 22 genera and 303 species in three subfamilies in the world (Platnick 2010). The members of the subfamily Idiopinae can be identified by having anterior lateral eyes situated close to the clypeal edge, well advanced from the rest of the eye group (Raven 1985). So far, only two genera of the Idiopidae, Idiops Perty, 1833 and Heligmomerus Simon, 1892 have been reported from India (Siliwal & Molur 2007; Platnick 2010). The genus Heligmomerus is an old world genus and so far eight species are known, mainly from Africa (Dippenaar-Schoeman 2002; Platnick 2010); two species have been reported from South Asia, H. taprobanicus Simon, 1892 from Sri Lanka and H. prostans Simon, 1892 from India (Siliwal & Molur 2007; Platnick 2010). Both species are known only from the type locality. The description of both the species was based on a single specimen and a few morphological characters were described, hampering comparative work. Since Simon (1892) designated a juvenile spider as the type specimen of H. taprobanicus, there is a need for collection of more information on systematics of the genus Heligmomerus from this region. During theraphosid spider surveys in Orissa in March-April 2007, many trapdoor spiders were collected from Dhenkenal, Puri, Sambalpur and Ganjam districts, all having a dorsal depression on tibia III with the anterior lateral eyes situated close to the clypeal edge. On closer examination, they were identified as Heligmomerus spp. belonging to the subfamily Idiopinae of the


INTRODUCTION
The family Idiopidae is represented by 22 genera and 303 species in three subfamilies in the world (Platnick 2010).The members of the subfamily Idiopinae can be identified by having anterior lateral eyes situated close to the clypeal edge, well advanced from the rest of the eye group (Raven 1985).So far, only two genera of the Idiopidae, Idiops Perty, 1833 and Heligmomerus Simon, 1892 have been reported from India (Siliwal & Molur 2007;Platnick 2010).
The genus Heligmomerus is an old world genus and so far eight species are known, mainly from Africa (Dippenaar-Schoeman 2002; Platnick 2010); two species have been reported from South Asia, H. taprobanicus Simon, 1892 from Sri Lanka and H. prostans Simon, 1892 from India (Siliwal & Molur 2007;Platnick 2010).Both species are known only from the type locality.The description of both the species was based on a single specimen and a few morphological characters were described, hampering comparative work.Since Simon (1892) designated a juvenile spider as the type specimen of H. taprobanicus, there is a need for collection of more information on systematics of the genus Heligmomerus from this region.
During theraphosid spider surveys in Orissa in March-April 2007, many trapdoor spiders were collected from Dhenkenal, Puri, Sambalpur and Ganjam districts, all having a dorsal depression on tibia III with the anterior lateral eyes situated close to the clypeal edge.On closer examination, they were identified as Heligmomerus spp.belonging to the subfamily Idiopinae of the  (Gravely, 1921).Journal of Threatened Taxa 2(6): 940-947.family Idiopidae (Cambridge 1890;Pocock 1900;Raven 1985).Initially, they were considered unidentified species as many characters did not match the description of H. prostans.However on reviewing the literature, it was found that Gravely (1935) had proposed the transfer of Idiops biharicus Gravely, 1915 andI. barkudensis Gravely, 1921 to the genus Heligmomerus based on the presence of a saddle-shaped dorsal depression on tibia III.This note was missed during compilation of various spider checklists and updates (Siliwal et al. 2005;Siliwal & Molur 2007;Platnick 2010).This necessitated comparison of specimens from the mainland with Idiops barkudensis from Barkuda Island as the original description of the species lacks information on spermathecae structures (Gravely 1921).One female and a few immature individuals of Heligmomerus spp.were collected from Barkuda Island and a few specimens from Sanakuda and Kalijai Islands in the Chilika Lake.Examinatation of the spermathecal structure revealed that all specimens belong to the same species.The specimens from Barkuda Island were confirmed to be Idiops barkudensis as noted by Gravely (1935), they had a saddle-shaped depression dorsally on tibia III.With this we validate the transfer of Idiops barkudensis to the genus Heligmomerus as previously proposed by Gravely (1935).The other specimens of Heligmomerus from the mainland of Orissa and other islands were confirmed to belong to H. barkudensis based on the spermathecal structure.

Copyright
The type specimens of Idiops biharicus at the Zoological Survey of India, Kolkata could not be located but based on the description of Gravely (1935), Idiops biharicus is transferred to the genus Heligmomerus.However, re-examination of the type specimens for all the known species of Idiops is recommended to validate their taxonomic position as information about the depression on tibia III is not always provided.
In this paper, we provide additional morphological characters for H. barkudensis along with illustrations and natural history notes.

MeThODS
Measurements of body parts except for the eyes were taken with a Mitutoyo TM Vernier Caliper.Eye measurements were done with a calibrated ocular micrometer.All measurements are in mm.Spermathecae were dissected and cleaned in concentrated lactic acid in 100 o C water bath for 15-20 minutes.All illustrations were prepared with the help of camera lucida attached to a CETII TM stereomicroscope by MS.Variations in measurements for female specimens are given as a range (Mean ± SD).All specimens are deposited at the Wildlife Information Liaison Development Society, Coimbatore, Tamil Nadu.
Diagnosis: This genus differs from the genus Idiops by having a smooth saddle-shaped depression on the basal half of tibia III (Pocock 1900;Raven 1985).
Distribution: Africa, India, Sri Lanka.Colour in life (Image 1): Cephalothroax greenishblack with a darker band running on either side of caput emerging from fovea, legs blackish-green and abdomen uniformly grayish-dark brown.
Carapace greenish-brown, glabrous, no hairs except for few bristles on caput, few lines of depression along interstitial ridges and laterally, weak crenulations on caput, more conspicuous near eye group and anteriolaterally, elsewhere absent or negligible.Caput with distinct mound between fovea and eyes, mound as high as ocular tubercle/ eyes (Fig. 2).Fovea deep, procurved, U-shaped.Bristles: one on clypeal edge, caput with four long ones and three long ones between the anterior eyes.
Chelicerae (Figs. 4-5, Image 4): Five teeth on promarginal and three teeth on retromarginal; a depression on retrolateral face where fang touches chelicerae; rastellum conspicuous, raised on a high triangular mound, consist of 19 thick, short spines at vertical face and up, many normal pointed spines present vertically and dorsally on chelicerae; two hairless bands running over length of dorsal surface of chelicerae.
Sternum (Fig. 3, Image 6): 3.82 long, 3.18 wide, broader between posterior coxae; yellowish-brown, elevated in center, slopping laterally, covered with long black hair; a row of long bristles present on margins, posterior angle blunt but not separating coxae IV.
Legs: Posterior pair of legs thicker than anterior pairs; reddish-brown above and light yellowish-green below, except tarsi of palp and metatarsi and tarsi of all legs that are blackish-brown above and brown below; femora III  line; covered with short black hair with few long bristles mid dorsally, cuticle appears leathery and a little rough.Ventrally yellowish-green, uniformly covered with short and long black hairs.Spinnerets (Fig. 9, Image 8): PMS digitiform covered with brown hair; PLS covered with brown hair, apical segment dome-shaped.
Spermathecae (Fig. 10, Image 9): A pair of spermathecae, emerging from anterior ends of a triangular plat like sclerotized structure, apical ends of spermathecae rounded like a mushroom placed on a stalk.

Natural history
The forest from where these spiders were collected was primarily of dry or moist deciduous type.Specimens were also found in plantations and in degraded secondary scrubs as observed on the islands of Chilika.Spider burrows were mainly found on roadside bunds, either in open slopes or with partially overhanging vegetation.On the islands, burrows were also located at the base of trees or shrubs, or between rocks, and at times on termite mounds.
The spider burrows were simple, tubular, with a thick lining of silk, measuring 35-60 mm in length and 12-15 mm in diameter (Images 10-11).The entrance to the burrow had a single hinged door, which was round and measured 16-18 mm in diameter.The entrance door on the outer side was usually covered with mosses, leaf and or soil particles, while on the inner side it was lined with silk which was slightly thicker towards the center than along the edges.
: © Manju Siliwal, Sanjay Molur & Robert Raven 2010.Creative Commons Attribution 3.0 Unported License.JoTT allows unrestricted use of this article in any medium for non-profit purposes, reproduction and distribution by providing adequate credit to the authors and the source of publication.Author Details: Manju Siliwal is an arachnologist working with Wildlife Information Liaison Development Society since 2002.She is working on ecology, taxonomy and conservation of mygalomorph spiders of India.Sanjay Molur is the Founder Secretary of WILD and Executive Director of ZOO.He is currently involved in studies on rodents and bats in Coorg.He is also involved in trade and ecological studies of mygalomorph spiders in India since 2000.robert raven is Head of Terrestrial Biodiversity at Queensland Museum.He is one of the leading arachnologists of the world.His main interest lies in studying mygalomorph spiders.