Gegeneophis orientalis Agarwal, Wilkinson, Mohapatra, Dutta, Giri & Gower, 2013, sp. nov.
Creators: name: Agarwal, Ishan
name: Wilkinson, Mark
name: Mohapatra, Pratyush P.
name: Dutta, Sushil K.
name: Giri, Varad B.
name: Gower, David J.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Gymnophiona
Caeciliidae
Gegeneophis
Gegeneophis orientalis

description: Gegeneophis orientalis sp. nov.
(Figs. 1, 2, 3; Table 1)
Holotype. BNHS 5413 (Fig. 2), adult female, collected near Beespuram, Visakhapatnam District, Andhra Pradesh, India (18.27 N, 82.98 E; ca. 1,170 m a.s.l.) by T. Khichi, A. D. Roy and I. Agarwal on 18 September, 2010.
Paratypes (n = 8). BNHS 5409-5410, 5412, 5414-5415, same collection data as for holotype. BNHS 5406- 5408, collected from Deomali, Koraput District, Odisha (18.64 N, 83.01 E; ca. 1,240 m a.s.l.) by S. K. Dutta and P. P. Mohapatra on 21 October, 2010. All paratypes are male except BNHS 5409.
Diagnosis. A Gegeneophis differing from all congeners in having only bicuspid teeth (see Remarks).
Description of holotype. Meristic and morphometric data in Table 1. Condition good; shallow artefactual midventral groove along much of body, two scale pockets partially opened posterodorsally, c. 25 mm long ventral incision into coelom c. 30 mm anterior to terminus, terminus slightly dented dorsolaterally. Overall shape fairly cylindrical and uniform throughout, slightly dorsoventrally compressed (midbody width 5.4 mm, height 4.6 mm). Head more V- than U-shaped in dorsal view, sides converge sharply with straight edges from CMs to level of TAs, and more sharply in front of TAs to slightly blunt snout tip. In ventral view, lower jaw and margin of mouth on upper jaw much more rounded than snout, visibility of upper jaws gradually increasing from CM to snout. In lateral view upper lip slightly concave, its apex slightly behind TA.
Eyes not visible. TAs on low, broad TPs, subcircular, a little above imaginary lines between nares and CMs; TPs but not TAs visible in dorsal and ventral views. Nares somewhat oval, approximately same size as TAs, visible in dorsal but not ventral view, clearly visible laterally, approximately equidistant from top and front and slightly further from bottom of rostrum of snout. In lateral view CMs a little closer to bottom than top of head.
All teeth of all series seemingly bicuspid. No diastemata between vomerine and palatine teeth series. Choanae subcircular, narrowest part of inter-choanal gap twice transverse width of each choana at that level. Tongue not covering IMs, unattached and elevated or thickened anteriorly; narial plugs lateral, flattened, encircled (less clearly so posteriorly) by grooves. Soft tissue at border of tongue and gum posterior to narial plugs notably swollen.
Nuchal region more massive than head, not noticeably more massive than adjacent annular region. C1 about three quarters length of C2, about one fifth longer than anteriormost annulus laterally. Nuchal grooves well marked, complete, bend anteromedially on dorsum; ventrally NG1 bends anteromedially, NG3 bends posteromedially. Single distinct and substantial (long enough to be visible laterally) TG on C2, curving anteromedially. Shorter ventral transverse crease on C1. Midventral crease extends from NG2 to near level of CMs, accompanied by a shorter paramedian crease on each side anterior to NG1.
AGs mostly well marked. Dorsally, those parts of annuli immediately anterior to and including most PAGs and SAGs raised. Single row of pale, enlarged granular glands posterior to narrow dark band of each AG, these glands generally more conspicuous posteriorly, but notably less visible from approximately first SAG back to TT, where final AGs are increasingly faint. PAGs incomplete middorsally (mostly widely) except for approximately first and last ten, incompleteness increasing gradually over anterior third of body; PAGs mostly complete or nearly so midventrally. Anteriormost SAG (on 99th PA) complete middorsally; SAGs complete midventrally only on 102nd and 103rd PA, last definitive SAG on 105th PA restricted to dorsum. Vent interrupts the 104th PAG narrowly and the 105th widely. 105th PA approximately three quarters length of 104th PA. Posterior to the 105th PAG a single, faint, dorsal, final AG, shorter than 105th PAG but longer than the last definitive SAG, further behind the 105th PAG than the distance between the last definitive secondary and either of the adjacent PAGs (the 104th and 105th) but not as far as the length of the adjacent PA (the 105th). We interpret the final AG as a PAG and thus consider there to be a small, last (the 106th) PA that lacks a SAG. Final AG approximately level with vent, distance from TT approximately 1.5 times length of 105th PA. Terminus bluntly rounded (more so than lower jaw) in ventral view, narrows from a little in front of vent. In lateral view terminus slightly upturned ventrally, strongly downturned dorsally, from in front of vent.
distance between two points. See Materials and Methods for abbreviations. *denotes holotype, other specimens are
paratypes. E = datum not recorded because of partial eversion of phallodeum. Empty cell indicates datum not recorded.
BNHS 5406-08 from Odisha, others from Andhra Pradesh.
OMs 21 24 or 26 25 22 21 19 20 19 19
IMs 4 4 4 4 4 3 or 4 3 3 or 4 4 Vent transverse, close to TT, depressed, more so centrally; four (each with partial subdivision) denticulations anterior, seven posterior, subequal in length, interdenticular grooves extending generally to edge of depression, beyond which disc (differentiated from adjacent skin primarily in colour) barely extends. No terminal keel. No anal papillae.
Scale pockets of 99th PAG very shallow dorsally; pocket of 101st slightly deeper but still less than half length of adjacent PAs. Scales in single row dorsally in both pockets, wider than long (0.5 x 0.3 mm in latter).
In preservative, body generally grey, paler anteriorly, darker posteriorly, paler ventrally except at TT. Except for posteriormost few, most AGs conspicuous, macroscopically darker than body. Midventral narrow dark grey line extends from C2 to couple of PAs in front of vent, narrower anteriorly. Body with middorsal darker stripe, darker at lateral edges than middorsally, extending to level of dorsal margin of underlying m. obliquus externus superficialis; fainter dark narrow line also along lower edge of this muscle, somewhat patchy and less clear posteriorly. Microscopically, small, circular, presumed mucous glands widespread; larger, oval, presumed granular glands relatively more common on stripe. Body with extensive pale, mainly transverse scars, mainly lateral, extending onto dorsal and/or ventral surfaces. Denticulations bordering vent mostly pale grey, outer rim of disc paler.
Head grey, generally paler than body, darker anterodorsal patch, darker lines at anterior margins of underlying m. depressor mandibulae. Snout tip and lower parts of upper jaw, including TAs, whitish. Lower jaw with broad whitish margins extending over all of mandibles from slightly behind CMs, these pale patches with darker medial edges posteriorly. Shape of m. interhyoideus visible externally via faint darker border, extends back onto front of 3rd PA.
Variation and additional information from paratypes. Some meristic and morphometric data for the paratypes are given in Table 1. Paratypes in varying states of preservation; BNHS 5412, 5414, 5415 similar to holotype; 5406–5608 in fair condition but somewhat dehydrated and browner; BNHS 5409, 5410 somewhat macerated, dark brown; 5410 partially skinned and dissected. Type series sample small and with skewed sex ratio (nine specimens, only two females) but indication of relatively shorter heads in females: L/H 28.7–29.8, mean = 29.3 versus 25.3–27.9, mean = 26.5 in males.
Little variation in head shape; upper lip slightly more concave than in holotype in BNHS 5407, 5408 and 5409; eyes not visible except faintly on right of BNHS 5415 (smallest specimen), perhaps faintly on left of BNHS 5406 and on both sides of the poorly preserved BNHS 5409, presence under bone confirmed by dissection in BNHS 5410. Prominence of TPs variable, TAs marginally visible in dorsal view in BNHS 5412, more so in BNHS 5407. Nares barely visible dorsally in BNHS 5407.
Tongue clearly observed in BNHS 5412, rounded anteriorly, plicate posteriorly, grooves around narial plugs strongest anteriorly and medially. Posteromedial plicae also visible in BNHS 5414. Swollen soft tissue at margin of tongue and gum not apparent in some specimens (e.g., BNHS 5414), and in others (e.g., BNHS 5412) it appears to be the margin of the lower jaw rather than the tongue or jaw-tongue margin that is somewhat expanded.
NG3 generally complete or nearly so, offset midventrally in BNHS 5412, perhaps slightly incomplete (at least less well-marked) midventrally in BNHS 5406, 5407, 5414. All specimens with single TG on C2. No specimen with unambiguous TG on C1 but seemingly superficial transverse creases present on some specimens, without any (BNHS 5406, 5408 and 5415) or with (BNHS 5407) some faint indication of deeper structure (and thus a little more similar to a true TG), more prevalent in drier Odisha specimens. Transverse crease on dorsal surface of C1. Transverse crease on ventral surface approximately level with CMs on ventral surface of BNHS 5412 and just behind CMs on BNHS 5414. Terminus not upturned ventrally in BNHS 5407 or 5414, vent of former specimen not depressed, vent of latter specimen somewhat distorted.
Minor variation seen in number of PAGs complete dorsally, no major outliers but drier Odisha specimens BNHS 5407 and 5408 with more dorsally complete PAGs anteriorly and posteriorly. Total range of middorsally complete PAGs approximately 5–20 anteriorly and posteriorly (24 middorsally complete PAGs posteriorly in BNHS 5407). No AGs complete posterior to vent. Posteriormost AG generally close to (slightly behind) level of vent, more posterior with shorter terminal cap in BNHS 5406. Posteriormost AGs always less distinct and shorter such that terminal cap appears larger, tending towards a terminal shield (see Kotharambath et al., 2012a) superficially, evident only upon close examination. Vent denticulations similar to holotype but interdenticular grooves sometimes extend beyond depressed area of weakly demarcated disc (e.g., BNHS 5406, 5414).
Mouth, skull, some aspects of superficial musculature, respiratory and cardiovascular systems, and scalation examined in more detail in BNHS 5410. All teeth strongly recurved. Largest OMs marginally stouter, longer than largest PMs. PMs fairly uniform, OMs notably smaller posteriorly. PMs extend by two teeth further than posterior OM on each side. Teeth of inner rows smaller than those of outer rows. VPs fairly uniform; one VP posterior to last PM on each side; VPs not on prominent ridge but posterior crowns visible laterally. IMs approximately subequal in size to VPs. Smallest interchoanal distance approximately twice width of each choana at that point. Tongue with fleshy tip, posteromedial plicae. Stapes imperforate, no separate premaxillae, septomaxillae or prefrontals, mesethmoid exposed slightly at junction of nasals and frontals. Tentacular groove roofed, entirely within maxilla. Eye under bone, almost entirely under (at far anterior end of) squamosal. Subdermal scales not found. Annular scales and pockets not found at midbody or three quarters along length of body.
Musculus depressor mandibulae composed of partially separate pars superficialis and pars profundus (sensu Wilkinson & Nussbaum, 1997), the former originating on skull bones, the latter from fascia overlying trunk muscles and more vertically oriented. Musculus interhyoideus posterior extending as far as fourth trunk myomere dorsally and just onto the seventh ventrolaterally. Musculus intermandibularis with broad origin on mandible, meeting its antimere along the ventral midline. Musculus pterygoideus small, barely visible superficially. Musculus cephalodorsosubpharyngeus lacking a distinct pars posterosuperficialis. Adjacent units of m. rectus abdominus and m. rectus lateralis separated by broad, heavily pigmented septa, antimeres of latter separated middorsally except anteriorly. Notches separating dorsal halves of adjacent units of m. obliquus externus superficialis.
The 9.9 mm long heart lies about 50 mm behind the ST, extending between the 20th and 25th AGs, the ventricle (5.5 mm) longer than the atrium (4,7 mm) and attached posteriorly to the pericardium by a cardiac ligament. The sinus venosus is horizontal; the atrium has no trace of external division; anterior pericardial space moderate (2.6 mm), conus arteriosus short (0.7 mm) with single row of valves. The elongate truncus arteriosus divides within the pericardium into an unpaired right pulmonary artery and a systemicocarotid trunk. Where the aortic arches pierce the pericardium the latter is already divided into paired, anteriorly running systemicocarotid arteries, the right larger than the left. The pulmonary artery bends sharply posteriorly and extends across the dorsal surface of the pericardium and provides a small branch to the vestigial (length 2 mm) left lung before entering the right lung (length 33 mm).
The holotype is an outlier in the paleness of its head; darker parts of head of paratypes generally greyer than more brownish body. More extensive pigmented areas of head of paratypes (including darker anteromedial patch dorsally that extends back to larger patches in front of m. depressor mandibulae) associated with more distinct pale stripe extending from TA to position expected of eye, and pale patches around TAs, ST (including nares) and margins of upper lip (e.g., BNHS 5412, 5414 and 5415). Lower jaw also more pigmented in several paratypes, most notably those from Odisha, all of which lack broad whitish areas over lateral surfaces of mandibles, instead with central dark longitudinal streak on each mandible below pale lower border to lower lip; BNHS 5410 also more like this than holotype. Denticulations more whitish in Odisha specimens. Pale scars are common on all Andhra Pradesh specimens except the almost pristine smallest specimen BNHS 5415; notably fewer scars on Odisha specimens.
Colour in life. See Fig. 3. Greyish (to grey-brown) pink, anterior of head and posterior of body more grey, posterior AGs more conspicuously whitish. Weakly indicated middorsal band darker than rest of body but also with more abundant whitish glands. Pale areas on head and body seen in preservation whitish in life. Eye visible in at least smallest specimens, inconspicuous or not visible in at least some larger specimens.
Remarks. Based on their investigations using scanning electron microscopy, Wake & Wurst (1979) reported that there is no evidence of a second cusp on the teeth of Gegeneophis ramaswamii. In contrast, Greven (1984) showed that all VPs and IMs, and most PMs of G. ramaswamii are bicuspid, and all but the posteriormost OMs are monocuspid. Our observations of the teeth of other species of Gegeneophis have been limited to light microscopy, and by small sample sizes, and in some cases it has been difficult to determine whether teeth are mono- or bicuspid. Nonetheless we are confident that we have (i) seen at least some monocuspid OMs in all other species of Gegeneophis, and (ii) never seen any bicuspid OMs in the anterior half of this series in any other Gegeneophis, Thus the presence of only bicuspid teeth provides a compelling diagnostic character for G. orientalis.
Gegeneophis orientalis also differs substantially from most of its congeners in one or more aspects of its annulation pattern. It differs from G. seshachari Ravichandran, Gower & Wilkinson, 2003, G. pareshi Giri, Gower, Gaikwad & Wilkinson, 2011, and G. primus Kotharambath, Gower, Oommen & Wilkinson, 2012 in having SAGs; from G. krishni Pillai & Ravichandran, 1999, G. goaensis Bhatta, Dinesh, Prashanth & Kulkarni, 2007, and G. mhadeiensis Bhatta, Dinesh, Prashanth & Kulkarni, 2007 in having fewer than 110 versus more than 120 PAs; and differs from G. danieli Giri, Wilkinson & Gower, 2003, G. madhavai Bhatta & Srinivasa, 2004, G. goaensis, and G. mhadeiensis in having fewer than 10 versus more than 20 PAs subdivided by SAGs. In terms of basic annulation meristics, G. orientalis is most similar to two of the three most southerly Western Ghats species, G. c a r n os u s (Beddome, 1870) and G. ramaswamii Taylor, 1964, although the relatively small differences will need to be checked when data for larger samples (especially of G. carnosus and the new species) are available. Gegeneophis carnosus has 112–119 PAs with the anteriormost SAG occurring 7–10 PAs from the terminus (n = 3, the two types plus specimen 42 reported by Gower et al., 2011), and G. ramaswamii 96–114 (mean = 102) PAs with the anteriormost SAG 7–17 (mean = 12.2) PAs from the terminus (n = 464: Presswell, 2003) versus 104–106 and 6–10 in G. orientalis respectively.
We interpret the final AG on the terminus of the holotype as a PAG and thus the last PA (the 106th) as lacking a SAG, whereas other workers might count 105 PAs and consider that there is an isolated groove (possibly a SAG) on the dorsal surface of the terminus behind the last definitive PA (e.g., Wilkinson et al., 2013). We do not think this final AG is a SAG in this case because whereas it is shorter (transversely) than the preceding definitive PAG (the 105th) it is longer than the preceding definitive SAG (against a trend of increasingly shorter SAGs over the last few preceding PAs) and because the annulus it delimits is longer (longitudinally) than would be expected if it were a SAG. Irrespective of how it is interpreted, either as a final PA that lacks any SAG preceded by PA that have SAGs or as an isolated transverse groove on a terminal cap, the phenotypic feature represents an unusual condition in caecilians and it may be worthwhile paying more attention to the grooves in this region in caecilian taxonomy.
Although G. orientalis differs from other Gegeneophis in its terminal grooves and also in a substantial dentitional feature, these do not necessitate any generic rediagnosis, and G. orientalis is otherwise, as far as we can judge, very similar to other species of Gegeneophis. With the exception of the exposure of the mesethmoid, the skull of G. orientalis appears very similar to Ramaswami’s (1943) account of that of G. carnosus and Taylor’s (1969) and Müller et al. ’s (2005) accounts of G. ramaswamii and our unpublished observations of the latter species. Features of the heart and aortic arches noted here are identical to Ramaswami’s (1944) account of them in G. carnosus. Ramaswami (1944) did not specify which localities he obtained his material from or report vouchers but, based on his other published work on Gegeneophis anatomy (e.g., Ramaswami, 1943), he likely included specimens from southernmost Kerala that would probably have been G. ramaswamii and not G. carnosus, and the features reported by Ramaswami are identical to our (MW, unpublished data) observations of the heart of G. ramaswamii.
The OMs are small posteriorly in the new species and were difficult to count. This might explain why the highest count for OMs was determined for the skinned and partly dissected specimen BNHS 5410. The possibility of underestimating tooth counts when specimens are examined without any additional preparation or techniques such as x-ray computed tomography, should be borne in mind when comparing tooth counts among different species.
The denticulations surrounding (forming the border of) the vent are greyish in several specimens. However, upon closer inspection it appears that this is not caused by pigmentation within the translucent denticulations, but by colour of internal tissues. Pigmented denticulations are seen in some other caecilian species (e.g., Chthonerpeton perrisodus: Nussbaum & Wilkinson, 1987).
Etymology. The specific epithet is an adjective derived from the Latin oriens for “East” in reference to this being the first Gegeneophis from the Eastern Ghats.
Suggested common name. Eastern Geg (English).
Distribution, conservation and natural history. In addition to the type series, a specimen was found (tissue sample only, no voucher) at Kalingakonda, Visakhaptnam District, Andhra Pradesh (17.83 N, 82.30 E; ca. 1,150 m a.s.l.) on 8 October, 2011. Gegeneophis orientalis is thus known from near Beespuram and Kalingakonda in Visakhaptnam District, Andhra Pradesh; and Deomali in Koraput District, Odisha. These localities lie in the Mahendragiri Hills of the Eastern Ghats. The Eastern Ghats comprises a discontinuous mountain range close to the east coast of peninsular India that also includes the Nallamala, Shevaroy and Malaygiri Hills and additional interior ranges (Fig. 1). The mountains in the Mahendragiri Hills form a large elevated region above 800 m and include Jindhagada (1,690 m), the highest peak in the Eastern Ghats. The high mountain tops here (above ca. 1,200 m) have flattened lateritic plateaus, reminiscent of the northern Western Ghats of Maharashtra. These plateaus are covered by grasslands with some Phoenix sp. palms, with forests restricted to riverine and sheltered areas. Most remaining forests are highly degraded and in Andhra Pradesh have been largely converted to coffee estates, predominantly without native shade trees. Mean annual rainfall is ca. 1,100 mm in Visakhapatnam District, Andhra Pradesh, 1,255 mm in Koraput District, Odisha (data for 1901–2002, http://indiawaterportal.org/met_data/).
The topotypes of G. orientalis were collected from two sites 1.5 km apart, a little below 1,200 m on slopes capped by flat grasslands (Figs. 2, 4). At both sites caecilians were found in coffee estates with native and Grevellia robusta shade trees, these sites lying in relatively sheltered depressions in sloping terrain and each with a stream. The estates where caecilians were found did not appear to be intensively maintained, and small patches of native vegetation remained at the fringes and close to streams. The caecilian at Kalingakonda was collected at 1,130 m in similar unmaintained coffee estates, while in Odisha caecilians were collected from patches of semi-evergreen forest above 1,100 m on Deomali. The soil was loose with deep leaf litter, and uropeltid snakes (Uropeltis sp.) were sympatric at all G. orientalis localities.
Gegeneophis orientalis was found by us first at the type locality in September 2010, during the late monsoon, in cool, overcast and showery conditions. The first specimen was found under a rock close to a road. In approximately 12 person hours of general herpetological searching approximately 20 G. orientalis were found across the two sites from under rocks, in leaf litter and from superficial digging of the soil (with a screwdriver, to a depth of ca. 5 cm). In drier weather in October 2011, when we revisited the type locality, we found fewer caecilians (ca. 5 in approximately 6 person hours of intensive searching for this species in the leaf litter and top few centimetres of soil). Other areas we surveyed in the area included some other coffee estates without native shade trees, the mountain-top Phoenix -grassland, as well as areas at lower elevation (<1,000 m) and no caecilians were located. In Odisha, caecilians were found beneath rocks, either just above the soil or 10–15 cm below the surface in smooth-walled, narrow, subelliptical hollows immediately below tightly fitting rocks. One animal was found in leaf litter. In Odisha, 13 G. orientalis were found in 116 person hours of post-monsoon fieldwork in September and October, 2010.
Gegeneophis orientalis is known only from above 1,100 m in habitats with canopy cover in the Mahendragiri Hills. The species appears to be tolerant of some anthropogenic disturbance, because it was locally abundant in coffee estates, but it has not been found where the canopy is open, and much forest habitat has been lost across the Mahendragiri Hills. There is one protected area that the range of G. orientalis is likely to overlap with, Paapikonda Wildlife Sanctuary in Andhra Pradesh in the mountains just south of Kalingakonda. Most other areas in the region are completely unprotected or are reserved forests with differing degrees of anthropogenic pressure. The known habitat of G. orientalis in the Mahendragiri Hills of Andhra Pradesh has been deforested and/or converted to coffee estates and there is heavy tourism pressure in the Araku Valley region. The habitat at Deomali in Odisha is being degraded rapidly through large-scale livestock grazing and fuel wood collection, and the hills in Koraput District are facing threats from mining and monoculture social forestry activities (P. Mohapatra pers. obs.).
The pale scars that are common in most of the type specimens are here interpreted as conspecific bite marks (indicative of intraspecific social behaviour) because many are V- to U-shaped, approximately the size of the mouth of G. orientalis, with long axes approximately perpendicular to the long axis of the specimens, and because they resemble scars that we have seen on captive caecilians kept in single-species community terraria with no other macroscopic animals beyond earthworms, crickets and isopods. Teodecki et al. (1998) described similar bite marks made by conspecifics in the terrestrial dermophiid Schistometopum thomense in captivity. The marks in the type series of G. orientalis are scars and the bites were thus acquired in the wild before collection.
description: Published as part of Agarwal, Ishan, Wilkinson, Mark, Mohapatra, Pratyush P., Dutta, Sushil K., Giri, Varad B. & Gower, David J., 2013, The first teresomatan caecilian (Amphibia: Gymnophiona) from the Eastern Ghats of India — a new species of Gegeneophis Peters, 1880, pp. 534-546 in Zootaxa 3696 (4) on pages 536-543, DOI: 10.11646/zootaxa.3693.4.7, http://zenodo.org/record/223530