Rhinatrema shiv Gower, Wilkinson, Sherratt & Kok, 2010
|Species Description: Gower DJ, Wilkinson M, Sherratt E, Kok PJR 2010 A new species of Rhinatrema Dumeril & Bibron (Amphibia: Gymnophiona: Rhinatrematidae) from Guyana. Zootaxza 2391:47-60.
Rhinatrema shiv is a caecilian with a total body length range of 127 - 184 mm for female and males 131 - 167 mm. It has a head that dorsally is more V-shaped than U-shaped, with a head width ranging from 4.0 - 5.2 mm. Ventrally, the lateral edges of the mandibles are inset, this is more visible anteriorly. The distance from the corner of the mouth to the top of the head is about twice the distance to the bottom. Their eyes are closer to the lips than to the top of the head with the distance between the eyes and lips about twice the diameter of the eye. Dorsally, the eye is less than one eye diameter from the edge of the head. The eye is slightly bulging from the surface of the head with the tentacle barely visible as a small bump at the anterior margin of the clear window. They have small nares anterolateral on the snout lip that are closer to the lips than they are to the eyes, nares are barely visible dorsally but are seen clearly laterally and anteriorly (Gower et al. 2010).
Ventrally and dorsally, the first nuchal groove is barely visible as faint creases that are not aligned. The second nuchal groove is not visible dorsally, but is faint ventrally and is posterodorsally oblique in the lateral view. The posterodorsal tip is posterior to the anterior-most of five transverse grooves on the dorsal surface of the collars. The first transverse groove is faint and not extensive, while the next four cross the entire dorsal surface and reach the lateral stripe, the fourth groove crosses the lateral stripe on the left. The third nuchal groove is narrowly incomplete at the mid-ventrum, behind this the anterior-most annular groove is complete. Almost all annular grooves are orthoplicate and the posterior-most four have a slight anteromedial curvature. The terminal annulus is about as long as the preceding annuli. There is a single row of large rounded subquadrangular scales mid-dorsally in deep pockets at the 12th annulus anterior to the tip. At the 10th annulus behind the collars, a single row of smaller scales is present in pockets about one annulus deep (Gower et al. 2010).
On the edge of a dilated vent there is a pair of small papillae. The phallus of the holotype is about 7 mm long. The terminal surface of the distal end of the phallus is shaped as an isosceles trapezium wider dorsally than ventrally. The phallus has a single pair of dorsolateral and ventrolateral longitudinal ridges, with the dorsolateral pair extending closer to the vent. There is a single pair of lateral longitudinal ridges with the same length as the ventrolateral pair but narrower and less prominent than both the dorsolateral and the ventrolateral pairs. There is also a single mid-dorsal and mid-ventral ridge that is wider than other ridges and is barely prominent. There are 5 - 6 lateral, 7 dorsolateral, and 5 - 6 ventrolateral longitudinal ridges with slightly raised narrow transverse bands. While the mid-dorsal and mid-ventral ridges lack transverse bands, they do have raised midline pale dots. The anterior ends of the dorsolateral ridges lead into the opening at the terminal end of the phallus and becomes smooth. The species has a major longitudinal sulcus that is homologous with other caecilians (Gower et al. 2010).
Rhinatrema bivittatum has a broader, longer and more U-shaped head than R. shiv. Rhinatrema bivittatum also has a more extensive pale blotch between the eyes, with complete pale stripes between the eye and the naris. Additionally, R. bivittatum, on average, has a larger mid-body width,about 4.2 - 10.0 mm, as well as a longer length laterally between the naris and the snout tip. Rhinatrema shiv has a mid-body width range of 5.1 - 6.2 for males and 4.7 - 5.7 mm for females, as well as a shorter distance on average from the snout tip to the corner of the mouth (Gower et al. 2010).
In preservative, R. shiv is grey-brown with off-white markings, however the body is browner where the stratum corneum is missing, and is generally darker dorsally. Ventrally, they have few pale speckles with whitish glands at the anterior margin of each annulus. Dorsally, there are slightly fewer and smaller glands at annular margins, but there are larger and more irregular pale speckles. There are few speckles on the dorsal surface of the collar. There is a pale lateral stripe that is widest at the first collar and narrower or partly broken on the second collar. The lateral stripe continues more narrowly before becoming irregular and slightly patchy on the body. At the last quarter the stripe becomes fainter and more patchy posteriorly, stopping at the vent and completely absent on the tail. The lateral stripe is absent on the back of the head but appears on the lower jaw where it insets from the lip by a distance less than the width of the stripe. The stripe is subparallel to the lateral margin of the lower jaw from behind the corner of the mouth, this stripe is prevented from contacting the opposite stripe by the narrow tapering of the brown stripe on the mentum. The stripe on the upper jaw is continuous with the margin of the mouth from its corner to the underside of the snout tip, it is widest just anterior to the eye. There are pale spots around and in front of the nares. Narrow pale areas enclose the upper half of the eye. The dorsal surface of the head is mostly grey or brown except for the symmetrical pale blotches: Behind the corner of the mouth are three markings, between the eyes there is an anteriorly open U-shape with a pale dot, and halfway between the eye and naris on each side is an irregular blotch. The lower jaw is more grey and less brown laterally behind the corner of the mouth and to the anterior of the first collar. The annuli have darker posteriors because of the pale glands and speckles are concentrated toward the anterior side of the annuli. Annular grooves are whitish and are whiter where the scale pockets are opened (Gower et. al 2010).
In life, R. shiv are brown with vivid yellow stripes and speckles (Grower et. al 2010).
There is no significant sexual dimorphism, however females tended to have more vertebrate and annuli (Grower et. al 2010).
Distribution and Habitat
Rhinaterma shiv are found in northeastern South America, specifically Kaieteur National Park, Guyana, ca. 540 m elevation and possibly Wineperu in Guyana. Contempetory specimens were collected from the submontane forest of the Pakaraima uplands on white sand dominated by clump wallaba, in pitfall traps, and in mining pits. Rhinatrema shiv are mainly found within Kaieteur National Park, however, given that a specimen was collected in Wineperu in 1979, it is possible that they could extend farther down the Essequibo drainage in Guyana (Gower et al. 2010).
Life History, Abundance, Activity, and Special Behaviors
Specimens were collected from pitfall traps and mining pits in both the long wet season from May to June, and the dry season of September. There also is evidence of nocturnal surface activity behaviors (Gower et al. 2010).
Trends and Threats
Rhinaterma shiv qualifies as “Data Deficit” on the IUCN Red List due to the lack of data on ecological tolerance and the idea that they have more than a point distribution. Because they occurred in a National park and there is a possibility that the species could be in other areas, it is possible that with further research R. shiv could be considered "Least Concern". Mining activity and habitat destruction could be considered the largest threat to the caecilian (Gower et al. 2010).
Possible reasons for amphibian decline
General habitat alteration and loss
Using pairwise differences on 1572 sites from 12S, 15S, and Cytb, it was shown that the genetic difference between R. shiv and R. bivittatum was about 15%. When the two Rhinatrema were compared to Epicrinops marmoratus and E. niger, there was a 18% difference in genetics. This data was used to support the distinction between R. shiv and R. bivittatum (Gower et al. 2010).
Rhinatrema shiv was named after Shivnarine ‘Shiv’ Chanderpaul, as recognition of being the West Indies’ most capped and highest scoring Guyanese cricketer and international cricketer of the year 2008 (Gower et al. 2010).
At the time of description, all specimens of R. shiv were fully transformed and had no indication of larval features (Gower et al. 2010).
The description of this species was the first new description of a species of rhinatrematid in 50 years. The species authority also added two caeciliid caecilians to the Guiana shield (Gower et al. 2010).
Gower, D.J., Wilkinson, M., Sherratt, E., Kok, P.J.R. (2010). ''A new species of Rhinatrema Duméril & Bibron (Amphibia: Gymnophiona: Rhinatrematidae) from Guyana.'' Zootaxa, 2391, 47-60.
Originally submitted by: Maxine Weber (first posted 2018-02-01)
Edited by: Ann T. Chang (2018-02-06)
Species Account Citation: AmphibiaWeb 2018 Rhinatrema shiv: Shiv's Rhinatrema <https://amphibiaweb.org/species/7465> University of California, Berkeley, CA, USA. Accessed Feb 21, 2024.
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Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Feb 2024.
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