Eutropis nagarjunensis ( Sharma, 1969 )

Thasun, A. A., Campbell, Patrick D., Chandramouli, S. R., Deuti, Kaushik, Raha, Sujoy, Suranjan Karunarathna, D. M. S. & Ineich, Ivan, 2016, Taxonomy of two endemic Indian skinks, Eutropis bibronii (Gray, 1838) and E. nagarjunensis (Sharma, 1969) (Reptilia: Scincidae), including redescriptions of their types, Zootaxa 4154 (2), pp. 155-168 : 160-166

Eutropis nagarjunensis ( Sharma, 1969)

( Figs. 1–4 ; Tables 1–3 )

Mabuya nagarjuni (sic) Sharma, 1969

Holotype. Adult female, ZSI 21170 (SVL 47.5 mm), collected from Vijaypuri South near right bank of River Krishna , Andhra Pradesh, India by I.N. Maligi on 23 August 1962.

Paratype. Adult female, ZSI 21171 (SVL 48.6 mm), other details the same as holotype above.

Diagnosis. The following combination of characters distinguishes Eutropis nagarjunensis from all other Indian congeners: two dark paravertebral bands on the back, undivided lower-eyelid disc, single postnasal, 33–35 midbody scale rows, 41 paravertebral scale rows, 51 ventrals, five keels on dorsal scales, 21–24 subdigital lamellae under fourth toe, two long and one short pre-auricular lobule on each anterior tympanum, prefrontals slightly separated, two pairs of large nuchals.

Redescription of the holotype. Characters of the holotype (ZSI 21170) followed, where appropriate, by those of other examined materials (n =3) within brackets. Female, SVL 47.5 mm (SVL 46.4–48.6 mm; ZSI 24698B without head), tail broken; head moderately large, head length 27.6% of SVL (23.9–28.9%), and 55.3% of axillagroin distance (45.7–59.3%), narrow, head width 55.7% of head length (52.2–60.3%), and 15.4% of SVL (14.4– 15.1%), indistinct from neck; snout short, snout length 35.1% of head length (39.5–40.5%), snout length 63.0% of head width (67.8–75.7%), slightly concave in lateral profile; rostral shield large, hemispherical, distinctly visible from above, posterior margin of midpoint curved towards the frontonasal; frontonasal slightly separated from rostral by supranasals which are also slightly separated; frontonasal narrow, lateral border touching the anterior loreal; prefrontals slightly separated, and the frontal and the frontonasal in slight contact, distance along the longitudinal axis of frontonasal equals the prefrontals in length, lower border touching both loreal scales, the posterior border touching the first supraocular, and frontal; frontal large, elongate, subtriangular, rounded posteriorly, equal in length to combined frontoparietals and interparietal lengths; two frontoparietals in contact, distinct, equal in size with interparietal; parietals large and completely separated by interparietal, touching temporals laterally; two pairs of nuchals, overlapping middorsally behind interparietal; interparietal with grey coloured parietal eye (pineal eye). Nostril large and situated in posterior nasal; single postnasal; loreals two, anterior loreal touching supranasal, frontonasal and prefrontal; posterior loreal longer than the anterior loreal in the longitudinal axis, touching prefrontal, first supraocular and first supraciliary; presuboculars two; eye large, orbit diameter 26.7% of head length (20.7–24.6%), orbit diameter larger than tympanum-eye length, pupil rounded; interorbital distance broad; postocular one; four wide supraoculars, second is the longest in the longitudinal axis and the widest in the transverse axis and fully contacts the frontal; first supraocular in contact with prefrontal; 2nd– 4th supraoculars in contact with frontoparietals; 4th supraocular in contact with frontoparietal, parietal, and supraciliaries; three pretemporals; supraciliaries six; moveable eyelid covered with an undivided transparent disc. Supralabials six, fifth largest at mid orbit position; primary temporals three, secondary temporals three; infralabials six; ear opening deep, large, almost spherical and approximately one third of eye diameter; two long and one short pre-auricular lobule on each anterior tympanum. Mental large; a single large postmental followed by two chin shield pairs, the first pair not meeting along midline, the first chin shield in contact with second and third infralabial scales, the second pair in contact with 3rd and 4th infralabials.

E. bibronii E. nagarjunensis Nuchals multicarinate, all body scales with five keels per scale; all scales imbricate and lacking apical pits; body slender, elongate, axilla-groin distance 49.9% of SVL (48.7–52.3%); midbody scale rows 33 (33–35); paravertebral scale rows 41; ventrals 51; five enlarged precloacal scales.

Fore-limbs short, hind limbs relatively long, thigh length 14.9% of SVL (11.9–16.8%), shank length 17.7% of SVL (15.6–17.8%); thigh shorter than shank and 84.5% of shank length (76.3–97.4%); scales on the dorsal surface of fore-limbs, thigh, and shank strongly tricarinate; subdigital lamellae on toe IV, 22 (21–24); relative length of fingers: IV> III> II> V> I; those of toes: IV> III> V> II> I.

Tail broken (complete in ZSI 24698B), median scale row of subcaudals subequal, while the median row of the broken tail is enlarged and wider than antero-posterior length.

Colouration. After about 53 years in preservative fluid, dorsal head, body and limbs appear dark olive-brown. Two dark vertebral bands on the back separated by a median olive-brown band, two additional dark longitudinal bands commencing from posterior eye over tympanum and fore-limbs; another two bands between axilla and groin; all vertebral and lateral bands extend to the tail. These bands covering approximately two-scale widths in length. Lateral body and belly light brown including subcaudals.

Comparison. Congeners from India and Sri Lanka have suites of characters that distinguish them from Eutropis nagarjunensis . Eutropis nagarjunensis is most similar to E. bibronii (characters in brackets), but it can be distinguished from the latter by having broad vertebral stripes (narrow); 33–35 midbody scale rows (28–30); and 21–24 subdigital lamellae under fourth toe (15–19).

Unlike E. nagarjunensis , E. andamanensis ; E. beddomei ; E. carinata ; E. clivicola ; E. floweri ; E. gansi ; E. macularia ; E. madaraszi ; E. multifasciata ; E. quadricarinata ; E. rugifera ; E. tammanna ; E. tytleri ; and E. trivittata has a scaly lower-eyelid disc (vs. undivided and transparent eyelid disc). E. dissimilis has 47–52 paravertebrals (vs. 41). E. innotata has a single pair of nuchals (vs. two pairs). E. novemcarinata has nine keels on dorsal scales (vs. five).

John Edward Gray’s “Catalogue of the slender-tongued saurians, with descriptions of many new genera and species” was published in the journal Annals and Magazine of Natural History in three parts; two in 1838 and one in 1839. The first part was published in June 1838, the second in December of 1838 and the third in January 1839. The description of Tiliqua bibronii appeared in the second part, published in December 1838 on page 290. The date printed on the first page (page 241) at the bottom, of this issue as follows “Ann. Nat. Hist. Vol. 2 No. 10 Dec. 1838 ”. The same species based on the same type specimens, was described by A.M.C. Duméril & Bibron in “the fifth volume of Erpétologie Générale” (page 675). A.M.C. Duméril & Bibron’s publication was published on 23 November 1839 ( Bour 2012). Therefore, according to the principle of priority (Article 23) and the principle of homonymy (Article 52) of the International Code of Zoological Nomenclature (ICZN, 1999), the description of Gray (1838) has priority over that of A.M.C. Duméril & Bibron (1839).

Eutropis bibronii has long been recorded in India from the northeastern coastal plains of Orissa to the southern coastal plains of Travancore, and inland in the Eastern-Ghats ( Smith 1935, Venugopal 2010; Chandramouli et al. 2012). This skink has been reported from northeastern Sri Lanka (Jaffna, Mullaittivu, Chundikulam, Nilgala and Pollonnaruwa) by several authors (e.g. Smith 1935, Deraniyagala 1953, Somaweera & Somaweera 2009, Karunarathna & Amarasinghe 2011)—see Fig. 5 . However, our attempts to locate any Sri Lankan voucher specimens of E. bibronii proved unsuccessful. There is also the possibility that previous authors may have mistaken E. beddomei for E. bibronii as it has a very similar body colouration and is also distributed in northeastern Sri Lanka (see Amarasinghe et al. 2016). As there are no confirmed records of this species, we here remove E. bibronii from the list of Sri Lankan skinks and we consider it an endemic species to India . However, should any live specimens from Sri Lanka or any museum specimens with accurate locality records from Sri Lanka be uncovered in the future then the status of E. bibronii will have to be reassessed. Based on morphological examination of our specimens in order to obtain accurate identifications, we consider E. bibronii to be common wherever they occur. The close morphometric similarities existing between each specimen examined along with their relative distributions may indicate a morphological homogeneity between different geographic populations. Hence, we treat them as a single morphologically homogenous species distributed widely across peninsular India.

Sharma published his new species, Mabuya nagarjuni in the second issue of the first volume of the Bulletin of Systematic Zoology , Calcutta in December 1969 (printed at the top of page 71). The type locality of the species was given as “ Vijaypuri South near right bank of River Krishna ” which is close to the Nagarjuna Hills in Andhra Pradesh, India. Although Sharma (1969: 72) very clearly designated a holotype and a paratype, Srinivasulu & Das (2007) erroneously argued “ The original description did not formally designate a holotype …..”. Furthermore , they erroneously identified the original type series comprised of four specimens “…..for which reason, all four specimens from the original type series need to be considered syntypes ”. They also recovered two specimens as missing syntypes of E. nagarjunensis (see Srinivasulu & Das, 2007). However , it seems that the misleading information came from Srinivasulu et al. (2005). The phylogeography, intraspecific variation and speciation processes in the Asian genus Eutropis were investigated by Mausfeld and Schmitz (2003). However , their taxonomic rearrangement started a debate (see Datta-Roy et al. 2012). Based on morphological, morphometric, and meristic characters the closest congener of E. bibronii is E. nagarjunensis (see Figs. 1 , 2 , 4 ; Tables 2 , 3 ). Both species possess a transparent lower eyelid disc and most of their scale counts fall within very close ranges. Body colouration is also very similar except in the case of the broader black paravertebral bands which occur in E. nagarjunensis (vs. narrower bands in E. bibronii ). However , Datta-Roy et al. (2012) showed that the closest congener of E. bibronii is E. quadricarinata , and the closest congeners of E. nagarjunensis are E. trivittata and E. beddomei (see Table 2 for comparison of morphological, morphometric, and meristic characters). Furthermore , Sharma (1969) and Srinivasulu et al. (2005) considered the closest congener of E. nagarjunensis to be E. beddomei , and they provided a detailed diagnosis in order to distinguish E. nagarjunensis from E. beddomei . In their diagnosis (page 73 and page 1865 respectively), the number of lamellae beneath the fourth toe of E. nagarjunensis was stated to be within the range 16–22 (vs. 12–15 in E. beddomei ). Based on our observations from three specimens of E. nagarjunensis (including the types) we counted 21–24 lamellae, while E. bibronii has 16–19 and E. beddomei has 12–16. However, Srinivasulu et al. (2005) examined a total of 18 specimens [12 live individuals + 4 syntypes (sic) + 2 additional museum specimens] of E. nagarjunensis . Therefore, the actual range of subdigital lamellae for this species could be much wider. However, based on our observations, the difference in the number of lamellae is a major distinguishing character between E. nagarjunensis and E. bibronii (21–24 and 16–19 respectively). Therefore, we discount the lamellae count given in Sharma (1969) and Srinivasulu et al. (2005) due to its dubious nature and we provide additional evidence for the distinction of E. nagarjunensis based on the findings resulting from our examination of the type specimens as described above.

Figures

FIGURE 1. Dorsal view of the head of (A) Eutropis bibronii syntype (MNHN-RA 7076, SVL 48.5 mm), (B) E. nagarjunensis holotype (ZSI 21170, SVL 47.5 mm); lateral view of the head of (C) E. bibronii syntype (MNHN-RA 7076), and (D) E. nagarjunensis holotype, (ZSI 21170) (scale = 2 mm).

FIGURE 2. Illustration showing the comparison of dorsal head scales of (A) Eutropis bibronii syntype (MNHN-RA 7076), (B) E. nagarjunensis holotype (ZSI 21170); and E. beddomei holotype (BMNH 1946.8.19.17).

FIGURE 3. (A) A live male of Eutropis bibronii (not collected) from Hosur, Eastern Ghats, India (photo: S. R. Chandramouli); (B) A live male of E. nagarjunensis (not collected) from the type locality, Nagarjunsagar, Andhra Pradesh, India (photo: D. Adimallaiah).

FIGURE 4. Plot of (a) PC 1 vs. PC 2 and (b) PC 1 vs. PC 3 showing morphometric similarity between the taxa Eutropis bibronii and E. nagarjunensis, and their distinction from E. beddomei. Eutropis bibronii (dark blue), syntypes of Euprepis trilineatus in light blue; Eutropis nagarjunensis (green); and Eutropis beddomei (red), the circle with dot in the middle represents the examined Sri Lankan specimens.

FIGURE 5. Current distribution pattern of E. beddomei (red), E. nagarjunensis (green), and Eutropis bibronii (blue), modified after Amarasinghe et al. (2016). Note: the locations of E. bibronii depicted as from Sri Lanka are most likely result of wrong identifications.

Tables

TABLE 2. Comparison of morphological, mensural, and meristic characters of Eutropis bibronii, E. quadricarinata, E. nagarjunensis, E. trivittata and E. beddomei; “ – ” not measured.

	E. bibronii (n =25)	E. quadricarinata (n =3)	E. nagarjunensis E. trivittata (n =3) (n =2)	E. beddomei (n =21)
SVL	30.0–52.0	28.9–48.0	46.4–48.6 64.5–78.7	41.2–57.3
Head length	8.2–12.8	8.2–11.3	11.6–13.4 14.5–19.0	10.1–13.8
Head width	4.8–7.3	5.2–6.4	7.0–7.3 10.0–12.8	5.9–9.9
Snout length	3.1–5.5	2.6–3.7	4.6–5.3 4.9–6.4	3.4–4.7
Orbit diameter	1.5–3.0	1.6–2.9	2.4–3.5 3.2–5.3	1.7–4.1
Tympanum–eye length	2.1–4.8	2.5–3.0	3.0–3.1 4.5–5.8	2.6–4.5
Axilla–groin length	12.0–25.3	–	22.6–25.4 –	19.8–35.4
Thigh length	3.8–7.8	4.8–6.3	5.8–7.8 9.7–10.0	4.5–7.9
Shank length	4.2–7.7	4.1–6.0	7.6–8.4 9.3–11.0	4.5–7.9
Midbody scale rows	28–30	27–30	33–35 34–36	28–34
Paravertebrals	37–41	41–43	41 48–53	48–54
Ventrals	46–52	46–47	51 57–63	53–59
Lamellae on 4th toe	15–19	16–19	21–24 13–14	12–16
Nuchal pairs	2 (3)	1	2 (3) 1	1
Keels on middorsal scales	5	4	5 4 (5)	3 (4)
Short pre-auricular lobes	1	not visible	1 not visible	6
Long pre-auricular lobes	2	not visible	2 not visible	0
Parietals smooth (0), keeled (1)	1	1	0 0	0
Prefrontals separated (0), in contact (1)	0	0	1 1	1
Temporal scales smooth (0), keeled (1)	1	1	0 0	0
Lower-eyelid divided/scaly (0), undivided (1)	1	0	1 0	0
Dark middorsal bands narrow (0), broad (1)	0	0	1 0	0
Discussion

TABLE 3. Factor loadings and the percentage of variance explained by the principal components.

	PC 1	PC 2	PC 3
Head length	0.31	0.43	0.11
Head width	-0.13	0.59	0.02
Snout length	0.34	0.35	-0.14
Tympanum-eye length	-0.10	0.51	-0.36
Eye diameter	0.30	-0.07	0.41
Tibia length	0.37	0.07	0.27
Femur length	0.38	-0.06	-0.07
midbody scalerows	-0.22	0.25	0.72
lamellae on toe IV	0.40	-0.08	0.12
paravertebrals	-0.42	0.05	0.25
Eigenvalue	4.7 3	2.0 5	1.0 1
% variance	47.26	20.51	10.14