Mesalina austroarabica, Sindaco & Simó-Riudalbas & Sacchi & Carranza, 2018

Sindaco, Roberto, Simó-Riudalbas, Marc, Sacchi, Roberto & Carranza, Salvador, 2018, Systematics of the Mesalina guttulata species complex (Squamata: Lacertidae) from Arabia with the description of two new species, Zootaxa 4429 (3), pp. 513-547 : 528-530

Mesalina austroarabica sp. nov.

( Figs. 1–5 ; Tables 1–5, Appendices I and III)

Mesalina adramitana Arnold 1980: 307 (part.); Arnold 1986a: 426 (part.); Sindaco & Jeremcenko 2008: 261 (part.); Gardner 2013: 292 (part). Mesalina ayunensis van der Kooij 2001: 20 (part.); Mesalina spec. van der Kooij 2001: 21. Mesalina guttulata Kapli et al. 2015: 6 . Mesalina sp. 1 Carranza et al. 2018.

Holotype. Adult male MCCI-R1611 , Oman, Dhofar Governorate, Jebel Samhan at 17.1161°N, 54.7131°E WGS84 (about 16 km E of Tawi Atair), 1,321 m a.s.l., 4 January 2010, R. Sindaco, C. Grieco, A. Venchi leg.

Paratypes. Two adult males and an adult female MCCI-R1624/1- 3, same locality as the holotype, 19 November 2010, R. Sindaco, C. Grieco, A. Venchi leg.; a female ( ONHM4331 ) , same locality as the holotype, 30 April 2011, S. Carranza, E. Gómez-Díaz, F. Amat leg.; a male MCCI-R1810 , Jebel Samhan at 17.1597°N, 54.8069°E WGS84, 1,594 m a.s.l. , 14 October 2013, S. Carranza, M. Metallinou, R. Sindaco, J. Šmíd, R. Vasconcelos leg.; a male NMP 6V- 74966/1 and a young NMP 6V- 74966/2 Jebel Samhan at 17.1494°N, 54.9757°E WGS 84, 233 m a.s.l., same date and collectors as MCCI-R1810.

Other specimens examined. Adult female NMP 6 V-74951, Oman, Dhofar, Jebel al Qamar at 16.8014°N, 53.2783°E, 1,076 m a.s.l., 27 December 2012, J. Šmíd, A. Chudárková leg., plus nine specimens used only for genetic analyses (no vouchers available, juvenile or damaged specimens); all listed in Appendix I.

Etymology. The species epithet “ austroarabica ” is an adjective that refers to the geographic range of its populations, distributed across southern Arabia.

Diagnosis. A small-sized Mesalina characterized by the following combination of morphological characters: (1) well-developed occipital scale in contact with the interparietal ( Fig. 5E ); (2) lower eyelid with a window made up of two large scales edged with black ( Fig. 5D ); (3) curved collar ( Fig. 5F ); (4) four upper labials in front of the subocular ( Fig. 5D ); (5) ventral plates in 8 straight longitudinal rows, the outermost much smaller (almost indistinct in MCCI-R1624) ( Fig. 5B ); (6) scales on the upper surface of the tibia keeled ( Fig. 5A ); (7) lamellae under 4th toe, 20-21; (8) dorsal coloration of adult, brown-greyish, with incomplete black-and-white ocelli (the white dots are not completely surrounded by black, but only flanked by specks on one or either sides), ordered in irregular longitudinal and transverse rows ( Fig. 5A ); (9) bluish tail in juvenile specimens.

There are no obvious diagnostic characters separating M. austroarabica sp. nov. from M. guttulata , M. bahaeldini and from the populations from the highlands of southwestern Arabia (M. sp. A in Arnold 1986a) described below. Statistical analyses (see Results above) show significant differences from M. guttulata in having smaller SVL (males), larger %HL (males and females) and larger %HW (females). Mesalina austroarabica sp. nov. shows significant differences from M. bahaeldini in having smaller SVL (males), less dorsals at midbody (males and females), and larger %HL and %forelimb length (females). Mesalina austroarabica sp. nov. shows significant differences with the populations from the highlands of southwestern Arabia (M. sp. A in Arnold 1986a) that is described herein, in having smaller SVL (males), less enlarged plates in the collar (males), less dorsals at midbody (males), less transverse rows of ventrals (males), less femoral pores (males), larger %HW (males and females), larger %forelimb length (males), larger value of Lamellae percSVL (males and females), larger %HL (females), larger %hindlimb length (females), larger %4th toe length (females).

Genetic and phylogenetic remarks. The phylogenetic analyses by Kapli et al. (2015) and the phylogenetic and nuclear network analyses performed in this study ( Fig. 2 ; Table 1) support the hypothesis that M. austroarabica sp. nov. is a different species. The level of genetic differentiation (p -distance) between the new species versus the

other members of the Mesalina guttulata species complex ranges between 3.6–6.6% in the 12S, 4.3–6.4% in the 16S and 11.7–15.7% in the cytb genes ( Table 1). A network analysis of the nuclear gene MC1R indicates that, despite the large number of samples of the M. guttulata species complex included in the analysis (36 specimens; 72 alleles), all five haplotypes (22 alleles) of M. austroarabica sp. nov. are private ( Fig. 3 ; Appendix I).

Description of the holotype. An adult male, with well-developed femoral pores, and original tail. Measurements, meristic characters and indexes: SVL = 41.5 mm, HL1 = 12.8 mm (31% of SVL), HL2 = 5.6 mm (13% of SVL), HL3 = 5.1 mm (12% of SVL), Head width = 7.0 mm (17% of SVL), Head depth = 5.0 mm (12% of SVL), pileus = 11.6 mm (28% of SVL), Forelimb length = 16.4 mm (40% of SVL), Hindlimb length = 31.4 mm (76% of SVL), 4th toe length = 9.9 mm (24% of SVL), Tail length = 93.0 mm, supralabials 8/9, subocular = 5/5, gulars = 25, enlarged plates in collar = 8, midbody scales = 39, longitudinal rows of ventrals = 8+2 (smaller), transversal rows of ventrals = 28, femoral pores = 13+13, lamellae under the 4th toe = 21. Head index = 183, Toe index = 32, Lamellae percSVL = 1.14. The two translucent scales forming the window in the lower eyelid are completely bordered by black.

Coloration in alcohol: numerous small incomplete ocelli, each one formed by 3 or 4 whitish scales forming a dot and surrounded left and/or right by a few black colored scales. These ocelli form 6-8 irregular longitudinal series and about 13 very irregular transverse series, between the fore- and hindlimbs; they further extend to the base of the tail and to the hindlimbs. These ocelli become small black and white dots on the neck and on small scales of the head. The pileus is creamy-grey with irregular blackish specks. On the sides of the head a discontinuous dark stripe is present from the upper border of the ear opening, across the eye, to the loreal scale. Another ill-defined dark stripe (that consists of a few blackish irregular spots) extends between the mid-ear opening and the subocular scale. Flanks with a more or less distinct latero-ventral whitish stripe and a usually indistinct dorso-lateral light stripe. The ventral side is creamy-white, immaculate, with the exception of the infralabial scales, which are irregularly dotted with small gray spots, as well as the outer ventrals and the anterior margin of thighs.

Variation. Quantitative variation (mensural and meristic) in the type series (n = 9) is summarized in Tables 2– 5. In one paratype (MCC-R1624/1), an additional scale separates the supranasals, and the naso-frontal scale is fragmented on the left side. The latter anomaly is present in the paratype (MCC-R1624/2) too.

Coloration in life. Ground color brownish with more or less intense shades of gray ( Fig. 5G ). In October- November, the lateral parts of the belly and sides of the head have a pink-orange hue. Tail grayish with cyan shades in young specimens; the young depicted by van der Kooij (2001: 21) has the distal half of the tail distinctly cyan.

Distribution and habitat. The species is widely distributed across more than 1,200 km in southern Arabia; from the Jebel Samhan in Dhofar to the Yemen Mountains ( Fig. 1 ). It is unknown if the distribution is continuous or discontinuous and restricted to mountains. The type locality is a flat area (possibly a filled sinkhole) close to an escarpment, very scarcely vegetated, surrounded by low rocky hills covered by shrubs. Specimens were active among stones at the base of hills’ slopes. Other syntopic reptiles are the newly described species of Tropiocolotes ( Machado et al. 2018) , Pristurus sp. 1, Pristurus carteri , Pseudotrapelus dhofarensis, Psammophis schokari (a possible predator).

Notes. Sexual maturity is probably reached with SVL ≥ 30 mm, as a male with SVL= 31 mm collected in October had femoral pores that produce secretions.

Figures

FIGURE 1. Sampling localities of the Mesalina specimens used in this study. Circles indicate samples used only in the molecular analyses, triangles indicate specimens examined and included in the morphological analyses only, and squares indicate individuals used in both molecular and morphological analyses. Colors and locality numbers correspond to Figure 2 (see also Appendix I).

FIGURE 2. Bayesian phylogenetic tree of the genus Mesalina based on concatenated sequences of three mitochondrial markers (12S, 16S and cytb) and one nuclear gene (MC1R). Black dots indicate posterior probability values ≥0.95 and bootstrap values ≥70% are shown next to the nodes. Color bars correspond to the five lineages recognized within the M. guttulata complex. Sample codes are followed by locality numbers (see Figure 1 and Appendix I). Taxon names correspond to changes proposed in this study and inset pictures show specimens of the two new species described (not to scale).

FIGURE 3. Unrooted haplotype network of the MC1R nuclear gene. Circle sizes are proportional to the number of individuals that present that particular haplotype (see Appendix I for details). White dots represent mutational steps. Colors correspond to the five lineages recognized within the M. guttulata complex.

FIGURE 4. Results of constrained correspondence analyses (CCA) for males (A) and females (B). This plot shows the position of each species included in the multivariate analyses on the first two axes of morphological space. See material and methods for details.

FIGURE 5. Pictures of the holotype of Mesalina austroarabica sp. nov. (MCCI-R1611). A) dorsal view of the body and tail; B) ventral view, C) detail of the femoral pores; D) right side of the head; E) upper (dorsal) part of the head; F) ventral (gular) side of the head; G) live specimen.