Leiocephalus sixtoi, Köhler, Gunther, Rodríguez Bobadilla, Marcos J. & Hedges, S. Blair, 2016

Köhler, Gunther, Rodríguez Bobadilla, Marcos J. & Hedges, S. Blair, 2016, A new dune-dwelling lizard of the genus Leiocephalus (Iguania, Leiocephalidae) from the Dominican Republic, Zootaxa 4121 (5), pp. 517-532 : 519-527

Leiocephalus sixtoi sp. nov.

Figs. 2 a–d, 3a,c, 4a,c, 5–8

Holotype. SMF 99143, an adult male from Dunas de Baní, near the village of Las Salinas, 18.21285°, -70.53131°, 5 m asl, Provincia de Peravia, Dominican Republic, collected 22 March 2014 by Marcos Rodriguez Bobadilla. Field tag number GK-5061.

Paratypes. SMF 99144–51, same collecting data as the holotype; MNHNSD 23.2193–202, same locality as the holotype but collected 6 July 2012 by Marcos Rodríguez, Luis M. Díaz, and Nils Navarro. MNHNSD 23.202, SMF 99145, 99147, 99150–51 are adult males, the remaining specimens are adult females.

Diagnosis. Leiocephalus sixtoi differs from all other congeners except L. schreibersii , L. melanochlorus , L. psammodromus , L. inaguae , and L. macropus by the presence of a lateral fold. It differs from L. melanochlorus , L. psammodromus , and L. macropus in having 3 internasals (vs. 2 in L. melanochlorus and L. macropus , and 4 in L.

psammodromus , respectively). It further differs from L. melanochlorus and L. psammodromus in having 4 lorilabial scales anterior to the enlarged subocular (vs. 5–6). Leiocephalus sixtoi differs from L. inaguae in having a Ushaped bony parietal table (vs. V-shaped in L. inaguae ), 3 or 4 enlarged postcloacal scales in males (vs. 2 in L. inaguae ), most scales on the snout posterior to the internasal scales rugose to keeled (vs. smooth in L. inaguae ), and a patternless throat in males, spots on the throat in females (vs. throat with dark streaks and bars in males and females of L. inaguae ). Leiocephalus sixtoi differs from L. schreibersii in having the scales of the lateral fold only slightly smaller than adjacent scales (vs. scales of lateral fold distinctly smaller than adjacent scales; Fig. 4 a,b), having prominent caudal crest scales in adult males (vs. caudal crest scales of moderate size, even in very large males in L. schreibersii ; Fig. 4 c,d), a pattern of dark gray bars on a grayish brown background in the region above the lateral body fold (vs. dense turquoise blue mottling with heavy suffusion of red pigment in L. schreibersii ), a darker dorsal ground color (vs. paler in L. schreibersii ), and a red iris in adult males (vs. pale grayish blue in adult male L. schreibersii ). Leiocephalus sixtoi differs further from L. schreibersii in several osteological characters as follows: in L. sixtoi the nasal process of the premaxilla reaches to mid-level of the bony external nares (vs. to level of posterior margin of the bony external nares in L. schreibersii ), lacking a constriction at the base of the nasal process of the premaxilla (vs. such a constriction is present in L. schreibersii ), and having a reduced nasalprefrontal contact that leaves the nasal processes of the frontal bone exposed (vs. nasal and prefrontal bones in contact, thereby obscuring the nasal processes of the frontal bone in L. schreibersii ).

Description of the holotype ( Figs. 5 and 6 ). Adult male, as indicated by partly everted hemipenes; SVL 87.0 mm; tail length 125.0 mm (incomplete); tail strongly compressed in cross section, tail height 12.3 mm, tail width 5.6 mm; axilla to groin distance 38.5 mm; head length 20.0 mm, head length/SVL ratio 0.23; snout length 8.2 mm; head width 14.0 mm; head height 11.1 mm; shank length 23.1 mm, shank length/head length ratio 1.16; scales on parietal and occipital regions large, rugose to wrinkled, juxtaposed; parietal eye visible; supraoculars in a single row, multicarinate, total number 6; circumorbital row complete, separating supraoculars from supraorbital semicircles; 3 overlapping superciliaries, posteriormost longest; canthals two; anteriormost canthal separated from nasal by a small scale; internasals 3, 2 in contact with rostral; postrostrals, much longer than wide; supralabials 4 to point level of mideye, supralabial series slightly sloping down after this point; 8 (right) / 6 (left) lorilabials in a single row; 4 (right) / 3 (left) lorilabials anterior to enlarged subocular; infralabials 5 to point below center of eye; 4 loreals in two rows; 1 preocular; single, large, elongate subocular scale, in contact with one supralabial; lateral temporals keeled, subimbricate; transverse count of gular scales 29 between tympanic openings; all gulars cycloid, smooth, imbricate, some slightly pointed; first pair of sublabials in contact with anteriormost infralabials; first pair of postmentals in contact medially; interparietal scale very elongate, subtriangular; parietal scales large, almost rectangular, inner pair almost equal to size of outer one; 2–3 scales between parietals and dorsal scales; dorsal scales of neck and body large, strongly keeled, imbricate, mucronate, keels mostly orientated longitudanally, with the vertebral scales forming a serrated crest that continues along body onto tail; lateral scales of neck somewhat heterogeneous in size and shape, mostly small, weakly keeled and subimbricate, granular at base lateral neck folds; lateral scales of body mostly strongly keeled, imbricate, mucronate, keels oriented obliquely upwards, becoming smaller and less keeled toward axilla and toward groin, respectively; scales of longitudinal fold mostly large, keeled, imbricate, micronate, except at lower base of fold where they are slightly smaller and less distinctly keeled; scales around midbody 68; vertebral crest scales from occiput to level of posterior margin of thigh 77; ventrals smooth, cycloid, imbricate, distinctly larger than dorsals; preauricular fringe present with 4–5 projecting scales; antegular, antehumeral, gular, longitudinal, postauricular, supra-auricular, and transverse antegular neck folds present; dorsal scales of forelimbs and hindlimbs keeled, mucronate, imbricate; scales on ventral surfaces of limbs smooth to slightly keeled, imbricate, cycloid to pointed; lamellae on Finger IV 15/16; lamellae on Toe IV 25/25; lateral caudal scales strongly keeled, mucronate, imbricate, dorsal caudal scales greatly enlarged, forming a high, serrated crest; ventral caudal scales in a double series of pointed scales, smooth on base of tail, becoming strongly keeled on middle and distal portions; posthumeral mite pocket present as 2–3 vertical folds [Type 1 of Torres- Carvajal (2007)]; postfemoral mite pocket absent; a pair of enlarged, elongate postcloacal scales present.

Coloration in life was as follows ( Fig. 7 a, b): Dorsal surface of head Olive Brown (278) with Pale Cinnamon (55) suffusions; lateral surfaces of head Army Brown (46) above, grading into Straw Yellow (53) in labial regions, and with Olive Brown (278) and Greenish Glaucous (271) splotches and suffusions; ventral surface of head Smoky White (261); dorsal surface of neck Drab (19) suffused with Salmon Color (58); dorsal suface of body Drab (19) with Raw Umber (22) longitudinal dorsolateral bands with Creme Color (12) speckles; lateral surfaces of body with Sepia (286) transverse bands and Light Bluish Gray (288) speckles; ventral surface of body Smoke Gray (266) with transverse bands composed of Medium Paris White (140) and Pratt’s Rufous (72) scales; dorsal surfaces of limbs Drab (19) with Olive Horn Color (16) speckles; dorsal surface of tail Drab (19) with Light Bluish Gray (288) and Creme Color (12) speckles; caudal crest scales Light Bluish Gray (288) with Glaucous (289) suffusions; ventral surface of tail Medium Fawn Color (257), heavily suffused with Carmine (64); iris Orange-Rufous (56).

Variation. The paratypes agree well with the holotype in general appearance, morphometrics, and scalation. The largest male (SMF 99151) in the paratype series has a SVL of 88 mm, the largest female is 70 mm SVL. Variation in selected scalation characters: SAM in 68–79 (74.2 ± 3.4); median dorsal crest scales 72–80 (75.1 ± 2.5); number of IN is 3 in all, except SMF 99147 that has 4 IN; number of lorilabials anterior to enlarged subocular 3–4 (3.7 ± 0.4); number of SPL 4; number of IFL 5–6 (5.2 ± 0.4), number supraoculars 6–8 (7.0 ± 0.8); and subdigital lamellae on Phalanges II–IV of Toe IV 25–28 (26.3 ± 0.9). Only one specimen (SMF 99147) has a complete tail with a ratio tail length/SVL of 1.64.

All specimens in the type series have a distinct series of dark grayish brown blotches on the lateral surfaces of the body (see Fig. 7 ). The ventral surface of head and neck is mostly immaculate in males, but with distinct dark spots in females. Coloration in life of an adult female (SMF 99144; Fig 7 d) was recorded as follows: Dorsal surface of head Grayish Horn Color (286) with a suffusion of Sepia (286), especially on supraoculars; lateral surfaces of head Drab (19) above, grading into Smoky White (261) in labial regions, and with Jet Black (300) blotches; ventral surface of head Smoky White (261); dorsal suface of Smoke Gray (267) with Sepia (286) paravertebral and lateral blotches with Pale Buff (1) speckles; ventral surface of body Smoky White (261) with transverse rows of Sepia (286) blotches; dorsal and lateral surfaces of limbs Grayish Horn Color (286) with Sepia (286) splotches and Pale Buff (1) speckles; ventral surfaces of limbs Smoky White (261); dorsal surface of tail Smoke Gray (267) anteriorly, grading into Ground Cinnamon (270) with Sepia (286) chevrons, bordered distally by Smoky White (261); ventral surface of tail Smoky White (261), heavily suffused with Pale Pinkish Buff (3); iris Warm Sepia (40).

The almost completely everted hemipenis of SMF 99150 ( Fig. 8 ) is a stout, medium-sized, slightly bilobed organ; sulcus spermaticus bordered by well-developed sulcal lips and opening into a broad concave area at base of apex; distal region of apex covered by large calyces, lower apex has 4–5 large flounces.

Etymology. The name sixtoi is a patronym honoring our friend and colleague Sixto Incháustegui, who has contributed substantially to our knowledge of Hispaniolan amphibians and reptiles. Sixto is professor at the Universidad Autónoma de Santo Domingo, Dominican Republic, where he teaches herpetology and history of biology. For more than 35 years, he has been involved as a major player in biological research and nature conservation on a national and international level.

Geographic distribution. Leiocephalus sixtoi is presently only known from the surroundings of its type locality ( Fig. 9 ).

Natural history notes. The habitat at the type locality is sandy dunes with low Tropical Dry Forest ( Fig. 10 ).

This dune area streches about 15 km in length with a maximum width of about 3 km. The accumulation of sand for the formation of the dunes is a product of the waves from the Caribbean Sea and a more or less steady wind blowing mostly from the same direction. These dunes reach a maximum height of about 35 m. The vegetation in the vicinity of the dunes consists mostly of trees ( Simarouba berteroana, Coccoloba uvifera, Ziziphus reticulata, and Acacia macracantha ), cacti ( Consolea moniliformis, Opuntia dillenii, Cylindropuntia caribaea, Opuntia antillana, Harrisia nashii, Lemairecereus hystrix, Pilocereus polygonus, Melocactus lemairei, and Mammillaria prolifera ), shrubs, and grasses (Anomymous 2016). The type specimens of Leiocephalus sixtoi were collected during the morning hours on and under rocks in a grassy area. As the other species in this genus, this is a diurnal, terrestrial lizard that feeds mostly on a variety of arthropods.

Designation of a neotype for Leiocephalus schreibersii ( Gravenhorst 1838) . According to Pregill (1992:51), the type material of Leiocephalus schreibersii was unlocatable, apparently deposited in the Breslau Museum (= now Museum of Natural History at Wrocław University). Upon request by G.K., the present curator of herpetology at the Museum of Natural History at Wrocław University, Andrzej Jablonski, informed us that the type of L. schreibersii is not among the specimens in the collection under his care. Therefore, we consider it to be lost. We designate SMF 26228 ( Figs. 11 and 12 ), an adult male from Saint Marc, Province Artibonite, Haiti, collected 19 April 1939 by Robert Mertens, as the neotype of L. schreibersii .

Figures

FIGURE 2. Cranial osteology of Leiocephalus sixtoi (SMF 99151): (a) dorsal view; (b) lateral view; (c) ventral view of upper cranium; (d) right mandible in lateral view. Cranial osteology of Leiocephalus schreibersii (SMF 26278): (e) dorsal view; (f) lateral view; (g) ventral view of upper cranium; (h) right mandible in lateral view. Scale bars equal 1.0 mm. Photographs by G. K.

FIGURE 4. Region of the lateral fold in (a) Leiocephalus sixtoi (SMF 99143) and (b) L. schreibersii (SMF 26132). Lateral tail surface in (c) Leiocephalus sixtoi (SMF 99143) and (d) L. schreibersii (SMF 26133). Scale bars equal 1.0 mm. Photographs by G. K.

FIGURE 5. Holotype of Leiocephalus sixtoi (SMF 99143): (a) lateral view; (b) dorsal view; (c) ventral view; (d) lateral view of head; (e) dorsal view of head; (f) ventral view of head. Scale bars equal 5.0 mm in (a – c) and 1.0 mm in (d – f), respectively. Photographs by G. K.

FIGURE 6. Holotype of Leiocephalus sixtoi (SMF 99143): (a) dorsal region (b) flank; (c) midventer. Scale bars equal 1.0 mm. Photographs by G. K.

FIGURE 7. Leiocephalus sixtoi in life. (a, b) SMF 99143 (holotype, male); (c) SMF 99150 (male); (d) SMF 99144 (female); (e) SMF 99150 (male); (d) SMF 99146 (female). Photographs by G. K.

FIGURE 8. Hemipenes of Leiocephalus sixtoi (SMF 99150): sulcate view left, asulcate view right. Scale bar equals 1.0 mm. Photographs by G. K.

FIGURE 9. Map indicating the geographic distribution of Leiocephalus sixtoi (yellow dot) and its closest relatives, L. inagua (blue) and L. schreibersii (red).

FIGURE 10. Habitat of Leiocephalus sixtoi at Dunas de Baní, near the village Las Salinas, Provincia de Peravia, Dominican Republic. Photograph by Eladio Fernández.

FIGURE 11. Neotype of Leiocephalus schreibersii (SMF 26228): (a) dorsal view; (b) lateral view; (c) ventral view; (d) lateral view of head; (e) dorsal view of head; (f) ventral view of head. Scale bars equal 5.0 mm in (a – c) and 1.0 mm in (d – f), respectively. Photographs by G. K.

FIGURE 12. Neotype of Leiocephalus schreibersii (SMF 26228): (a) dorsal region; (b) flank; (c) midventer. Scale bars equal 1.0 mm. Photographs by G. K.