Sphaerodactylus alphus, Mccranie, James R. & Hedges, S. Blair, 2013

Mccranie, James R. & Hedges, S. Blair, 2013, Two additional new species of Sphaerodactylus (Reptilia, Squamata, Gekkonoidea, Sphaerodactylidae) from the Honduran Bay Islands, Zootaxa 3694 (1) : -

Sphaerodactylus alphus sp. nov.

( Figs. 4–5 )

Sphaerodactylus rosaurae —Wilson & Hahn, 1973:106 (part). Sphaerodactylus rosaurae —Schwartz, 1975:17 (part).

Sphaerodactylus rosaurae —Schwartz & Garrido, 1981:20 (part). Sphaerodactylus rosaurae —McCranie et al., 2005:82 (part).

Holotype. FMNH 283672 (genetic sample 1, KF017633 , KF017624 ), an adult female from Savannah Bight, 16.29078°, -85.50300°, Isla de Guanaja, Islas de la Bahía, Honduras, 15 m elev., collected 20 September 2012 by James R. McCranie and Leonardo Valdés Orellana.

Paratypes (7). FMNH 283666, adult female, same data as holotype; FMNH 283663, 283674, adult males, and FMNH 283668, juvenile, from East End, 16.486°, -85.832°, collected 19 September 2012 by McCranie and Valdés Orellana; FMNH 283671, 283673 (genetic sample 2, KF017634 , KF017625 ), adult females from East End, collected 17 November 2011 by McCranie; FMNH 283664, adult male from the Hotel Posada del Sol ruins, 16.462117°, -85.853867°, collected 21 September 2012 by McCranie and Valdés Orellana.

Geographic distribution. Sphaerodactylus alphus is known to occur at low elevations on Isla de Guanaja in the Islas de la Bahía, Honduras ( Fig. 6 ).

Diagnosis. Sphaerodactylus alphus can be distinguished from S. rosaurae by its larger size (41.2 mm SVL in two of the seven adults versus maximum known SVL 38.5 mm in 26 adult S. rosaurae ; mean SVL 38.6 mm in seven adults larger than largest known female [38.5 mm] of S. rosaurae ). Sphaerodactylus alphus also differs from S. rosaurae in having a white spot enclosed in a dark brown occipital blotch that is especially distinct in adult females and juveniles, dark brown occipital blotch confluent with a narrow dark brown crossband in adult females and juveniles, and conspicuous dark, medially broken, crossbands in adult females (versus no white occipital spot, no dark brown occipital blotch confluent with narrow dark brown crossband, and dorsal pattern of adult females reduced to dark spots in S. rosaurae ). Sphaerodactylus alphus also averages more dorsal scales in males (29–35, x = 31.3±3.2, n = 3) than do male S. rosaurae (21–29, x = 26.0±2.3, n = 12). Sphaerodactylus alphus occurs sympatrically with one other species of Sphaerodactylus , S. guanajae of the S. millepunctatus species group (McCranie & Hedges 2012), but is easily distinguished from that species in having 2–3 middorsal rows of granular scales that are sharply and distinctly differentiated from the much larger surrounding dorsal scales (versus all dorsal body scales of a similar size in S. guanajae ). Sphaerodactylus alphus also differs from other S. copei species group members in amount of model-corrected cytochrome b sequence divergence (6 %; Fig. 1 ).

Description of holotype. A large Sphaerodactylus with a snout-vent length (SVL) of 38.5 mm; snout-ear length (head length) 9.0 mm; head width 4.2 mm; head depth 3.6 mm; snout length 4.1 mm, snout length/eye-ear length 1.11; tail broken at estimated point of about anterior third of original tail.

Rostral with long median cleft and short posterior notch occupied by a single small scale; supranasals 1–1, dorsally confined, anterior and lateral edges straight, rounded posteriorly, in contact with nasal opening, separated from first supralabial by upper postnasal, contacting rostral above nasal opening; internasal single, occupying space equal to about half width of each supranasal; snout scales mostly flat, keeled, most juxtaposed, 11 along midline from between level of anterior edge of orbit to rostral, four per interorbital width (IOW); scales between eyes narrower than snout scales; parietal surfaces and nape covered with swollen, conical granules, about five per IOW; superciliary spine short, located at level slightly anterior to mideye; fourth supralabial lies below anterior half of eye, fifth supralabial small, lying below center portion of eye; third infralabial lies below anterior half of eye, fourth infralabial lies below center of eye, first infralabial largest, its length slightly less than 2.0 times IOW; mental large, about as long as wide, with oblique sutures between infralabials; postmental single; gular scales smooth, granular, juxtaposed, seven per IOW.

Dorsal scales of trunk diamond-shaped, most with raised posterior ends, keeled, juxtaposed, about two per IOW, 33 along midline between levels of axilla and groin; middorsal zone of 2–3 rows of small granular scales that are sharply demarcated from remaining dorsals; lateral scales similar to dorsals; ventrals smooth, flat, about two per IOW, 32 along midline between levels of axilla and groin; scales around midbody 40 plus 2 rows of midgranules; basal supracaudal scales oblong, flat, imbricate, keeled, about one per IOW; basal subcaudal scales oblong for first six rows, median series becoming rectangular for four rows until broken point, median series smooth, larger than supracaudals, rectangular median series aligned into single row; no pair of distinctly swollen granules at each corner of vent; subdigital lamellae smooth, 12 per side present on fourth toes, 9–10 present on fourth fingers, 43 total combined subdigital lamellae on fourth digits.

Color in life ( Fig. 4 ): dorsum with Hair Brown (119A) vertical lines and mottling separating Pale Horn Color (92) bands; nuchal crossbands alternating Hair Brown-dirty white-Hair Brown-Pale Horn Color; top of head yellowish brown with dark brown longitudinal lines to level of eyes, head posterior to eyes yellowish brown with dark brown mottling; occipital region with large Hair Brown blotch with brilliant white spot in posterior portion; lateral surface of head pale brown with dark brown vertical spots; dorsal surface of tail Pale Horn Color with Hair Brown crosslines and spots; dorsal surfaces of limbs similar to that of top of head anterior to eyes; chin and throat brown with purple tinge; belly yellowish gray; subcaudal surface and ventral surfaces of limbs brownish yellow with dark brown spots; iris Army Brown (219B) with golden brown ring around pupil.

Color in alcohol: dorsal surface of head pale brown, with medium brown lines; occipital blotch dark brown with dirty white spot located near posterior end; occipital dark blotch confluent medially with narrow (4–5 scale rows long) dark brown nuchal crossband, dark crossband followed by complete (3 scale rows long) dirty white crossband, that pale crossband followed by complete (4 scale rows long) dark brown nuchal crossband, that dark brown crossband followed by incomplete medially, brown crossband (2 scale rows long dorsolaterally), that brown crossband followed by complete dark brown (3 rows long) crossband, that dark crossband followed by complete dirty white (3 rows long) crossband, that pale crossband bordered posteriorly by complete dark brown (2 rows long) crossband that passes just anterior to forelimb insertion; dorsal surface of body with alternating brown, dark brown, pale brown, dark brown, brown, pale brown, dark brown, pale brown, and dark brown crossbands; dorsal surfaces of limbs pale brown with dark brown spots, dark brown blotches and narrow crossbands also present on hind limbs; dorsal surface of base of tail pale brown with reticulated dark brown crossbands; ventral surfaces of head, chest, and body pale brown, without markings except for dark brown spots along lateral edges of belly; basal subcaudal surface pale brown with dark brown posterior edges in rectangular-shaped medial scales.

Variation. The seven adults in the type series have SVL’s of 33.2–41.2 (38.6 ± 2.7) mm, 26–35 (30.3 ± 3.0) dorsal scales, 31–32 (31.6 ± 0.5) ventral scales, 40–50 (45.6 ± 3.7) scales around midbody, 8–11 (9.6 ± 1.1) snout scales, 10–13 (12.1 ± 0.9) subdigital lamellae on the fourth toe, 8–11 (9.6 ± 1.0) subdigital lamellae on the fourth finger, 41–47 (43.4 ± 2.3) combined subdigital lamellae on fourth digits.

Color in life of an adult male paratype (FMNH 283663; Fig. 5 ): top of head Mars Brown (223A) with small white spot in posterior occipital region; dorsum of body Mars Brown with large scales greenish gray with Mars Brown edges; top of tail pale brown with extensive Mars Brown mottling and spotting; dorsal surfaces of limbs Mars Brown with dark brown spots; chin and throat Army Brown (219B); belly dark brown with some greenish gray scales; subcaudal surface grayish brown on original portion, dark grayish brown on regenerated portion; iris Mars Brown.

The adult female paratypes agree well in color in alcohol with that described for the holotype, except one (FMNH 283666) has the dorsal crossbands broken into dark brown spots forming incomplete crossbands. The adult male paratypes show distinct sexual dichromatic patterns as follows: dorsal surface of head brown without markings except for poorly-defined dark brown occipital blotch that surrounds pale brown occipital spot; dorsal surface of body brown with widely scattered dark brown spots; dorsal surfaces of limbs brown with indistinct darker brown spots; ventral surfaces of head, chest, and body pale to medium brown, without darker markings; subcaudal surface pale brown with darker brown outlining most scales. A juvenile (FMNH 283668) agrees well in color with the female holotype except the contrast between the dark and pale colors is more distinct, with the pale color being immaculate white.

Habitat. Specimens were found by raking through Sea Grape ( Cocoloba uvifera ) leaf litter and debris below coconut palms. Individuals usually tried to rapidly retreat to nearby cover when first exposed. Thus, they are somewhat difficult to capture while at the same time the collector trying not to be too aggressive because of the fragile skin of this species. Because of that fragile skin, many museum specimens of Sphaerodactylus alphus have some damage to their skin.

Etymology. The specific name alphus is a Latin masculine, singular noun meaning “a white spot on the skin.” The name alludes to the distinctive white occipital spot found in this species.

Figures

FIGURE 1. Phylogenetic tree of 11 species of Sphaerodactylus from a maximum-likelihood analysis of DNA sequences of two mitochondrial genes (12 S rRNA and cytochrome b). A scale bar is indicated. The numbers at nodes are bootstrap (left) and Bayesian (right) support values.

FIGURE 4. Adult female holotype (FMNH 283672) of Sphaerodactylus alphus sp. nov. (SVL 38.5 mm) from Savannah Bight, Isla de Guanaja, Islas de la Bahía, Honduras. Photograph by J. R. McCranie.

FIGURE 5. Adult male paratype (FMNH 283663) of Sphaerodactylus alphus sp. nov. (SVL 39.9 mm) from East End, Isla de Guanaja, Islas de la Bahía, Honduras. Photograph by J. R. McCranie. Note the sexual dichromatic differences between males and females (compare with Fig. 4) of this species.

FIGURE 6. Map of Honduras showing localities for specimens examined of Sphaerodactylus rosaurae (circles) and S. alphus sp. nov. (squares).