AMBLYRHYNCHUS CRISTATUS

AMBLYRHYNCHUS CRISTATUS

MERTENSI EIBL-EIBESFELDT, 1962

( FIGS 5O–Q, 7)

Holotype: SMF 57430 About SMF .Type locality:‘ etwa 3 km südwestlich der Wrack-Bucht der Insel Chatham, Galápagos Inseln ’ [= Isla San Cristóbal, about 3 km SW to Wreck Bay (vicinity of Puerto Baquerizo Moreno)].

Paratypes: SMF 57424–57431 About SMF , all from the type locality ; SMF 57446–57449 About SMF , from ‘ Insel James, Crab-point, südlich der Jamesbay ’ (= Isla Santiago , Crab-point , S of James Bay), but these four specimens are herein recognized as member of a distinct and new subspecies, A. c. wikelskii subsp. nov. (described below) .

Specimens examined (N = 13): San Cristóbal: SFM 57430, coll. by I. Eibl-Eibesfeldt in 1957, about 3 km SW to Wreck Bay (holotype of A. c. mertensi). SFM 57424– 57429, SFM 57431, coll. by I. Eibl-Eibesfeldt in 1957, about 3 km SW to Wreck Bay (all of them paratypes of A. c. mertensi). CAS 104665–104667 About CAS , coll. by I.L. Wiggins in 1967, N. end of James Bay. CAS 11020 About CAS , coll. by E.S. King in 1906, no exact locality. CAS-SUR 4953 , coll. by E. Heller and R. E. Snodgrass in 1900, no exact locality .

Geographic distribution: Southern (south-western) part of Isla San Cristóbal and very likely the satellite islets off the southern coast of the island ( Fig. 8). For detailed list of localities and geographical coordinates, see MacLeod et al. (2015a).

Diagnostic description: Amblyrhynchus cristatus mertensi is a medium to large-sized subspecies of marine iguana (mean SVL 301 mm, up to a maximum of 490 mm). Mature males have a relatively well-developed crest of spines and relatively pronounced conical supracephalic scales. In preservative, males have a dark grey or blackish dorsal background, with a large and irregular lighter brownish/ochre vertebral stripe. More specifically, this subspecies is also characterized by a rostral scale most often (92%) in contact with three or more adjacent supralabials, and by the lowest number of femoral pores (20.7 ± 3.5) (see also Figs 4, 5O–Q, Table 1).

Redescription of the holotype: SMF 57430 ( Fig. 6P), adult male preserved in 70% ethanol, in good condition (with exception of a short ventral incision on the left side of the belly). Left hemipenis partly everted. SVL (270 mm) shorter than tail length (430 mm). Head 48.1 mm long (HL1), 34.1 mm high and 44.1 mm wide. Fourth finger length 43.0/ 42.5 mm. Rostral scale in contact with two adjacent supra-supralabials. Anteriormost supralabials not in contact below the mental. Eleven supralabials on the right side, eight on the left side; 11 infralabials on both sides. Internasal and rostal scales separated by a row of five small granular scales. Four large, textured and conical frontonasal scales, posterior to and in contact with the internasal. Subdigital lamellae 24/24 under the third toe, 26/27 under the fourth toe; 22 femoral pores on the right side, 20 on the left side; 285 tranversal rows of minute scales at midbody. Dorsal crest well-developed, 16 spiny scales running along the dorsal side of the neck (Cnc), followed by a postnuchal gap of 11 very reduced scales (Cng), 77 spiny scales running along the dorsal side of the trunk (Cdc), then 146 scales on the dorsal side of the tail.

After 59 years of preservation in ethanol, original colour pattern relatively well preserved. Background coloration of the dorsal and lateral side of the body almost black, with an irregularly edged, wide dark brown stripe running from the shoulders to the anteriormost fifth of the tail. Head entirely dark brown. Crest spines mostly brownish, darker on the tail. Dorsal and lateral sides of limbs dark brown, hands and feet almost black. Ventrum, ventral sides of the limbs and the anteriormost part of the tail light cream (although the very dark flank colour tends to extend ventrally) and with exception of few irregular large black patches on the belly and of a remarkably contrasting large and deep black gular collar extending over the whole chest. Throat dark grey. Ventral side of manus and pes significantly darker than the rest of the ventral side.

AMBLYRHYNCHUS CRISTATUS SIELMANNI EIBL-EIBESFELDT, 1962 View in CoL

( FIGS 6E–G, 7)

Holotype: SMF 57417 About SMF . Type locality: ‘ Westküste der Insel Abington ’ [= Isla Pinta , W coast].

Paratypes: SMF 57418–57423 About SMF , all from the type locality .

Specimens examined (N = 18): Pinta : SFM 57417, coll. by I. Eibl-Eibesfeldt in 1957, W coast of the island (holotype of A. c. sielmanni). SFM 57421, 57423, coll. by I. Eibl-Eibesfeldt in 1957, W coast of the island (paratypes of A. c. sielmanni). CAS 12547 About CAS , 12548 About CAS , 12550 About CAS , 12552 About CAS , 12553 About CAS , 12555 About CAS , 12556 About CAS , 12560 About CAS , 12562 About CAS , 12565 About CAS , 12570 About CAS , 12572 About CAS , 12573 About CAS , 12579 About CAS , 12583 About CAS , coll. by J. R. Slevin and E.S. King in 1906, no exact locality .

Geographic distribution: Pinta and very likely its satellite islets ( Fig. 8).

Diagnostic description: Amblyrhynchus cristatus sielmanni is a medium sized-subspecies of marine iguana (mean SVL 249 mm, up to a maximum of 323 mm). Mature males have a moderately developed crest of spines and relatively pronounced conical supracephalic scales. In preservative, males are dark grey or blackish dorsally (with exception of the head which is lighter), marbled or speckled with small ochre dots, frequently aligning and merging to each other to form around five spindle-shaped transversal stripes along the body. More specifically, this subspecies is also characterized by a very low number of lamellae under third (22.8 ± 1.2) and fourth (26.8 ± 1.7) toes and a low number of scales along the dorsal (100.6 ± 28.4) and caudal crest (134.2 ± 9.6) (see also Figs 4, 6E–G, Table 1).

Redescription of the holotype: SMF 57417 ( Fig. 6F), adult unsexed specimen preserved in 70% ethanol, in moderately good condition, with short ventral incisions on the belly and the chest, a large patch of missing tissue on the left shoulder, and the tip of the left fourth toe being amputated. SVL (285 mm) shorter than tail length (415 mm). Head 52.3 mm long (HL1), 39.7 mm high and 43.1 mm wide. Right fourth finger length 44.4 mm. Rostral scale in contact with two adjacent supra-supralabials. Anteriormost supralabials not in contact below the mental. Ten supralabials on the right side, nine on the left side. Eleven infralabials on the right side, 12 on the left side. Internasal and rostal scales are separated by a row of five small granular scales. Three large and slightly convex frontonasal scales, posterior to and in contact with the internasal. Subdigital lamellae 23/22 under the third toe, 26 under the fourth right toe; 26 femoral pores on both sides; 261 tranversal rows of minute scales at midbody. Dorsal crest well developed, 16 spiny scales running along the dorsal side of the neck (Cnc), followed by a postnuchal gap of 15 reduced spiny scales (Cng), 78 spiny scales running along the dorsal side of the trunk (Cdc), then 118 scales on the dorsal side of the tail.

After 59 years of preservation in ethanol, original colour pattern still visible although likely darkened. Background coloration of the dorsal and lateral sides of the body blackish with dark brown/mahogany complex nebulous patterns. Nuchal region almost uniformly blackish. Dorsal and lateral side of the head brownish/ olive, the labial and periocular regions blackish. Crest spines dark olive/grey to black. Dorsal and lateral sides of the tail almost uniformly black, with exception of nebulous lighter brownish/ochre scales on the proximal third of the tail. Dorsal and lateral sides of the limbs mostly blackish. Ventrum, ventral sides of the limbs and of the tail uniformly cream/grey, with exception of a wide gular black collar and a few large black spots on the chest. Chin dark grey. Palms and soles slightly darker than the rest of the ventrum.