Urosaurus nigricauda (COPE, 1864)
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Urosaurus nigricauda
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| Higher Taxa | Phrynosomatidae, Sceloporinae, Iguania, Sauria, Squamata (lizards) |
| Subspecies | |
| Common Names | E: Small-scaled Lizard [microscutatus] S: Roñito de Matorral Cola-negra |
| Synonym | Uta nigricaudus COPE 1864: 176 Uta nigricauda — BOULENGER 1885: 212 Uta microscutata VAN DENBURGH 1894 Uta parviscutata COPE 1900: 324 (nom. subst. pro Uta microscutata) Urosaurus nigricaudus — MITTLEMAN 1942: 157 Urosaurus microscutatus — MITTLEMAN 1942: 159 Urosaurus nigricaudus — SMITH & TAYLOR 1950: 145 Urosaurus microscutatus — SMITH & TAYLOR 1950: 145 Urosaurus microscutatus — BOSTIC 1971 Urosaurus microscutatus — RAU 1977 Urosaurus microscutatus — STEBBINS 1985: 137 Urosaurus nigricaudus — STEBBINS 1985: 238 Urosaurus nigricaudus — LINER 1994 Urosaurus microscutatus — LINER 1994 Urosaurus nigricaudus — GRISMER 1999 Urosaurus nigricaudus — COLLINS & TAGGART 2009 Urosaurus nigricauda — BÖHME & DENZER 2019 (by implication) Urosaurus nigricaudus — HEIMES 2022 Urosaurus nigricauda — HEIMES 2022 Urosaurus nigricaudus — PERALTA-GARCÍA et al. 2023 |
| Distribution | nigricaudus: Mexico (Baja California Sur, adjacent islands: Espiritu Santo, Ballena, San José, Islas Las Islitas, Las Tijeras, Isla Pardo, Islas Los Candeleros [HR 28(1)], Magdalena ?) microscutatus: USA (S California), Mexico (Baja California, Islands of San Francisco, San José, Danzante, Coronado, Carmen, San Marcos, Santa Magdalena). Type locality: San Pedro Mártir Mountains, Baja California. Type locality: Cape San Lucas, Baja California. |
| Reproduction | oviparous |
| Types | Syntypes: USNM 5307, 69419, 69420 etc (nigricaudus) Holotype: CAS-SUR 1221 (Stanford Univ. Mus. 1221) [microscutatus] |
| Diagnosis | Diagnosis: Enlarged dorsals in seven to ten rows, commencing about equal to the insertions of the fore-limbs, and extending posteriorly to the sacrum; median rows of dorsals largest, and progressively diminishing in size as they extend laterally; enlarged dorsals prominently keeled, imbricate, rounded posteriorly; seventeen to twenty-four of the largest dorsals equal to the length of head from tip of snout to posterior border of the interparietal; dorsolateral and lateral folds usually present, nearly always crested with enlarged, spinose scales; usually several lateral clusters of enlarged tubercles; frontal usually entire, sometimes transversely divided; enlarged femorals and tibials larger than any of thedorsals; ventrals mucronate on the gular fold, pectoral,andlateral areas, but rounded elsewhere. Coloration (alcoholic) of male topotype: dorsum of body, limbs, head and tail ranging from grayish to darkbrown; limbs and tail ringed with narrow bands of dark brown to black; head finely lined with dark brown; body with nine alternating short bars which extend from the dorsolateral fold to about the median line of the back; dorsal bars about two or three scales wide, and of a dark brown color, edged with pale blue posteriorly; labial regions flecked with gray, as is also the gular region save for a light central area which is a pale tan; pectoral region flecked rather heavily with gray, as are also the undersides of the limbs and tail; abdomen with two elongate sky blue patches which are partially fused medially; preanal region with a blue wash; abdominal and lateral areas necked with numerous individual scales which are a paler blue than the remainder of the body. Measurements of fifty specimens, both sexes: head length, 10.35 mm; head width, 7.75 mm; snout to vent, 42.0 mm; hind leg, 28.0 mm; tail, 66.0 mm (Mittleman 1942: 157). |
| Comment | Urosaurus nigricaudus and U. microscutatus differ consistently in male throat coloration (usually blue in microscutatus, orange to gray in nigricaudus) and other characters. However, L.L. Grismer (cited in Wiens 1993) has observed specimens that are morphologically intermediate between these two “species”. Aguirre et al. (1999) suggest to synonymize U. microscutatus with Urosaurus nigricaudus lahtelai based on genetic evidence. GRISMER (1999) also synonymized the two species based on morphological intermediates. Feldman et al. (2011) confirm the uncertain status of U. microscutatus but express concern “that U. microscutatus is being dismissed prematurely”, hence they treat it as different in their tree and range map. Distribution: see map in Feldman et al. 2011. Genome: Davalos-Dehullu et al. 2023. |
| Etymology | Named after the black (or dark) tail (Latin “niger, nigra, nigrum” = black and Latin “cauda” = tail). Note that cauda is a noun in apposition, hence it is -cauda, not -caudus as in most previous publications (see also Böhme and Denzer 2019). |
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