Dactyloa microtus Cope 1871
Creators: name: Lotzkat, Sebastian
name: Hertz, Andreas
name: Bienentreu, Joe-Felix
name: Köhler, Gunther
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Squamata
Dactyloidae
Dactyloa
Dactyloa microtus

description: Dactyloa microtus (Cope 1871)
Figures 2; 7; 16; 18T–U.
Anolis microtus: Cope (1871, 1876); Boulenger (1885); Dunn (1937: in part.); Taylor (1956: in part.); Peters and Donoso- Barros (1970: in part.); Savage (1974); Savage and Talbot (1978: in part.); Arosemena et al. (1992: in part.); Auth (1994: in part.); Poe (2004); Nicholson et al. (2005); Fläschendräger and Wijffels (2009: in part.); Hamad (2009: in part.); Castañeda & de Queiroz (2011: in part.); Lotzkat et al. (2011).
Holotype. USNM 31282, female, from Costa Rica: Provincia de San José: near San José; probably from near La Palma (Savage 1974; Fig. 1: loc. 21; Fig. 22).
Diagnosis. A large species (maximum SVL 111 mm) of the genus Dactyloa (sensu Nicholson et al. 2012) that is most similar in external morphology to the other members of this genus found in western Panama (D. casildae, D. frenata, D. ginaelisae, D. ibanezi, D. insignis, and D. kunayalae). Dactyloa microtus can readily be distinguished from these six species by its color pattern described below and shown in Figs. 2, 7, 16, and 18T–U. It further differs from all mentioned species except D. ginaelisae by its low numbers of horizontal loreal rows (4 or fewer in D. microtus vs. 5 or more) and total loreal scales (26 or fewer in D. microtus vs. 39 or more), and by its low number of scales around midbody (106 or fewer in D. microtus vs. 110 or more). Moreover, D. microtus differs from D. casildae, D. frenata, and D. ibanezi in having short legs (tip of fourth toe of adpressed hind limb reaching at most to tympanum in D. microtus vs. beyond eye; shank length/SVL = 0.183 or less in D. microtus vs. 0.25 or more). Among the short-legged species of Dactyloa in western Panama, D. microtus further differs from D. insignis in having fewer subdigital lamellae under the fourth toe (47 or fewer in D. microtus vs. 52 or more) as well as under the fourth finger (37 or fewer in D. microtus vs. 40), and from D. kunayalae in having more subdigital lamellae under the fourth toe (44 or more in D. microtus vs. 35 or fewer) as well as under the fourth finger (32 or more in D. ginaelisae vs. 25 or fewer). Dactyloa microtus is very similar to D. ginaelisae, from which it differs in having shorter legs (tip of fourth toe of adpressed hind limb reaching to a point between shoulder and tympanum in D. microtus vs. to a point between tympanum and eye in D. ginaelisae; shank length/SVL = 0.183 or less in D. microtus vs. 0.19 or more) and by its less conspicuous and clear-cut coloration pattern between eye and shoulder (light postsupralabial and dark postorbital stripe oriented rather ventrally and losing their conspicuousness around ear in D. microtus vs. a prominent light stripe extending from supralabials posteriorly above or across the ear before bending down towards shoulder, delineating a dark preaxillary blotch above and posteriorly, and paralleled above by a dark postorbital stripe with darker borders that extends at least to a level above the preaxillary blotch in D. ginaelisae). For more characters that might help to distinguish these two very similar species, see remarks section in the species account of D. ginaelisae.
Description. Total length to 331 mm; SVL to 111 mm in males, to 104 mm in females; tail long, about 1.4–1.7 times SVL, compressed, with a low dorsal crest on the anterior portion; legs short, tip of fourth toe of adpressed hind limb reaching to a point between shoulder and tympanum; dorsal and lateral head scales generally large; internasals, canthals, and loreals rugose to wrinkled; scales of frontal and prefrontal area mostly rugose to wrinkled; IP either distinct or indistinct, if discernable, then usually surrounded by scales of both smaller and equal size; parietal area generally with flat, rugose scales; parietal eye either distinct or indistinct; scales of SS distinctly enlarged, rugose; scales of supraorbital disk conspicuously enlarged, rugose; usually only one slightly elongate, keeled anterior superciliary scale, one-fourth to half as long as horizontal eye diameter, usually followed by several similarly keeled, but much shorter scales; one or two sublabials greatly enlarged, higher than INL; scales of temporal arch usually larger than those above and below; ear opening small, by far not as high as eye, less high than SPL and INL together, usually about as high as SPL; prominent nuchal and lower dorsal crest present; no rows of middorsal scales slightly enlarged; other dorsal scales as well as lateral scales smooth to slightly rugose or wrinkled in two young males, smooth in a very small juvenile, with very small granules scattered in the interspaces between them; ventrals not or only slightly larger than largest dorsals, smooth; scales on anterodorsal surface of thigh multicarinate; scales on dorsal surface of forearm multicarinate; fourth toe with well-developed dilated pad, about three times width of distal phalanx; dewlap of young males large, extending posteriorly to about one-fourth of the distance between axilla and groin, with gorgetal-sternal scale rows of densely arranged scales and widely spaced scales in the broad interspaces between the rows; dewlap of a small juvenile female moderate, extending posteriorly to slightly beyond axilla.
The hemipenis of Dactyloa microtus remains undescribed.
Coloration in life. Dactyloa microtus exhibits a rather variable coloration. Among the more reliable features usually present are dark crossbands around the tail and, mostly with light centers, on dorsal surfaces of limbs and digits; a light postsupralabial and a dark postorbital stripe extending to near the ear opening; a dark preaxillary blotch. Otherwise, dorsal and lateral surfaces with spots, blotches, and reticula that are are lighter and/or darker than ground color and partly arranged in transverse bars; dorsolateral pattern elements may reach well onto the otherwise comparably unicolor white or yellow ventral surfaces; ground and marking colors of dorsal and lateral surfaces ranging from white over different shades of yellow, green, blue, and brown to black; iris purplish blue to brown, or gray with suffusions of these colors; dewlap of young males yellowish; dewlap of a hatchling female pinkish to salmon color (Figs. 2; 7; 16; see remarks section for adult dewlap coloration reported from Costa Rica). This species is capable of considerable metachrosis (compare Figs. 16 A and B, C and D, F and H). The green phase, usually shown while the animal is sleeping, can culminate in restricting most colors to white, green, and blue, blurring some or all of the otherwise contrasting markings. Similarly, the dark or brown phase, often assumed when the animal is handled, can cause all pattern elements to assume different shades of brown. In between, most pattern elements of a given individual can apparently assume most colors from the palette of this species. A female hatchling was mostly gray when found at daytime. Color photographs of D. microtus have been published by Savage (2002). No standardized description of the coloration in life was recorded.
Coloration in preservative. After approximately two years of preservation in 70% ethanol, colors are largely reduced to white, cream, different shades of brown, and black (Figs. 18 T–U).
Geographic distribution. Dactyloa microtus is endemic to the Lower Central American, or Talamancan, highlands of Costa Rica and extreme western Panama. It occurs on both Caribbean and Pacific versants, at premontane and lower montane elevations of 1100 to probably above 2000 m asl (see remarks). In Panama, D. microtus has only been recorded from Río Changena, Bocas del Toro province, at 1640 m asl (Fig. 22).
Natural history notes. Two young males were encountered at night while they were sleeping on a leaf and a branch, 1.5 and 3 m above ground, respectively. A hatchling female virtually dropped into camp on 18 July 2010 while we detached tent strings from a tree.
Our automatized temperature recordings at Río Changena (1640 m asl) range between 13.7–19.2°C. According to our combined dataset of 12 georeferenced occurrences (after the exclusion of two localities below 1000 m asl, see remarks), the species inhabits PMMF, PMWF, LMWF, and LMRF, with temperatures between 7.2–26.4°C, mean annual temperatures of 12.2–20.4°C and a total annual precipitation of 1660–4556 mm.
Conservation. Jaramillo et al. (2010) calculated an EVS of 11 for Dactyloa microtus, which at the time also comprised the populations described herein as D. ginaelisae, and assigned that species to the IUCN category LC. We calculated the EVS for D. microtus as 4 (range) + 3 (persecution) + 5 (ecological distribution) = 12. Its extent of occurrence of just 3346 km 2 and the continuing deforestation we observed in the region qualify the species for the IUCN category “Endangered” (EN).
Remarks. All previous records of Dactyloa microtus from Panama must have been based on individuals of D. ginaelisae, considering the distribution of the two species as documented herein. Thus, our record from Río Changena is not only the first record of this species from Bocas del Toro province, but also the first and only true record from Panama. Savage (2002) and consequently Köhler (2008) gave the species’ lower distributional limit as 425 m asl. Re-examination of the underlying specimens showed them to be misidentified D. insignis, raising the lower elevational limit to about 1100 m asl in Costa Rica and thus for the species as a whole (J. M. Savage, pers. comm.). The high elevation of Cerro Dantas, provenance of the individual photographed by Daniel Cascante (Figs. 7 K–L), suggests that the species occurs well above the upper elevational limit of 1500 m asl given by Savage (2002) and Köhler (2008).
All previous authors have reported the absence of a distinct IP and parietal eye as a diagnostic character for Dactyloa microtus. However, two of our three specimens do have a well-discernable IP with parietal eye (Fig. 16 I; also see remarks concerning this matter for D. ginaelisae and D. insignis). Savage (2002) described the dewlap of adult males as “pink with white scales” or “pale salmon with several vertical rows of white scales,” and that of females as “pinkish.” Inasmuch as they are visible, the dewlaps of the adult Costa Rican specimens (Figs. 7 J and L) comply with these descriptions.
We strongly oppose against the common name “Tiny anole” assigned to this species by Frank and Ramus (1995). Since Dactyloa microtus is one of the largest mainland anoles, this common name apparently is derived from a mistranslation of the specific epithet microtus, a compound noun in apposition translating to “small ear.” If one really needs to use common instead of scientific names for whatever reason, then the correct translation “Small-ear anole” would be much more appropriate.
description: Published as part of Lotzkat, Sebastian, Hertz, Andreas, Bienentreu, Joe-Felix & Köhler, Gunther, 2013, Distribution and variation of the giant alpha anoles (Squamata: Dactyloidae) of the genus Dactyloa in the highlands of western Panama, with the description of a new species formerly referred to as D. microtus, pp. 1-54 in Zootaxa 3626 (1) on pages 39-41, DOI: 10.11646/zootaxa.3626.1.1, http://zenodo.org/record/283424