Anolis riparius, Chaves & Ryan & Bolaños & Márquez & Köhler & Poe, 2023

Chaves, Gerardo, Ryan, Mason J., Bolaños, Federico, Márquez, Cruz, Köhler, Gunther & Poe, Steven, 2023, Two new species of semiaquatic Anolis (Squamata: Dactyloidae) from Costa Rica, Zootaxa 5319 (2), pp. 249-262 : 257-259

Anolis riparius , new species

Holotype. UCR 5579 ( Fig 6 ) collected on 7 September 2009 by Douglas Robinson and his students; an adult male from Pacuarito river , Pacuarito 10 Km S-SW of Pérez Zeledón, 9.31390 N, - 83.77220 W, 880 masl, San José Province, Costa Rica.

Paratypes (all from Costa Rica: San José Province). Adult males: SMF 82183–82184 (collected 9 October 2002 by Axel Fläschendräger) from road between Platanillo and San Isidro, 9.31056 N; - 83.77500 W, ca. 850 masl ; SMF 92428 (collected 15 February 2010 by Gunther Köhler) from 1 km N Cedral 9.35789 N, - 83.56094 W, 1425 masl ; UCR 7893 (collected 24 August 1979 by Douglas Robinson) from I.85 Km NE Alfombra, 9.3167 N, - 83.7722 W, ca. 930 masl; MCZ-R 18171 (collected 15 December 2007 by Steve Poe and Mason J. Ryan) from Alfombra, 12 Km S-SW of Pérez Zeledón (9.31670 N, - 83.77220 W, 930 masl); MSB 95201 (collected on 10 January 2009 by Mason J Ryan and Ian Latella) from Alfombra, 12 Km S-SW of Pérez Zeledón (9.31670 N, - 83.77220 W, 930 masl) . Adult females: SMF 82185–82186 (collected 9 October 2002 by Axel Fläschendräger) from road between Platanillo and San Isidro (ca. 850 masl) ; SMF 83093–83094 (collected 9 October 2002 by Axel Fläschendräger) from near Platanillo (ca. 850 masl) ; SMF 92429 (collected 15 February 2010 by Gunther Köhler) from 1 km N Cedral (9.35789 N, - 83,56094 W, 1425 masl) ; UCR 5580 (same data of the holotype); UCR 15959 (collected 3 March 2001 by Mason J Ryan) from Mollejones (9.22930 N, - 83.64200 W, 800 masl) ; UCR 16162 (collected 2 July 2001 by Mason J Ryan) from Alfombra, 12 Km S-SW of Pérez Zeledón (9.31670 N, - 83.77220 W, 930 masl); MCZ R-186143 (collected 15 December 2007 by Steve Poe and Mason J Ryan) from Alfombra, 12 Km S-SW of Pérez Zeledón (9.31670 N, - 83.77220 W, 930 masl) ; MSB 95200 (collected 15 December 2007 by Steve Poe and Mason J Ryan) from Alfombra, 12 Km S-SW of Pérez Zeledón (9.31670 N, - 83.77220 W, 930 masl) ; UCR 16638 (collected 15 March 2002 by Franklin Aguilar) from Fila Piedras Blancas area (9.50130 N, - 83.91280 W, 900 masl) in the Zona Protectora Los Santos in the Río Savegre basin .

Diagnosis. Anolis riparius sp. nov. and A. aquaticus are the only semiaquatic Middle American anoles that have a large orange-red dewlap with yellow in males ( Fig. 6B ). Anolis riparius sp. nov. differs from A. aquaticus in possessing smaller dorsal scales of the head and body (e.g., 15–19 scales across the snout between the second canthals in A. riparius sp. nov. versus 7–14 in A. aquaticus , Fig. 5B ), and is phylogenetically distinct (see below). Anolis riparius sp. nov. is distinguished from the other Middle American semiaquatic anoles as follows: from A. robinsoni sp. nov. by male dewlap color (chocolate brown with ill-defined brick red horizontal stripes in A. robinsoni sp. nov.); from A. lionotus and A. poecilopus by male dewlap color (solid yellow-orange in A. lionotus and A. poecilopus ), lack of postcloacal scales in males (usually present in A. lionotus and A. poecilopus ), and possession of zero to three enlarged rows of middorsal scales (a broadband of 10–24 enlarged middorsal scale rows in A. poecilopus and A. lionotus ); from A. barkeri by smaller size (maximum SVL 73 mm in A. riparius sp. nov., 91 mm in A. barkeri ), presence of distinctly expanded toe pads (ratio width of expanded pads / width of distal phalanx 1.8–2.2 in A. riparius sp. nov. versus 1.4–1.6 in A. barkeri ), and presence of a single row of middorsal caudal scales (double row in A. barkeri ).

Description of the holotype ( Figure 6 ). Adult male as indicated by dewlap and everted hemipenes SVL 73.3 mm; HL 20.1 mm; HL/SVL 0.27; HW 10.7 mm; EOH 1.64 mm; IL 1.45 mm; IL/EOH.88; SLS-I 0.1; AGL 31.26 mm; FL 18.34 mm; T4L 15.95 mm; T4W 1.54 mm; TL 135.00 mm, tail complete; TL/SVL 1.84; TH 5.994 mm and TW 3.42 mm. 18 scales across the snout between second canthals; two scales separate the nasal opening from rostral scale; ten postrostral scales between supralabials; 12 supralabial scales from rostral scale to level of middle of eye; four scales separating supraorbital semicircles; 2 rows of scales separate subocular scales from supralabials; one slightly elongate superciliary scale; nine scales separating interparietal scale from supraorbital semicircles; four enlarged scales in supraocular disk; eight loreal scales in column just anterior to eye; 12 postmental scales posteriorly in contact with mental scale between infralabials; 15 scales in the loreal region; 13 rows of single scales in the dewlap (21–48 scales per row, rows somewhat irregular); seven enlarge middorsal scale row; 16 dorsal scales in 5% of SVL; 12 ventral scales in 5% of SVL; 220 scales around midbody; 15 expanded lamellae under fourth toe; 23 small middorsal caudal scales before the first large caudal scale ( Fig. 6D ). Preoccipital, enlarged infralabial, tail crest, middorsal, postcloacal scales absent; supraocular disc presents with small scales. Frontal region of head concave; scales in supraocular disc unicarinate; rostral scale with very weak cleft and overlaps mental scale; ear opening vertically ovoid; dorsal edge of ear lacks ornamentation; mental scale completely divided posteriorly and with its posterior edge convex; dewlap extends well on to chest with anterior insertion at level of anterior portion of the eye and without protruding scales at distal edge; dorsal scales strongly keeled and uniform in size; ventral scales in diagonal rows keeled and larger than dorsal scales; lateral scales homogeneous; tail is compressed and triangular in cross-section with the base taller than wide; middorsal caudal scales in single row and its size is less than three times than the adjacent scales ( Fig. 6D ); the longest toe of adpressed limb reaches anterior to eye and, supradigital scales keeled and multicarinate.

Color in Life (based on field notes and color photographs; Fig. 6A and 6B ). Dewlap yellow with orange-red horizontal streaks. Dorsal ground color olive to chestnut brown with transverse olive-green bars across dorsum down flanks extending to tail. A dirty cream-colored line extends posteriorly from the labial scales down the side of the body. Scattered small greenish spots are present on the dorsum. The dorsum and tail are marked with olive-green transverse bars. The limbs are marked with pale green to yellowish transverse bars with small punctuations.

Variation. Size of reproductive males (69.6 ± 5.3, 65.8–73.3 mm) was larger than females (58.0 ± 6.0, 49.1–65.1 mm). Table 1 shows variation in the lepidosis characters of Anolis riparius sp. nov.. Individuals exhibited little variation in coloration. Although some individuals were dark, the amount and distribution of the light bands and dots were similar among all specimens.

Hemipenis morphology. The completely everted hemipenis of SMF 92428 ( Fig. 7B ) is a stout bilobed organ. The sulcus spermaticus is bordered by well-developed sulcal lips and opens into two broad concave areas, one on each lobe. A small asulcate ridge is present. The apex is strongly calyculate, truncus with transverse folds.

Etymology. The specific epithet is an adjective taken directly from Latin ( riparius = of stream banks) about the riparian habitat of this species.

Distribution. Anolis riparius sp. nov. is known from streams in the riparian gallery forests of the Pacuar, Guabo, and Savegre river basins ( Fig. 1 ) from 100 to 1450 masl. This species inhabits lowland and premontane tropical wet forest life zones.

Ecology. Little is known about the ecology and life history of Anolis riparius sp. nov. but it seems to share lifehistory traits with A. aquaticus and A. robinsoni sp. nov.. What follows is based mainly on field observations by MJR from Alfombra and additional unnamed streams of the Rio Guabo watershed. This species may be common in small order and headwater streams but absent from some other streams within a watershed. During the day this species may be found perched on rocks and boulders along streams and can jump into the water or crawl into interstitial cracks between rocks and boulders when pursued. At night these lizards are found sleeping on moss mats, fern fronds, and other large leafy riparian vegetation, especially near the splash zone around boulders. We have also found juveniles and adults sleeping on vertical rock walls and boulders in and next to waterfalls. We have observed these lizards sleeping from 0.5 to 2.0 meters above the ground. At Alfombra on 21 December 2007 MJR and SP found a congregation of seven gravid females on the same fern-covered boulder. One meter from the sleeping females was a cluster of 6 loosely aggregated eggs that were stuck to the moss on the same large boulder.

Morphological comparisons of the two new species and Anolis aquaticus . Anolis aquaticus is the smallest species in this complex. It has fewer scales for all traits except for the number of scales between the suboculars and supralabials ( Table 1 ). Anolis aquaticus has relatively larger dorsal scales, whereas A. robinsoni sp. nov. and A. riparius sp. nov. have small, granular dorsal scales that result in a higher number of total of scales around the body (more than 160, whereas A. aquaticus has 160 or fewer). The number of scales between the second canthals is close to half in number in A. aquaticus relative to the other species ( Table 1 , Fig. 4B , 5B , 6B ), indicating the larger size of the scales in A. aquaticus . The number of small middorsal caudal scale varies between 0 to 10 in A. aquaticus ( Fig. 5C ) while the other species has more than 20 small middorsal caudal scales ( Fig. 4D and 4D ). However, the most striking feature separating one of the three species of this group is the color of the male dewlap. The red and yellow dewlap of A. aquaticus and A. riparius sp. nov. ( Fig. 5A and 6B ) contrasts with the dark brown dewlap of A. robinsoni sp. nov. ( Fig. 4B ). We did not find any difference in hemipenes morphology among A. aquaticus , A. riparius sp. nov., and A. robinsoni sp. nov. ( Fig. 7 ).

Figures

FIGURE 1. Map of Costa Rica showing collecting sites for Anolis aquaticus group. Caribbean individuals appear to be A. aquaticus, but we consider their status uncertain on geographic grounds.

FIGURE 4. A) Anolis robinsoni in life; B) Male dewlap of Anolis robinsoni (SMF 92437) in life. C) Dorsal view of head and D) Small middorsal scales in the base of the tail of paratype (UCR 2464) of A. robinsoni locate between breakpoint (a) and the first enlarge middorsal caudal scale (b). Photo A by Robert Puschendorf, B by Gunther Köhler, and C and D by Gerardo Chaves.

FIGURE 5. A) Lateral and dewlap view of Anolis aquaticus in life. B) Dorsal view of head and C) Small middorsal scales in the base of the tail of A. aquaticus (UCR 5880) locate between breakpoint (a) and the first enlarge middorsal caudal scale (b). Photo A by Steven Poe and B and C by Gerardo Chaves.

FIGURE 6. A) Dorsal body and B) dewlap views of Anolis riparius in life. C) Dorsal view of head and D) Small middorsal scales at the base of the tail of paratype (UCR 5579) of A. riparius between breakpoint (a) and the first enlarge middorsal caudal scale (b). Photos A and B by David Laurencio and C and D by Gerardo Chaves.

FIGURE 7. Hemipenes of A. robinsoni (A), A. riparius (B), and Anolis aquaticus (C). The notable differences in appearance are due to preservation artifacts (i.e., the hemipenes of A. riparius and A. robinsoni are not completely everted). Scale bar = 1 mm for all photographs. Photos by Gunther Köhler.