Kinosternon cora Loc-Barragán & Reyes-Velasco & Woolrich-Piña & Grünwald & Anaya & Rangel-Mendoza & López-Luna 2020, sp. nov.

Kinosternon cora sp. nov. (Figs. 1,2,3,5,6)

Cora Mud Turtle, Casquito cora, Chacuanita cora

Holotype— (JALB-391, MZFC-HE 35627) (Fig. 1), an adult female from Mexico: Sinaloa: Ejido La Concepción (La Concha), Municipio de Escuinapa (22.531758°, -105.450767°; datum WGS 84; elev. 10 masl) collected on 4 September 2017 by J. A. Loc-Barragan. (Fig. 4)

Paratypes— (3): An adult female (JALB-412, MZFC-HE 35628) (Fig. 2A) and juvenile male (JALB-411, MZFC-HE 35629) (Fig. 3) from Mexico: Sinaloa: Ejido La Concepción (La Concha), Municipio de Escuinapa (22.531758°N, - 105.450767°W; datum WGS 84; elev. 10 masl) (Fig. 4) collected on 15 October 2017 by J. LocBarragan, M. A. López-Luna and A. H. Escobedo-Galván; an adult female (UTEP 3908) (Fig. 2B) from Mexico: Nayarit: 11 km S of Acaponeta on Hwy. 15 (Fig. 4) collected on 23 August 1962 by R. G. Webb, D. W. Tinkle, W. Auffenberg, W. Auffenberg Jr., L. Irwin, W. Milstead and D. Patten.

Diagnosis —A small Kinosternon, the largest known specimen is a female (CL= 107.7 mm). This species is unique among Kinosternon of western Mexico, except K. vogti, of which it is a sister species, by possessing a very reduced and weakly kinetic plastron; a narrow bridge; and a proportionally wide carapace. We describe the diagnostic characteristics of Kinosternon cora with the species present on the Mexican Pacific versant (Table 2).

Kinosternon cora differs from K. chimalhuaca, Berry, Seidel and Iverson 1997, with which it was originally confused, by the following characters (character states of K. chimalhuaca in parentheses): A greater relative carapace width, average CW/CL ratio> 71% (<70%); a very small plastron; average PHW/CW <49% (> 49%); a narrow bridge, average BRL/CL <13% (>13%); and a relatively large axillary scute,> 60% of the size of the inguinal scute (<60% of the size of the inguinal scute).

Kinosternon cora differs from the broadly sympatric K. integrum LeConte 1854, by the following characters (character states of K. integrum in parentheses): A greater relative carapace width, average CW/CL ratio> 71% (<70%); a very small plastron, average PHW/CW <49% (> 55%); a long interfemoral scute seam, average FEL/HL> 40% (<40%); a narrow bridge, average BRL/CL <13% (>18%); and a relatively large axillary scute> 60% of the size of the inguinal scute (<35% of the size of the inguinal scute).

Kinosternon cora differs from the southern species, Kinosternon oaxacae Berry and Iverson 1980, by the following characters (character states of K. oaxacae in parentheses):A greater relative carapace width, average CW/CL ratio> 71% (<70%); a very small plastron, average PHW/CW <49% (> 53%); a long interfemoral scute seam, average FEL/HL> 40% (<40%); a narrow bridge, average BRL/CL <13% (>18%); a relatively large axillary scute,> 60% of the size of the inguinal scute (<40% of the size of the inguinal scute); and the first vertebral scute not in contact with M2 (first vertebral scute in contact with M2).

Kinosternon cora differs from the southernmost Mexican coastal species, Kinosternon scorpioides cruentatum (Duméril and Bibron 1851), by the following characters (character states of K. s. cruentatum in parentheses): A greater relative carapace width, average CW/CL ratio> 71% (<70%); a very small plastron, average PHW/CW <49% (> 60%); a long interfemoral scute seam, average FEL/HL> 40% (<20%); a narrow bridge, average BRL/CL <13% (>25%); a relatively large axillary scute,> 60% of the size of the inguinal scute (<40% of the size of the inguinal scute.

Kinosternon cora differs from the northern Pacific coastal species, Kinosternon alamosae Berry and Legler 1980, by the following characters (character states of K. alamosae in parentheses): A greater relative carapace width, average CW/CL ratio> 71% (<70%); a very small plastron, average PHW/CW <49% (> 70%); a long interfemoral scute seam, average FEL/HL> 40% (<35%); a narrow bridge, average BRL/CL <13% (>30%); and axillary and inguinal scutes in broad contact, separating the abdominal and marginal scutes (Axillary and inguinal scutes never in contact, abdominal and marginals in contact).

Kinosternon cora differs from the northernmost Mexican coastal species Kinosternon stejnegeri Hartweg 1938 (formerly K. arizonense Gilmore 1923 ), by the following characters (character states of K. stejnegeri): A very small plastron, average PHW/CW <49% (> 70%); a long interfemoral scute seam, average FEL/HL> 40% (<35%); a narrow bridge, average BRL/CL <13% (>25%); a relatively broad axillary scute, less than twice as long as wide (narrow axillary scute, three times longer than wide)

Kinosternon cora is a member of the K. hirtipes / integrum group. The subspecies of K. hirtipes (Wagler 1830), closest geographically to Kinosternon cora is K. h. chapalaense Iverson 1981. Kinosternon cora differs from K. h. chapalaense, by the following characters (character states of K. h. chapalaense in parentheses): A greater relative plastron width, average AHW/CL ratio> 40% (<35%); a very small plastron, average PHW/CW <49% (> 50%); a long interfemoral scute seam, average FEL/HL> 40% (<35%); and a narrow bridge, average BRL/CL <13% (>18%).

Kinosternon cora is the sister species of geographically proximate K. vogti (Fig. 4) with which it shares several characters that distinguish them both from the other species. However, Kinosternon cora differs from K. vogti by the following characters (character states of K. vogti in parentheses): a more robust body (body small); darker gray skin coloration (skin coloration pale grayish); a nuchal scale that is two to three times width than long (nuchal scale as wide as long; Figs. 5 A, B); marginal scale 11 half as high as marginal 10 (marginal 11 almost as high, or just a little shorter than marginal 10; Figs. 5 C, D); posterior plastral lobe not notched posteriorly (posterior plastral lobe notched; Figs. 5 E, F); plastron length smaller, average PL/CL ratio 80% (average PL/CL ratio 90%); bridge length shorter, average BRL/CL ratio 11% (average BRL/CL ratio 19%); rostral shield less conspicuous, V- shaped (rostral shield large and rounded); rostral shield the same color as the dorsal head coloration (rostral shield different color than coloration than head, bright yellow in males, pale yellowish in females Figs. 5 G, H); and males without yellow reticulations on head (males with small yellow reticulations on head).

CL Carapace length

CW Carapace width

CH Carapace height

PL Length of plastron

FL Length of forelobe

HL Length of plastral hindlobe

BRL Length of bony bridge

PS1 Length of plastral scute 1 (midline)

PS2 Length of plastral scute 6 (midline)

AIC Axillary-inguinal contact

M2C Contact between second marginal scute and first vertebral

*With the exception of K. cora and K. vogti, the data were compiled from Berry & Berry (1984), Berry & Iverson (1980), Berry & Legler (1980), Berry et al. (1997), Hulse (1976), Iverson (1981), and Legler &Vogt (2013).

Description of holotype — An adult female (JALB-391, MZFC - HE 35627), road-killed, with the carapace broken along the lateral plane, involving the costal scutes 2 and 4 on the right side, and costal scutes 2 and 3 on the left side. The marginal shields 5, 6, 7 on the right side, and 5 on the left side are fractured. The right abdominal is fractured in the region adjacent to the bridge. Although the fractures cracked the carapace and part of the plastron, the seam and proportions of the scutes remain in good condition. Characteristics and measurements are as follows: CL= 99.0 mm; CW= 89.4 mm; CH = 36.6 mm; HW= 27.0 mm; HL= 28.3 mm; AHW= 47.8 mm; LPH= 14.9 mm; FL= 30.0 mm; PHW= 36.0 mm; carapace relatively compressed and wide (CW/CL= 90 %); unicarinate with longitudinal keel slightly evident; growth rings evident on plastral and carapacial scutes; scutes imbricate; V1 very narrow, not in contact with M2; M1-9 aligned; M10 twice as high as M9 and M11; M11 slightly shorter than M9; V1, V2 and V3 longer than wide (22 x 17 mm, 23.3 x 20 mm, 23.9 x 20 mm), V4 as long as wide (21.3 x 22 mm), and V5 wider than long (12.4 x 23.1 mm). Plastron small (PL/CL= 80%), flat, with two kinetic hinges; anterior hinge straight and freely movable; posterior hinge flat anteriorly and not movable; posterior plastral lobe entire, not notched; axillary and inguinal scutes very wide and in full contact; axillary extends from middle M5 to middle M6; inguinal scute extending from middle M6 to posterior M7. Plastral formula 4>6>2>5>1>3. Head relatively wide (HW/CL= 27%), rostral shield large, furcate v-shaped, dark grayish; maxillary sheath hooked. Diameter of the tympanic membrane as large as the eye socket. One pair of small chin barbels elongated and conspicuous. Dorsal and lateral surfaces of the neck smooth. Tongue papillose. Jaw sheaths yellowish, streaked with dark brown. Manus and pes muscled and fully webbed; digital claws well developed. Keratinized patches on the posterior thigh and crus (clasping organs) poorly developed in the only known juvenile male; presumed to be well-developed in adult males. Falciform scales on antebrachium and heel typically kinosternine, keratinized. Tail very short, protruding slightly from the marginal shields and with a very small “claw” on the tip; with 4 dorsolateral longitudinal rows of poorly developed papillae.

Color of holotype in preservative: Coloration of carapace dark brown-olive with the edge of scutes black. Color of plastron orange with annuli proximal to midventral line dark brown; edges of the plastral scutes dark brown. Head grayish, with a reticulated pattern in buff or whitish, strongly reticulated laterally and ventrally. Overall, soft body parts with the same pattern. Figs. 1 and 6A show the holotype in preservative.

Variation — Including the holotype and three paratypes. The first measure corresponds to the average of three adult females, and the second measure to the only juvenile male collected; CL = 92.1–107.7 mm (µ=99.6 ± 7.6 mm), 75 mm; CW = 63.7–89.4 mm (µ=68.8 ± 13.5 mm), 58.6 mm; CH = 36.6–45.2 mm (µ=39.9 ± 4.6 mm), 30.4 mm; HW = 22.6–27.0 mm (µ=25.5 ± 2.5 mm), 20.0 mm; HL = 24.0–29.0 mm (µ=27.1.9 ± 2.7 mm), 23.3 mm; AHW = 37.0– 48.1 mm (µ=44.3 ± 6.3 mm), 34.2 mm; LPH = 10.0–15.0 mm (µ=13.3 ± 2.9 mm), 14.7 mm; FL= 30.0– 33.4 mm (µ=31.1 ± 2 mm), 25.3 mm; PHW = 30.0– 39.6 mm (µ=35.2 ± 4.8 mm), 27.0 mm; carapace compressed and wide (CW/CL = 70–90%, µ = 80%,), 70%; Scutellation and color of carapace are similar to holotype. Proportion PL /CL = 80–84% (µ = 81%), 86%. Plastral formula: 4>6>2>5>1>3 (50%), 4>2>6>5>1>2 (25%), 4>6>5>2>1>3 (25%). Relative head width (HW/CL) 25–27%; Rostral shield V-shaped on the supranasal region with a dark gray pattern color in all females, same shape in the male, but the color pattern of rostral shield dark, and slightly reticulated with yellow. Chin barbels and neck papillae similar to holotype. Characteristics of the females’ tail, similar to holotype; tail of juvenile male longer, reaching up to half of the M9, prehensile, the “claw” of the tail, inconspicuous to the eye, but hardened to the touch.

Color of paratypes in life: Coloration of carapace varies from olive-green to dark brown. The edges of scutes are invariably black. Color of plastron yellowish to bright orange, with dark brown outlines on the scutes, and with deep and dark interlaminar seams. Dorsal surfaces of head dark gray, with a pale yellow or whitish reticulations which become more dense laterally and ventrally. Reticulations become orange laterally on some individuals. An indistinct but dark-bordered and conspicuous pale yellow stripe on head, which runs from the posterior region of the beak, down to tympanic membrane. Jaw sheaths yellow-streaked or reticulated with dark brown. Lateral and ventral neck pale gray, but conspicuously reticulated (Fig. 6 A, B). Color of muscled manus, pes and tail gray-brownish above; thighs and forearm pale gray with reticulations.

Geographic distribution and habitat — Kinosternon cora inhabits low elevations from 10–30 m asl on the Pacific Coastal Plain adjacent to the foothills of the Sierra Madre Occidental. The predominant type of vegetation is tropical deciduous forest, with trees of 15–25 m in height. Along riparian areas tropical semi-deciduous forest is present, with Enterolobium sp., Ficus sp. and Taxodium mucronatum trees, which may reach a height of 30 m or more. Many trees and shrubs carry epiphytes and parasites. Eucalyptus crops have been planted in a large area near the type locality of Kinosternon cora (Fig. 7).

Etymology —The specific epithet is derived from the name “Cora”, the Native-Mexican ethnic group that is most widespread in Nayarit. The ethnic Cora population is concentrated in the municipalities of El Nayar, Acaponeta, Rosamorada and Ruiz, all of which are in Nayarit, the state where this new species was first discovered in 1962.

Additional observations —An adult male ( Fig. 8 A) was photographed from “just E of Rosamorada” on Rosa-morada–San Juan Bautista Hwy., Municipio de Rosamorada by J. Loc-Barragán in September of 2013. A juvenile female ( Fig. 8 B) was photographed at “a farm near Chilapa”, Municipio de Rosamorada (22.031930°, -105.227922°; datum WGS 84; elev. 30 masl) by Jorge Larios Luquín in October of 2019. Photographs of both individuals appear to be K. cora based on the diagnostic characteristics of the plastron and the carapace. We consider these sightings important as they extend the known distribution of this species.