Chiropterotriton chico, García-Castillo & Rovito & Wake & Parra-Olea, 2017

García-Castillo, Mirna G., Rovito, Sean M., Wake, David B. & Parra-Olea, Gabriela, 2017, A new terrestrial species of Chiropterotriton (Caudata: Plethodontidae) from central Mexico, Zootaxa 4363 (4), pp. 489-505 : 497-502

Chiropterotriton chico sp. nov.

El Chico Salamander

Salamandra de El Chico ( Figures 3A and 4A )

Chiropterotriton multidentata (part): Taylor, 1944.

Chiropterotriton cf multidentatus (part): Rabb, 1958; Darda, 1994. Chiropterotriton sp. 15: Parra-Olea, 2003; Rovito & Parra-Olea, 2015

Holotype. MVZ 118888, an adult male from El Chico National Park, Hidalgo, Mexico, 2950–3050 m, 20.184154º N, 98.734437º W (maximum error distance 5477 m). Collected 31 July 1972 by James Lynch and Lynne D. Houck.

Paratypes. Twenty-nine specimens, all from Hidalgo, Mexico. Fifteen males: MVZ 118752 , 118804 , 118811 , 118821 , 118827 , 118842 , 118869 , 118900 , 119053 , 119057 , 119078 , 119166 , 119212 , 119216 , El Chico National Park ; MVZ 138852, road to El Chico National Park, 1.0 km N (by road) junction Hwy. 105. Fourteen females: MVZ 114436, El Chico National Park, 4 km S (by road) Mineral del Chico; MVZ 118740, 118791, 118793, 118798, 118800, 118816, 118901, 118905, 119016, 119034, 119062, 119179, 119193, El Chico National Park.

Referred specimens. CAS 13112–13113; ENCB 139-142; IBH 23105; LACM 68955–69037, 69066–69071, 124057–124087, 168383–168388; MCZ A-25605–25606, A-93296 –93297; MVZ 46909, 97959, 98956–99022, 103938–103960, 106596–106655, 114292–114297, 114420–114435, 114437–114489, 118047–118739, 118741– 118751, 118753–118790, 118792, 118794–118797, 118799, 118801–118803, 118805–118810, 118812–118815, 118817–118820, 118822–118826, 118828–118841, 118843–118868, 118870–118887, 118889–118899, 118902– 118904, 118906–119015, 119017–119033, 119035–119052, 119054–119056, 119058–119061, 119063–119077, 119079–119165, 119167–119178, 119180–119192, 119194–119211, 119213–119215, 119217–119220, 128972– 128977, 138853–138866, 143864–143893, 163620–163629, 172142–172147, 183645–183654, 195833–195835, 199175–199190, 200679, 219569–219571; UCM 41242–41252; UMMZ 151186 – 151192; USNM 116324– 116338, 134284–134286, 201055 - 201057, 204910–204913, 249001-249004; UTEP 657–658.

Diagnosis. A plethodontid salamander assigned to Chiropterotriton because of small size, presence of sublingual fold, and distinctive shape of the digits of the hand and foot (with a relatively long outer digit; Wake & Elias 1983), as well as on the basis of analyses of mtDNA sequence data. Phylogenetically most closely related to C. terrestris , also from the state of Hidalgo. Morphological differences between C. chico and its sister taxon C. terrestris are much larger size (mean SVL 38.4 in males and 39.3 in females of C. chico vs. 24.1 in males, 23.0 in females of C. terrestris ), relatively longer tail (mean TL/SVL 1.18 in males and 1.12 in females of C. chico vs. 1.05 in males and 0.97 in females of C. terrestris ), longer limbs (mean LI 0.6 costal folds in males and 2.1 in females of C. chico vs. 1.9 in males, 2.6 in females of C. terrestris ), longer head (mean HL 8.8 in males and 8.7 in females of C. chico vs. 5.7 in males and 5.2 in females of C. terrestris ), broader head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 3.5 in males and 3.3 in females of C. terrestris ), broader feet (mean FW 4.1 in males and 4.2 in females of C. chico vs. 1.9 in males and 1.6 in females of C. terrestris ), more maxillary and premaxillary teeth (mean MT+PMT 42.3 for males and 56.5 for females of C. chico vs. 21.2 for males and 38.2 for females of C. terrestris ), and more vomerine teeth (mean VT 13.6 in males and 15.6 in females of C. chico vs. 8.8 in males and 9.9 in females of C. terrestris ).

Chiropterotriton chico differs from C. arboreus in the following characteristics: larger size (mean SVL 38.4 in males, 39.3 in females of C. chico vs. 33.4 in males, 32.2 in females of C. arboreus ), relatively longer tail (mean TL/SVL 1.18 in males, and 1.12 in females of C. chico vs. 0.83 in males and 0.87 in females of C. arboreus ), shorter limbs (mean LI 0.6 in males, 2.1 in females of C. chico vs. 0.2 in males, 1.0 in females of C. arboreus ), longer head (mean HL 8.8 in males and 8.7 in females of C. chico vs. 7.9 in males and 7.5 in females of C. arboreus ), broader head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 5.0 in males and 4.8 in females of C. arboreus ), broader feet (mean FW 4.1 in males and 4.2 in females of C. chico vs. 3.4 in males and 3.5 in females of C. arboreus ), more maxillary and premaxillary teeth (mean MT+PMT 42.3 for males and 56.5 for females of C. chico vs. 26.5 for males and 33.4 for females of C. arboreus ) and more vomerine teeth (mean VT 13.6 in males and 15.6 in females of C. chico vs. 11.2 in males, and 12.4 in females of C. arboreus ).

Chiropterotriton chico differs from C. chondrostega in the following characteristics: larger size (mean SVL 38.4 in males, 39.3 in females of C. chico vs. 23.0 in males, 25.4 in females of C. chondrostega ), longer tail (mean TL/SVL 1.18 in males and 1.12 in females of C. chico vs. 0.92 in males and 1.07 in females of C. chondrostega ), longer limbs (mean LI 0.6 in males and 2.1 in females of C. chico vs. 2.0 in males, 3.0 in females of C. chondrostega ), longer head (mean HL 8.8 in males and 8.7 in females C. chico vs. 5.5 in males and 5.7 in females of C. chondrostega ), broader head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 3.4 in males and 3.7 in females of C. chondrostega ), broader feet (mean FW 4.1 in males and 4.2 in females of C. chico vs. 1.8 in males and females of C. chondrostega ), more maxillary teeth (mean MT+PMT 42.3 for males and 56.5 for females of C. chico vs. 22.5 for males and 40.9 for females of C. chondrostega ), and more vomerine teeth (mean VT 13.6 in males and 15.6 in females of C. chico vs. 8 in males and 10 in females of C. chondrostega ).

Chiropterotriton chico differs from C. mosaueri by its relatively shorter tail (mean TL/SVL 1.18 in males and 1.12 in females of C. chico vs. 1.31 in males and 1.39 in a female of C. mosaueri ), narrower head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 6.8 in males and 7.0 in a female of C. mosaueri ), fewer maxillary and premaxillary teeth (mean MT+PMT 42.3 for males and 56.5 for females of C. chico vs. mean MT 69.0 for males and 70 for a female of C. mosaueri ), and fewer vomerine teeth (mean VT 13.6 in males and 15.6 in females of C. chico vs. 28 in males and 20 in a female of C. mosaueri ) ( Woodall 1941; Rabb 1958; Rovito & Parra-Olea 2015).

Chiropterotriton chico differs from C. multidentatus , by its larger size (mean SVL 38.4 in males, 39.3 in females of C. chico vs. 33.6 in males, 34.0 in females of C. multidentatus ), slightly longer tail (mean TL/SVL 1.18 in males, and 1.12 in females of C. chico vs. 1.13 in males and 1.03 in females of C. multidentatus ), shorter limbs (mean LI 0.6 in males, 2.1 in females of C. chico vs. 0.1 in males, 1.0 in females of C. multidentatus ), longer head (mean HL 8.8 in males and 8.7 in females C. chico vs. 7.4 in both males and females of C. multidentatus ), broader head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 4.9 in males and 5.1 in females of C. multidentatus ), broader feet (mean FW 4.1 in males and 4.2 in females of C. chico vs. 3.6 in males and 3.5 in females of C. multidentatus ), and fewer maxillary and premaxillary teeth (mean MT+PMT 26.0 for males and 36.0 for females of C. chico vs. 40.0 for males and 49.0 for females of C. multidentatus ).

Chiropterotriton chico differs from C. cieloensis by its larger size (mean SVL 38.4 in males, 39.3 in females of C. chico vs. 32.6 in males, 31.1 in females of C. cieloensis ), shorter limbs (mean LI 0.6 in males, 2.1 in females of C. chico vs. - 0.2 in males, 0.1 in females of C. cieloensis ), longer head (mean HL 8.8 in males and 8.7 in females of C. chico vs. 7.1 in males and 6.9 in females of C. cieloensis ), broader head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 4.8 in males and 4.9 in females of C. cieloensis ), broader feet (mean FW 4.1 in males and 4.2 in females of C. chico vs. 3.2 in males and 3.1 in females of C. cieloensis ); more maxillary and premaxillary teeth (mean MT+PMT 42.3 for males and 56.5 for females of C. chico vs. 31.0 for males and 47.0 for females of C. cieloensis ), and more vomerine teeth (mean VT 13.6 in males and 15.6 in females of C. chico vs. 11.5 in males, and 12.8 in females of C. cieloensis ).

Chiropterotriton chico differs from C. infernalis by its larger size (mean SVL 38.4 in males, 39.3 in females of C. chico vs. 36.4 in males, 29.7 in a female of C. infernalis ), shorter limbs (mean LI 0.6 in males, 2.1 in females of C. chico vs. - 0.7 in males, - 0.5 in a female of C. infernalis ), less extensive feet webbing (moderate webbing that extends just onto penultimate phalanx in C. chico vs. extensive foot webbing onto penultimate phalange in C. infernalis ; Fig. 3A, I ), and slightly longer head (mean HL 8.8 in males and 8.7 in females C. chico vs. 8.2 in males and 6.2 in a female of C. infernalis ).

Chiropterotriton chico differs from C. cracens in body size (mean SVL 38.4 in males, 39.3 in females of C. chico vs. 25.7 in males, 27.4 in females of C. cracens ) and by having shorter limbs in males (mean LI 0.6 of C. chico vs. 1.8 of C. cracens ), a longer head (mean HL 8.8 in males and 8.7 in females C. chico vs. 5.5 in males and 5.8 in females of C. cracens ), broader head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 3.8 in males and 4.1 in females of C. cracens ), broader feet (mean FW 4.1 in males and 4.2 in females of C. chico vs. 2.2 in males and 2.5 in females of C. cracens ), and more maxillary and premaxillary teeth (mean MT+PMT 42.3 for males and 56.5 for females of C. chico vs. 36.8 for males and 49.5 for females of C. cracens ).

Chiropterotriton chico differs from its sympatric species C. dimidiatus by its larger size (mean SVL 38.4 in males, 39.3 in females of C. chico vs. 24.6 in males, 25.8 in females of C. dimidiatus ), relatively longer tail (mean TL/SVL 1.18 in males, and 1.12 in females vs. 0.89 in males, and 0.86 in females of C. dimidiatus ), longer limbs (mean LI 0.6 in males, 2.1 in females of C. chico vs. 3.8 in males, 4.9 in females of C. dimidiatus ), longer head (mean HL 8.8 in males and 8.7 in females of C. chico vs. 5.2 in males and 5.0 in females of C. dimidiatus ), broader head (mean HW 5.6 in males and 5.7 in females of C. chico vs. 3.4 in males and 3.5 in females of C. dimidiatus ), broader feet (mean FW 4.1 in males and 4.2 in females of C. chico vs. 1.7 in both males and females of C. dimidiatus ), more numerous maxillary and premaxillary teeth (mean MT+PMT 42.3 for males and 56.5 for females of C. chico vs. 9.4 for males and 34.4 for females of C. dimidiatus ), and vomerine teeth (mean VT 13.6 in males and 15.6 in females of C. chico vs. 5.6 in males, and 8.3 in females of C. dimidiatus ). Moreover, C. chico is easily distinguished for relative narrow nostril size (mean NW/HW 0.01 in both males and females of C. chico vs. 0.07 in both males and females of C. dimidiatus ), this character is evident even in very small individuals.

Chiropterotriton chico differs from most of the remaining species of the genus, in having relatively large size (mean SVL 38.4 males, 39.3 females). Exceptions are the much stouter and somewhat larger C. priscus Rabb (mean SVL 38.5 males, 41.8 females; Rovito & Parra-Olea 2015) and C. magnipes Rabb (range SVL 40– 53 males, 51– 60 females; Campbell et al. 2014). C. chico has more maxillary teeth than most other species of this genus (mean MT+PMT 42.3 for males and 56.5 for females), except for C. multidentatus (mean MT+PMT 40.0 for males and 47.8 for females; Rovito & Parra-Olea 2015) and C. infernalis (mean MT+PMT 42.3 for males and 56.5 for females; Rovito & Parra-Olea 2015) which have similar numbers of teeth, and C. magnipes (males average 79; Campbell et al. 2014) and C. mosaueri (range in males 56–69; Campbell et al. 2014), which have more maxillary teeth.

Description. This is a medium sized species of Chiropterotriton ; mean SVL 38.4 in fifteen adult males (range 36.2–42.6) and 39.3 in fifteen adult females (range 35.9–44.3). The head is relatively narrow and moderately long ( Fig. 3 ), HW averages 14% of SVL in both males and females (range 11–16). In males, the snout is broad and truncated. Jaw muscles are pronounced and visible as a bulging mass immediately behind the eyes. Eyes are moderately protuberant and extend laterally beyond the jaw margin in ventral view. There are a moderate number of maxillary and premaxillary teeth in males (mean MT+PMT 42.3, range 32–52) and more in females (mean MT+PMT 56.5, range 48–67). There are few vomerine teeth in males (mean 13.6, range 10–19) and females (mean 15.6, range 13–19). The tail is long; mean TL equals 1.18 of SVL in males (range 0.96–1.27) and 1.12 of SVL in females (range 0.98–1.24). Limbs are moderate and slender; (FLL+ HLL)/SVL average 0.48 in males (range 0.82– 1.11) and 0.98 in females (range 0.87–1.13). Adpressed limbs approach closely on males (mean LI 0.6, range 0–1) but they are separated by as many as two costal folds in females (mean 2.1, range 1.5–3.0). Digits are slender and expanded distally, with distinct subterminal pads and moderate webbing at the base. All digits are discrete, however the first barely extends beyond the margins of the webbing and it extends just onto penultimate phalanx of the longest toe ( Fig. 3 ). The outermost toes are particularly well developed. The smallest male with a mental gland is 36.2 SVL. Parotoid glands not evident. Prominent oval-shaped mental gland is present in all adult males. Vomerine teeth arranged in a well-defined line extending to outer margin of choanae. Digits in order of increasing length: hand I-IV-II-III, foot I-V-II-IV-III. Phalangeal formulae: hand 1-2-3-2, foot 1-2-3-3-2.

Coloration of the holotype in alcohol. Holotype uniform dark tannish brown dorsally becoming paler laterally and very pale cream ventrally. There is a central reddish brown stripe flanked by yellow lines. The stripe extends from to the postocular region, where it has yellow spots, to the base of the tail where it also leaves two yellow spots. The entire tail is a slightly darker brown than the body. Limbs are lighter in color than dorsum but still dark brown. Snout is mottled with dark and light brown. Dorsal surface of hands and feet only slightly lighter than body.

Measurements of the holotype (in mm), tooth counts and limb interval. — SVL 42.2, TL 46.1, AX 22.4, SW 5.2, HL 9.8, HW 6.3, HD 3.1, projection of snout beyond mandible 1.4, anterior rim of orbit to snout 2.7, interorbital distance 2.6, eyelid length 2.2, eyelid width 1.4, horizontal orbit diameter 2.7, NL 0.14, NW 0.06, FLL 8.5, HLL 10.7, snout to forelimb 12.8, snout to anterior angle of vent 42.1, tail width at base 3.1, tail depth at base 3.2, FW 4.0, length of fifth toe 0.7, length of third (longest) toe 1.2. MT+PMT 60, VT 6-7 (right-left sides). Adpressed limbs separated by two costal folds.

Habitat and range. This species is only known from Parque Nacional El Chico in Hidalgo, Mexico at an elevation between 2400 and 3050 m, in pine-oak forest. It is unlikely to occur more widely, because surrounding areas have been extensively surveyed.

Etymology. The species name chico is in reference to the national park where the species occurs. Parque Nacional El Chico in Hidalgo, Mexico has been a protected area since 1922. The species name is used as an invariable noun in apposition to the generic name.

Remarks. This species was previously considered as conspecific with C. multidentatus and occurs in sympatry with C. dimidiatus and Aquiloeurycea cephalica . Likewise, Isthmura bellii has been collected very near sites where C. chico was once common (MVZ 118953, 118954, 128978), but it is unknown if the two species occur in syntopy.

Figures

FIGURE 3. Head, hand and foot morphology of Chiropterotriton specimens from Hidalgo A) C. chico, holotype MVZ 118888, B)C.arboreus, MVZ 172159, C)C.chondrostega MVZ 106660, D) C.dimidiatus MVZ 178671, E) C.mosaueri IBH 28179, F) C. terrestris, MVZ 106700, and Tamaulipas and San Luis Potosí G) C. cieloensis, holotype IBH 29561, H) C. cracens MVZ 129005, I) C. infernalis, holotype MVZ 269665, J) C. multidentatus MVZ 163908. Scale bar corresponds to 2 mm.

FIGURE 4. Photos in life of Chiropterotriton. A) Chiropterotriton chico, DBW (Jan 1974) B) C. arboreus, DBW, C) C. chondrostega, SMR (IBH 28195), D) C.dimidiatus, DBW 1342-45, E) C.mosaueri SMR (IBH 28179), F)C.terrestris, DBW, G) C. cieloensis, SMR holotype (IBH 29561), H) C. cracens, SMR (IBH 28192), I) C. infernalis, SMR holotype (MVZ 269665), J) C. multidentatus SMR (IBH 29571).