Eleutherodactylus maculabialis, Grünwald & Reyes-Velasco & Franz-Chávez & Morales-Flores & Ahumada-Carrillo & Rodriguez & Jones, 2021

Grünwald, Christoph I., Reyes-Velasco, Jacobo, Franz-Chávez, Héctor, Morales-Flores, Karen I., Ahumada-Carrillo, Ivan T., Rodriguez, Christopher M. & Jones, Jason M., 2021, Two new species of Eleutherodactylus (Anura: Eleutherodactylidae) from Southern Mexico, with comments on the taxonomy of related species and their advertisement calls, Amphibian & Reptile Conservation (e 272) 15 (1), pp. 1-35 : 4-9

Eleutherodactylus maculabialis sp. nov.

Spot-lipped Trilling Frog, Rana trinadora de labios manchados.

Figs. 1–2, 7A.

urn:lsid:zoobank.org:act:55184A71-4558-4E49-B379-73A8641939C9

Holotype. MZFC 33312 ( CIG 00921 ). Adult male ( Fig. 1), 11.4 km S of Puerto de Gallo, Municipality of Atoyac

de Álvarez (17.4672, -100.1916, datum = WGS84 ; 1,980 m asl), Guerrero, Mexico ( Fig. 8A), collected on 15 July 2016 by Christoph I. Grünwald and Héctor Franz-Chávez .

Paratypes (n = 13; Fig. 2). MZFC 33307–311 , 33313– 314 ( CIG 00916–920 ; 00922–923), seven adult males, collected at same locality and on same date as holotype ; MZFC 33315–316 ( CIG 00940–941 ), two adult males, 1.0 km S of bridge between Nueva Delhi and El Paraíso, Municipality of Atoyac de Álvarez (17.4150, -100.1924 datum = WGS84 ; 1,320 m asl), Guerrero, Mexico, collected on 15 July 2016 by Christoph Grünwald and Héctor Franz-Chávez ; MZFC 33317–319 ( CIG 00945– 00947 ), two adult males, Yerba Santa , Municipality of General Heliodoro Castillo (17.5202, -99.9639, 2,003 m asl; datum = WGS84 ), Guerrero, Mexico collected on 16 July 2016 by Christoph Grünwald and Héctor Franz-Chávez ; MZFC 33321 ( CIG 00949 ), one adult male, 8.5 km N of Yerba Santa on road to Carrizal de Bravo , Municipality of General Heliodoro Castillo (17.5269, -99.9371, 1,880 m asl; datum = WGS84 ), Guerrero, Mexico, collected on 16 July 2016 by Christoph Grünwald and Héctor Franz-Chávez .

Diagnosis. Based on the phylogenetic analysis, this is a member of the genus Eleutherodactylus , subgenus Syrrhophus , as defined by Hedges et al. (2008). It is in the Eleutherodactylus (Syrrhophus) nitidus species series and the Eleutherodactylus (Syrrhophus) nitidus species group as defined by Grünwald et al. (2018) based on the condition of the tympanic annuli, ventral epidermis, and visceral peritoneum. A small frog, adult males measure 17.9–24.7 mm SVL; vocal slits are present in males, readily visible under partially translucent ventral epidermis; digital tips are expanded, 1.5–2.1 times the width of the narrowest part the finger on the third and fourth fingers; fingers moderately long, finger lengths are I-II-IV-III with third finger length ranging from 17– 19% of SVL; compact lumbar gland above the inguinal region present, indistinct, barely visible in live specimen; ventral epidermis is partially translucent and visceral peritoneum is clear, not white, thus abdominal vein is not clearly visible against a white background on the venter of live specimens, and viscera are partially visible through translucent dark gray ventral epidermis; limbs moderate, TL/SVL ratio is 0.44–0.50, FeL/SVL ratio is 0.41–0.47 and TotFL/ SVL ratio is 0.66–0.73; snout relatively short, END/ SVL ratio is 0.10–0.12; tympanum small, indistinct and round, tympanic annuli not visible in live specimen; TW/ED ratio is 0.25–0.29. The dorsal, lateral, and ventral skin is smooth or slightly shagreen. Dorsal coloration variable, orange, tan, or brown, with darker brown marbling; loreal region dark brown, with conspicuous large white or orange spots present on upper labial region, and 1–3 orange spots on lower loreal region and upper portion of upper labia; pale interorbital bar present, orange or tan, same color as palest dorsal coloration; indistinct transverse bands present on legs; upper arms same coloration and pattern as forearms; no pale mid-dorsal stripe; upper flanks same color as dorsum, lower flanks lavender or gray with white spots and marbling; venter gray to dark gray with sparse white spots or marbling present. Red, reddish, or orange inguinal flash colors sometimes present on thighs and groin; however, when present these colors are not more vivid than the coloration of the light interorbital bar and the characteristic colored spots on the upper lip. The mating call of adult males is a short trill (see below; Fig. 3).

Comparisons. Eleutherodactylus maculabialis can be distinguished from all species in the Eleutherodactylus (Syrrhophus) longipes species series by: possessing a small, indistinct tympanum with no tympanic annulus visible and with a diameter less than 30% of diameter of the eye; by possessing a ventral epidermis which is not clear, and combined with a visceral peritoneum which is not white, an abdominal vein on the venter which is not clearly evident against a white background in life; and by possessing a distinct, raised lumbar gland above the inguinal region.

Eleutherodactylus maculabialis can be distinguished from species of the Eleutherodactylus (Syrrhophus) modestus species group by the combination of possessing a compact, protruding lumbar gland above the inguinal region, digital tips which are expanded more than 1.5 times the width of the narrowest part the finger on the third and fourth fingers, and the presence of an interorbital bar.

Within its own species group, E. maculabialis can be distinguished from most species by possessing a compact inguinal gland that is indistinct but visible in live specimens. This character may or may not be visible in preserved specimens depending on how they were preserved. This species differs from E. pipilans , E. erythrochomus , and E. nebulosus , which lack a visible compact lumbar gland altogether. All other known species in the E. (Syrrhophus) nitidus species group have readily visible compact lumbar glands above the inguinal region. Eleutherodactylus maculabialis can be further distinguished from E. pipilans and E. nebulosus by possessing digital tips which are expanded more than 1.5 times the width of the narrowest part of the finger, and from E. erythrochomus by possessing digital tips which are more than 1.5 times but less than 3.0 times the width of the narrowest part of the finger. It may be distinguished from E. nitidus , E. petersi , and E. orarius by the combination of smoother skin, longer limbs, and tips of digits which are expanded more than 1.5 times the narrowest part of the finger on the third and fourth fingers. It is distinguished from E. albolabris by the following characters (characters of E. albolabris in parentheses): smaller size, 17.9–24.7 mm (23.0– 26.8 mm), venter which is partially translucent and partially white with black markings (entire venter white with black markings), pale longitudinal blotch absent in mid-dorsal area (pale mid-dorsal blotch usually present in mid-dorsal area), smaller tympanum with TW/ED 0.25–0.28 (larger tympanum with TW/ ED 0.27–0.32). Eleutherodactylus maculabialis may be distinguished from E. dilatus by the following characters (characters of E. dilatus in parentheses): smooth dorsal and ventral skin (rugose), dark gray ventral coloration with white spots (white ventral coloration with dark gray marbling), conspicuous white or orange spots on labial region (dark labial region, sometimes with white or pale yellow speckling), flash color absent, or when present not brighter than the pale coloration on dorsum and head (bright yellow flash coloration in inguinal region). Eleutherodactylus maculabialis may be distinguished from E. maurus by the following characters (characters of E. maurus in parentheses): presence of pale interorbital bar same color as snout (no pale interorbital bar), dark gray ventral coloration with white spots (white ventral coloration with dark gray marbling), conspicuous white or orange spots on labial region (dark labial region, sometimes with white or pale yellow speckling), smooth dorsal and ventral skin (rugose or slightly rugose dorsal and ventral skin), no pale mid-dorsal stripe present and upper arms same color as rest of limbs (thick, pale brown mid-dorsal strip usually present and upper arms pale ground coloration, unmarked and lighter than other limbs). Eleutherodactylus maculabialis is most similar to E. syristes . Both species share smooth dorsal and ventral skin, distinct compact lumbar glands above the inguinal region which are variably marked, a variable dorsal coloration of orange, brown, or tan with darker marbling, and similar red, reddish, or orange flash colorations. Eleutherodactylus maculabialis may be distinguished from E. syristes by the following characters (characters of E. syristes in parentheses): digital tips expanded more than 1.5 times the width of the narrowest part the finger on the third and fourth fingers (digital tips which are expanded 1.1–1.5 times the width of the narrowest part the finger on the third and fourth fingers), ventral coloration dark, with pale orange or white spots (ventral coloration white, with dark gray or black marbling and reticulations), conspicuous white or orange spots on labial region (labial region dark, occasionally with light gray or white speckling). Furthermore, E. maculabialis differs from all species in its species group by its advertisement call, which is a short trill. The only other species in the species group which has an advertisement call that is a trill is E. syristes , but the call of that species is much more drawn-out (see below, Fig. 11A–B).

Description of the holotype. Male, relatively small (23.5 mm SVL); head longer (7.8 mm) than wide (6.9 mm), head slightly wider than body; snout subovoid from a dorsal view and rounded from a lateral profile;

tympanum indistinct, rounded with no supra-tympanic fold present; tympanum small, circular, greatest width of tympanum 0.7 mm; greatest diameter of eye 2.7 mm; tympanum width to eye diameter 0.27; eyelid width 1.5 mm, approximately 32% of the IOD, first finger shorter than second finger; finger lengths from shortest to longest I-II-IV-III with two and three equal; digital pads on fingers two, three, and four expanded, 1.9 times the narrowest point of the digit on fingers three and four; expanded finger pads slightly rounded, three palmar tubercles; inner palmar tubercle about 70% as large as middle palmar tubercle, outer palmar tubercle about 45% the size of middle palmar tubercle ( Fig. 6A); toe lengths from shortest to longest I-V-II-III-IV, TL2 and TL5 very similar; outer metatarsal conical with a round base, moderate, approximately 66% of inner metatarsal tubercle; inner metatarsal tubercle spherical shape with oval base, large, approximately 0.9 mm in length. Dorsal skin smooth, lateral skin slightly shagreened, ventral skin smooth to slightly areolate. Skin was smooth in life. Vocal slits present.

In life the holotype had a reddish-tan dorsal coloration on the back ( Fig. 1A–C), with darker brown mottling that was increasingly dense towards the mid-dorsal area. The pale orange was present on flanks, interorbital bar and spots on labial region. The flanks were reddish-tan with indistinct darker brown mottling and small white spots. The hind legs and arms were reddish-tan with irregular brown transverse bars. Bright reddish-orange flash colors on groin or thighs. Ventral coloration was gray with white and orange spots on throat and upper chest.

Coloration in preservative is light brown dorsum, with darker brown markings and a pale tan interorbital bar. The dorsal surfaces of the legs are light brown and the groin and posterior surfaces of the thighs are brown. The venter is white, with light brown on throat ( Fig. 1D–E).

Measurements of the holotype (in mm). IND 2.5, IOD 4.8, END 2.5, ETD 0.9, UpL 6.3, FoL 7.5, HaL 5.5, F1L 1.8, F1 PW 0.5, F1 W 0.4, F2L 2.4, F2 PW 0.7, F2 W 0.4, F3L 3.9, F3 PW 0.9, F3 W 0.5, F4L 2.4, F4 PW 0.8, F4 W 0.4, IPTL 0.7, MPTL 1.0, OPTL 0.4, FeL 10.5, TL 11.5, TaL 5.9, FL 10.2, T 2L 3.5, T 2 PW 0.8, T 2 W 0.5, T 3L 4.6, T 3 PW 0.8, T 3 W 0.5, T 4L 7.2, T 4 PW 0.9, T 4 W 0.5, T 5L 3.1, T 5 PW 0.6, T 5 W 0.4, IMTL 0.9, OMTL 0.6, FeL/SVL 45%, TL/SVL 49%, Ha/SVL 23%, FL/SVL 43%, HL/SVL 33%, HW/SVL 29%.

Variation. SVL from 17.9–24.7 mm (21.65 + 1.77). Expanded finger pads vary from 1.5–2.1 times the narrowest part of the digit on the third and fourth fingers, with average of 1.7 + 0.21 on the third finger and average of 1.73 + 0.21 on the fourth finger. Dorsal ground coloration ranged from different shades of tan, reddish, or brown, always with darker brown coloration on the dorsum. Different degrees of dark mottling are present on the dorsal surfaces. Venter always gray, but with varying amounts of white spots. Characteristic bright orange spots on upper part of upper labial and lower part of loreal region present in most individuals ( MZFC 33307–314); however, these spots may be faded or white in individuals from lower elevations ( MZFC 33315–19, 33321), and one specimen ( MZFC 33316) has only one pale spot on the right side, and none on the left. In some individuals, orange coloration may be lacking on the lip ( MZFC 33315–19, 33321), in these individuals it is lacking everywhere, including the inguinal region and on the interorbital bar. Morphological variation is presented in Table 1.

Distribution and ecology. This species is known from two municipalities in the Sierra Madre del Sur of central Guerrero ( Fig. 7A). It has been collected in tropical evergreen forest, cloud forest, oak woodland, pine-oak forest, and riparian vegetation between 900–2,100 m asl. All specimens were collected from low-growing vegetation or rocks along road cuts while calling in the month of July. This species has been collected in sympatry with E. albolabris and E. nitidus .

Etymology. From the combination of the Latin words maculatus and labialis, meaning spotted-lip, named for the conspicuous bright colored spots on the upper lip and above the rictus, present in varying degrees, which along with the advertisement call help to readily distinguish this species in the field.

Referred specimens. CIG 01484–01485 , 01501 , three adult males collected at the type locality on 29 June 2019 by Christoph I. Grünwald, Karen I. Morales-Flores, Janelle Morales-Flores; JAC 22216, one adult male, collected between Nueva Delhi and Puerto del Gallo, Municipality of Atoyac de Álvarez (17.4668, 100.198, 2,020 m asl, datum WGS84 ), Guerrero, Mexico on 15 June 2002 by Jonathan A. Campbell; JAC 25643–25646, four adult males, collected at Nueva Delhi , Municipality of Atoyac de Álvarez (17.4113, -100.1954, 1,239 m asl, datum WGS84 ), Guerrero, Mexico on 6 July 2004 by Jonathan A. Campbell .