Bioacoustics of Eleutherodactylus maculabialis

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 ).