Syrrhophus modestus Taylor, 1942:304-06, pl. 29 [Holotype.—FMNH 100048 (formerly EHT-HMS 3756), from Hacienda Paso del Río, Colima, México; collected on July 8, 1935, by Hobart M. Smith]. Smith and Taylor, 1948:49-50.
Syrrhophus modestus modestus: Duellman, 1958:2-5, 7, 14, pl. 1, fig. 1. Gorham, 1966:166.
Diagnosis.—Small frogs, males 15.8-20.1 mm. snout-vent length, single female 18.5 mm.; vocal slits present in males; finger tips widely expanded; first finger shorter than second; inner metatarsal tubercle about three times size of outer; skin of dorsum shagreened, that of venter smooth; tympanum concealed; pale cream in preservative with dark brown spots; limbs banded; bands on forearm and thigh poorly developed or absent; interorbital bar absent.
Remarks.—The tympanum is concealed in S. modestus, S. nivocolimae, S. pallidus, S. teretistes, and to a lesser degree in S. interorbitalis. However, if the specimen is permitted to dry slightly, the annulus tympanicus becomes visible through the skin and a tympanum/eye ratio can be computed.
One of the few cases of sympatry within the genus Syrrhophus involves this species; modestus and nivocolimae are known to be sympatric at one locality in southwestern Jalisco, México.
Duellman (1958) used the trinomial for this population and named a new subspecies, pallidus, from Nayarit. I consider pallidus to be specifically distinct from modestus because there is no evidence of genetic exchange, and there is no overlap in the distinguishing morphological features. I do consider the two populations to be closely related but feel the inter-relationships between modestus, pallidus, nivocolimae, and teretistes are more complex than would be indicated by the use of trinomials. The sympatric occurrence of modestus and nivocolimae is significant; morphologically, they might otherwise be regarded as subspecies. Although allopatric, similar arguments could be advanced for the morphologically similar pallidus and teretistes. The four are here afforded species rank since morphological similarity and allopatry are not sufficient grounds for the assumption of genetic exchange.
Fig. 19: Syrrhophus modestus [left, UMMZ 115447 (WED 11155)] and S. pallidus (right, UMMZ 115453). ×2.2.
Etymology.—Latin, meaning unassuming, modest, in reference to the small size of the species.