Middle American Frogs of the Hyla microcephala Group Part 2

Table 2.--Variation in Color Pattern in Hyla microcephala underwoodi ========================================================================== Population | N | Shanks || Interorbital || Dorsolateral | | | || bar || stripe | | |-------------||----------------||--------------| | | Bars |Flecks|| Present| Absent|| Groin| Sacrum| -------------------------------------------------------------------------- Oaxaca: | 27 | 22 | 5 || 27 | 0 || 0 | 27 | Donaji-Sarabia | | | || | || | | | | | || | || | | Tabasco: | 55 | 46 | 9 || 55 | 0 || 0 | 55 | Teapa-Villahermosa| | | || | || | | | | | || | || | | Guatemala: | 51 | 51 | 0 || 51 | 0 || 17 | 34 | La Libertad | | | || | || | | | | | || | || | | Guatemala: | 32 | 32 | 0 || 32 | 0 || 0 | 32 | Finca Chama | | | || | || | | | | | || | || | | Guatemala: | 31 | 31 | 0 || 31 | 0 || 14 | 17 | Puerto Barrios | | | || | || | | | | | || | || | | Honduras: | 13 | 13 | 0 || 13 | 0 || 9 | 4 | Lago Yojoa | | | || | || | | | | | || | || | | Nicaragua: | 56 | 44 | 12 || 54 | 2 || 13 | 43 | La c.u.mplida | | | || | || | | | | | || | || | | Nicaragua: | 10 | 10 | 0 || 10 | 0 || 8 | 2 | Tipitapa | | | || | || | | | | | || | || | | Nicaragua: | 10 | 10 | 0 || 10 | 0 || 8 | 2 | Santo Thomas | | | || | || | | | | | || | || | | Costa Rica: | 12 | 0 | 12 || 6 | 6 || 7 | 5 | Tenorio-Tilaran | | | || | || | | | | | || | || | | Costa Rica: | 38 | 21[A]| 15 || 34 | 4 || 25 | 13 | Las Canas-Liberia | | | || | || | | | | | || | || | | Costa Rica: | 32 | 26 | 6 || 29 | 3 || 30 | 2 | Esparta | | | || | || | | --------------------------------------------------------------------------

========================================================================== Population | Scapular markings || Sacral | | || markings | |----------------------------||----------------------| | X | )( | ][ | Other || / | / | Other | -------------------------------------------------------------------------- Oaxaca: | 23 | 4 | 0 | 0 || 7 | 6 | 14 | Donaji-Sarabia | | | | || | | | | | | | || | | | Tabasco: | 53 | 2 | 0 | 0 || 19 | 11 | 23 | Teapa-Villahermosa| | | | || | | | | | | | || | | | Guatemala: | 45 | 6 | 0 | 0 || 16 | 14 | 21 | La Libertad | | | | || | | | | | | | || | | | Guatemala: | 32 | 0 | 0 | 0 || 26 | 2 | 4 | Finca Chama | | | | || | | | | | | | || | | | Guatemala: | 23 | 0 | 4 | 4 || 6 | 4 | 21 | Puerto Barrios | | | | || | | | | | | | || | | | Honduras: | 3 | 2 | 3 | 5 || 2 | 1 | 10 | Lago Yojoa | | | | || | | | | | | | || | | | Nicaragua: | 11 | 35 | 8 | 2 || 0 | 19 | 37 | La c.u.mplida | | | | || | | | | | | | || | | | Nicaragua: | 0 | 5 | 3 | 2 || 0 | 3 | 7 | Tipitapa | | | | || | | | | | | | || | | | Nicaragua: | 3 | 0 | 7 | 0 || 0 | 5 | 5 | Santo Thomas | | | | || | | | | | | | || | | | Costa Rica: | 0 | 0 | 12 | 0 || 0 | 0 | 12 | Tenorio-Tilaran | | | | || | | | | | | | || | | | Costa Rica: | 0 | 11 | 19 | 8 || 0 | 0 | 38 | Las Canas-Liberia | | | | || | | | | | | | || | | | Costa Rica: | 0 | 0 | 14 | 18 || 0 | 0 | 32 | Esparta | | | | || | | | --------------------------------------------------------------------------

[Footnote A: Longitudinal stripes present in two specimens.]

When this frog is active at night its dorsum is pale yellow; faint flecks are present in some individuals. The white dorsolateral line usually is evident in the tympanic region, but in many individuals a dorsal pattern of lines and other marks is not evident. By day the dorsum changes to yellowish tan or pale brown with dark brown or reddish brown markings (Pl. 13). The venter is white, and the vocal sac in breeding males is yellow. The iris is pale bronze with a brown tint anterior and posterior to the pupil.

_Remarks._--_Hyla microcephala underwoodi_ has had a confused nomenclatural history. The taxon was first named _Hyla microcephala_ by Boulenger (1898); this name was preoccupied by _Hyla microcephala_ Cope (1886). Cole and Barbour (1906) and Kellogg (1932) used the name _Hyla phlebodes_ Stejneger (1906) for specimens of this frog from Mexico. Dunn (1931, 1933, 1934) applied the name _Hyla underwoodi_ to Panamanian specimens that we identify as _Hyla phlebodes_. Smith (1951) named _Hyla microcephala martini_ from southern Mexico and Guatemala and considered the northern populations to represent a subspecies distinct from the Costa Rican _Hyla microcephala underwoodi_, despite the fact the Stuart (1935:39) stated that comparisons of specimens from El Peten, Guatemala, with the holotype of _Hyla underwoodi_ showed only trivial differences.

Much of the confusion regarding the name _Hyla underwoodi_ stems from the ill.u.s.tration given by Boulenger (1898:pl. 39, fig. 3) and reproduced by Taylor (1952:892), which shows a frog having a unicolor dorsum, dorsolateral white lines, and dark flanks. This pattern is in marked contrast to the pattern seen in most preserved specimens, which have the dorsum variously marked by dark brown lines or irregular marks. Smith (1951:185), in his description of _Hyla microcephala martini_ from southern Mexico, considered _H. underwoodi_ to be a subspecies of _H. microcephala_ that lacked dorsal dark markings.

Data acc.u.mulated in 1961 through field studies by the senior author at the type locality, Bebedero, and other localities in Guanacaste and Puntarenas provinces in Costa Rica provide a reasonable explanation of the differences in color pattern. As noted in the preceding description of this subspecies, at night the dorsal markings are not evident in many living individuals, whereas by day the dorsal markings are prominent. Most collectors prepare their specimens by day; consequently the majority of specimens have a p.r.o.nounced dorsal pattern. Of the frogs collected in Costa Rica in 1961, some specimens were preserved at night; others from the same series were preserved by day. The differences are striking. In those preserved at night, dorsal markings are faint, if present at all. Some specimens closely match the figure given by Boulenger (1898).

It is extremely doubtful if the frog described and ill.u.s.trated by Boulenger could be a.s.sociated with either _Hyla phlebodes_ or _H.

microcephala microcephala_. Individuals of the former species lack a dorsolateral white line and always have some dorsal markings evident at night; furthermore, _H. phlebodes_ is not known to occur on the Pacific lowlands. _Hyla microcephala microcephala_ occurs farther southeast. Since there is no reason to doubt the type locality of _H. underwoodi_, since specimens from the area around the type locality that have been preserved at night are like the holotype in pattern, and since the characteristics of the populations of the frogs in Guanacaste are the same as, or gradually blend into those of, populations in northern Central America and southern Mexico, the frogs from throughout the entire range can be referred to one taxon, the earliest name for which is _Hyla underwoodi_ Boulenger, which herein is considered to be a subspecies of _H. microcephala_ Cope.

_Distribution._--_Hyla microcephala underwoodi_ inhabits the Atlantic slopes and lowlands from southern Veracruz and extreme northern Oaxaca eastward across the base of the Yucatan Peninsula (possibly the species is extant in the northern part of the peninsula) to British Honduras and thence southeastward through the Caribbean lowlands and interior valleys in Honduras to central Nicaragua, where it apparently avoids the forested Caribbean lowlands and the dry Pacific lowlands of northwestern Nicaragua, but in the vicinity of Managua invades the Pacific lowlands and continues southward into northwestern Costa Rica as far as the Puntarenas Peninsula (Fig. 1). In Mexico and Guatemala the species has not been taken at elevations of more than 350 meters, whereas farther south it occurs at higher elevations--780 meters at Silencio, Costa Rica, 830 meters on Montana de Guaimaca, Honduras, 960 meters at Finca Tepeyac, Nicaragua, and 1200 meters at Finca Venecia, Nicaragua.

_Specimens examined._--1270, as follows: +Mexico+: Campeche: Balchacaj, FMNH 100406, UIMNH 20944-6; Encarnacion, FMNH 27069-70, 75784, MCZ 28360, 29637, UIMNH 20948-58, 20965, USNM 134264-5; Escarcega, UMMZ 122999; *7.5 km. W Escarcega, KU 71229-43; Laguna Alvarado, 65 km.

S Xpujil, KU 75084-9; Pacaitun, Rio Candelaria, FMNH 83118-20; *Tres Brazos, FMNH 113101-22, UIMNH 20947; 10 km. W Xpujil, KU 75082-3.

Chiapas: Palenque, UIMNH 47984, 49139-50, USNM 114973-8. Oaxaca: *5 km.

N Chiltepec, KU 87015-23; 3 km. N Donaji UMMZ 115249 (9); *3.7 km.

N Donaji, UMMZ 115250 (5); *43 km. N Matias Romero, UIMNH 42550-68; *3.5 km. N Palomares, TNHC 25185, 25321-31, 25341-68; 4.6 km. N Sarabia, UMMZ 115247 (2); *6.1 km. N Sarabia, UMMZ 115248 (11), *3 km.

N Tolocita, KU 39655; Tuxtepec, KU 87024-40. Tabasco: 24 km. N Frontera, MCZ 35665-70; 0.8 km. E Rio Tonola, TNHC 25189; Teapa, UMMZ 119218 (4); *2.7 km. N Teapa, UMMZ 119216 (4); *10 km. N Teapa, UMMZ 119217 (6); *11.5 km. N Teapa, UMMZ 119219; *15.2 km. N Teapa, UMMZ 119220 (4); *17.6 km. N Teapa, UMMZ 119221 (12), 3.3 km. S Villahermosa, UMMZ 119215 (12), *17.6 km. S Villahermosa, UMMZ 119214 (12).

Veracruz: 2.1 km. N Acayucan, UIMNH 42547-9; *6.4 km. NW Acayucan, UMMZ 115254 (14); 1.6 km. ESE Alvarado, UMMZ 115258 (39); *2.4 km. ESE Alvarado, UMMZ 115251 (2); *4.5 km. S Aquilera, UMMZ 115252 (21); *8 km. SW Coatzacoalcos, UMMZ 119213 (10); 2.2 km. E Cosoleacaque, UMMZ 119222 (26); 10 km. SE Hueyapan, UMMZ 115255; 0.8 km. S Lerdo de Tejada, UMMZ 122778; *3.6 km. NE Minat.i.tlan, TNHC 25150-2; 1.9 km. S Naranja, UMMZ 115253 (3); 4.5 km. NE Novillero, UMMZ 115256; San Andres Tuxtla, FMNH 113124-8, UIMNH 20942-3. Yucatan: Chichen-Itza, FMNH 36570, MCZ 2463 (2).

+British Honduras+: Cayo: 6.2 km. S El Cayo, MCZ 37885-92. Stann Creek: Stann Creek, FMNH 49068.

+Guatemala+: Alta Verapaz: 28.3 km. N Campur, KU 64578-90; Chinaja, KU 57425; Cubilquitz, UMMZ 90887, 90888 (4); Finca Chama, UMMZ 90879 (13), 90880 (4), 90881, 90882 (28), 90883 (12), 90884 (46), 90885 (39), 90886 (20); *Finca Tinaja, BYU 16032; Panzos, UMMZ 90889 (2).

Chiquimula: Chiquimula, UMMZ 98113; 2 km. N Esquipulas, UMMZ 106844.

El peten: La Libertad, KU 57447-97, 59907-11 (skeletons), MCZ 21461, UMMZ 75332 (13), 75333 (11), 75334 (14), 75335 (10); Piedras Negras, FMNH 113123, UIMNH 20966; *5 km. S Piedras Negras, USNM 114951-72; Tikal, UMMZ 117981 (2); Toocog, 15 km. SE La Libertad, KU 57426-46. El Quiche: Finca Tesoro, UMMZ 89165 (5). Huehuetenango: Finca San Rafael, 16 km. SE Barillas, FMNH 40917-9. Izabal: Puerto Barrios, FMNH 20004-7; 8 km. S Puerto Barrios, KU 57507-37, 59991 (eggs), 59992 (tadpoles); Quirigua, CAS 69657-701; 2.5 km. NE Rio Blanco, KU 57539; San Felipe, FMNH 35065. Zacapa: 14 km. ENE Mayuelas, KU 57502-6; 8 km.

ENE Rio Hondo, KU 57498-501.

+Honduras+: Atlantidad: La Ceiba, UMMZ 91948 (2), USNM 117593-600; Lancetilla, MCZ 17981. Cortes: Lago Yojoa, AMNH 54917-9, 54957, 55134, KU 64563-77. El Paraiso: Valle de Jamastran, AMNH 54807-12.

Francisco-Moranza: El Zamorano, AMNH 54873-81, KU 103223, UMMZ 123101; Montana de Guaimaca, AMNH 54900-4 (8); Ranch San Diego, 19 km. SW Guaimaca, AMNH 53939. Itibuca: Vieja Itibuca, AMNH 54912-3.

+Nicaragua+: Chontales: 3 km. SW Santo Tomas, KU 64770-9, 68308 (skeleton). Esteli: Finca Venecia, 7 km. N, 16 km. E Condega, KU 85296; 2.4 km. N Esteli, MCZ 28933-7. MANAGUA: 12-13 km. E Managua, KU 85297-301; *10 km. SW Tipitapa, UMMZ 119977 (10). Matagalpa: *Finca Tepeyac, 10.5 km. N, 9 km. E Matagalpa, KU 85302-3; Hacienda La c.u.mplida, KU 64780-96, 68309-11 (skeletons), UMMZ 116482 (8), 116483 (23), 116484 (3), 116485 (5), 119984 (3). Rivas: *Finca Amayo, 13 km.

S, 14 km. E Rivas, KU 85304-7; 16 km. S Rivas, MCZ 29011-7; *20.5 km.

SE Rivas, KU 85308-10; 5 km. SE San Pablo, KU 43111-4.

+Costa Rica+: Guanacaste: Arenal, USC 6254 (2); *3 km. W Bagaces, USC 7019 (10); *3 km. NE Boca del Barranca, USC 8017 (21), *Finca San Bosco, USC 6272 (6), 6276 (3); *Guayabo de Bagaces, USC 7022 (4), 7023 (3), 7025; 12 km. S La Cruz, USC 8091 (2); *Laguna Arenal, USC 6262; *27 km. N Las Canas, USC 8171 (6); *16 km. E Las Canas, KU 102252-8; 16 km. SSE Las Canas, KU 65090-5; *20 km. SE Las Canas, KU 102251; Liberia, KU 30827-39; *7.3 km. N Liberia, USC 8096 (4); *10 km. N Liberia, USC 8085 (9); *7.5 km. SE Liberia, KU 65102-8, 68621-2 (skeletons); *14.7 km. S Liberia, USC 8238 (3); *4 km. W Liberia, KU 36847-57; 2 km. S Nicoya, USC 8230; *3-10 km. ESE Playa del Coco, USC 8012 (16), 8137 (14); *21.6 km. ESE Playa del Coco, USC 8138 (13); *Penas Blancas, KU 102247-50; *Rio Bebedero, 5 km. S Bebedero, KU 65089; *Rio Higueron, USC 7168 (2); Santa Cruz, USC 8232 (2); *Silencio, USC 6248; *Tenorio, KU 32313; Tilaran, KU 36858-60; *2 km.

E Tilaran, KU 86403, *5 km. NE Tilaran, KU 36840-6 USC 6269.

Puntarenas: Barranca, KU 32305-12, *5 km. WNW Barranca, UMMZ 119976 (2); *10 km. E Esparta, KU 86400-2; 1 km. WNW Esparta, KU 65101; *4 km.

WNW Esparta, KU 65088; *10 km. WNW Esparta, KU 65063-87, 68616-20 (skeletons); *12 km. WNW Esparta, KU 65096-100, USC 8251; 21.8 km.

W San Ramon, USC 8242 (15).

+Hyla robertmertensi+ Taylor

_Hyla robertmertensi_ Taylor, Proc. Biol. Soc. Washington, 50:43, April 21, 1937 [Holotype.--CNHM 100096 (formerly EHT-HMS 2270) from Tapachula, Chiapas, Mexico; H. M. Smith and E. H. Taylor collectors]. Smith and Taylor, Bull. U. S. Natl. Mus., 194:84, June 17, 1948; Univ. Kansas Sci. Bull., 33:326, March 20, 1950.

Mertens. Senckenbergiana, 33:170, June 15, 1952; Senckenbergischen Naturf. Gesell., 487:30, December 1, 1952.

Stuart, Contr. Lab. Vert. Biol., Univ. Michigan, 68:47, November, 1954. Duellman, Univ. Kansas Publ., Mus. Nat. Hist., 13:63, August 16, 1960. Duellman and Hoyt, Copeia, 1961 (2): 417, December 19, 1961. Porter, Herpetologica, 18:168, October 17, 1962. Stuart, Misc. Publ. Mus. Zool., Univ. Michigan, 122:36, April 2, 1963. Duellman and Trueb, Univ. Kansas Publ., Mus. Nat.

Hist., 17:348, July 14, 1966.

_Diagnosis._--Brown lateral stripe wide, including loreal region and entire tympanum, extending to groin, bordered above by narrow white line; dorsum unicolor or with pair of dark lines (or rows of dashes) usually extending only to the sacral region; shanks having dark flecks, no transverse bars; interorbital bar lacking.

_Description and Variation._--Males attain a maximum snout-vent length of 26.4 mm. in Oaxaca, whereas in a sample from Acacoyagua, Chiapas, the largest male has a snout-vent length of 25.7 mm., and from La Trinidad, Guatemala, 24-6 mm. Specimens from the western part of the range (eastern Oaxaca) have slightly smaller heads and proportionately larger tympani than the more eastern populations (Table 1).

The color pattern shows little variation, except in the nature of the dorsal markings. In a few specimens from throughout the range, but especially in the eastern part of the range, the dorsum lacks markings between the dorsolateral white lines. In most specimens the dorsal pattern consists of flecks or dashes arranged in two parallel longitudinal rows, and in some specimens the marks are fused into parallel lines. Small brown flecks are present on the dorsal surfaces of the shanks; in some specimens these flecks tend to form a longitudinal stripe on the shank. An interorbital dark mark is invariably absent.

When active at night _Hyla robertmertensi_ is pale yellow above with a white dorsolateral line and pale brown lateral stripe; the dorsal markings are faint. By day the dorsum is yellowish tan with brown markings. The dorsolateral stripe is creamy white, and the lateral stripe is dark brown (Pl. 14). The venter is white, and the iris is dull bronze. In breeding males the vocal sac is yellow.

_Remarks._--Although this species superficially resembles _Hyla microcephala microcephala_, the latter is easily distinguished by the narrow brown lateral stripe, as compared with the much wider stripe in _H. robertmertensi_. No other hylids in northern Central America and southern Mexico can be confused with this species.

_Distribution._--_Hyla robertmertensi_ inhabits the Pacific slopes (to elevations of 700 meters) and lowlands from eastern Oaxaca (east of the Plains of Tehuantepec) southeastward to central El Salvador. The species also occurs in the Cintalapa Valley (Atlantic drainage) in southwestern Chiapas (Fig. 2.) The distribution seems to be limited on the northwest and southeast by arid environments. The region in which _Hyla robertmertensi_ lives is characterized by higher rainfall and more luxuriant vegetation than occur on the Plains of Tehuantepec or on the Pacific lowlands of eastern El Salvador and southern Honduras.

In addition to the localities listed below, Mertens (1952:30) recorded the species from Hacienda Cuyan-Cuya, Depto. Sonsonate, El Salvador.

[Ill.u.s.tration: Fig. 2. Map showing locality records for _Hyla robertmertensi_.]

_Specimens examined._--490, as follows: +Mexico+: Chiapas: Acacoyagua, USNM 114754-61; *2 km. W Acacoyagua, UMMZ 87843 (28), 87844 (50), 87845 (50), 87846 (45), 87847 (27), 87848 (3); 32 km. N Arriaga, KU 57619-24, 59917-8 (skeletons); Asuncion, FMNH 100413, 100501-4, UIMNH 26989-90, USNM 134267; *La Esperanza, USNM 114737-48, 114750-3, 17 km.

S Las Cruces, KU 57625-49, 59997 (eggs); 8.5 km. N Puerto Madero, UMMZ 119981 (2); *11.7 km. N Puerto Madero, UMMZ 119982; Tapachula, FMNH 100096, UIMNH 26987; *11 km. S Tapachula, KU 57605-18, 59916 (skeleton); Tonola, FMNH 27073, 100505-10, UIMNH 26988. Oaxaca: Tapanatepec, UMMZ 115245 (2), *1.6 km. E Tapanatepec, UMMZ 115244 (14); *4.3 km.

E Tapanatepec, UIMNH 38368-9; *7.5 km. W Tapanatepec, UMMZ 115246 (39); 12.8 km. W Tapanatepec, KU 65007-14; 7.2 km. WNW Zanatepec, UMMZ 115243 (77); *13.6 km. WNW Zanatepec, TNHC 25213-22; 22.7 km.

WNW Zanatepec, TNHC 25203-9.

+Guatemala+: Jutiapa: Jutiapa, UMMZ 106848; La Trinidad, UMMZ 107733 (23). Retalhueleu: Casa Blanca, UMMZ 107732.

+El Salvador+: La Libertad: 16 km. NW Santa Tecla, KU 44112. San Salvador: 21.9 km. N San Salvador, UMMZ 119983 (6).

+Hyla phlebodes+ Stejneger

_Hyla phlebodes_ Stejneger, Proc. U. S. Natl. Mus., 30:817, June 4, 1906 [Holotype.--USNM 2997 from "San Carlos," Costa Rica; Burgdorf and Schild collectors]. Taylor, Proc. Biol. Soc.

Washington, 50:44, April 21, 1937; Univ. Kansas Sci. Bull., 35:888, July 1, 1952; Univ. Kansas Sci. Bull., 39:25, November 18, 1958. Fouquette, Evolution, 14:484, December 16, 1960.

Duellman and Trueb, Univ. Kansas Publ., Mus. Nat. Hist., 17:348, July 14, 1966.

_Hyla underwoodi_, Dunn, Occas. Papers Boston Soc. Nat. Hist., 5:413, October 10, 1931; Occas. Papers Boston Soc. Nat. Hist. 8:72, June 7, 1933; Amer. Mus. Novitiates, 747.2, September 17, 1934, Gaige, Hartweg, and Stuart, Occas. Papers Mus. Zool., Univ.

Michigan, 357:5, October 26, 1937. Breder, 1946, Bull. Amer. Mus.