Geophis brachycephalus

Savage, Jay M. & Watling, James I., 2008, Not so rare snakes: a revision of the Geophis sieboldi group (Colubridae: Dipsadinae) in lower Central America and Colombia, Zoological Journal of the Linnean Society 153 (3), pp. 561-599 : 582-583

GEOPHIS BRACHYCEPHALUS COMPLEX GEOPHIS BRACHYCEPHALUS ( COPE, 1871)

Colobognathus brachycephalus Cope, 1871: 211 (Type Locality: Costa Rica: San José: San José, 1160 m; Holotype: ANSP 3337 , a juvenile male).

Colobognathus dolichocephalus Cope, 1871: 211 (Type locality: Costa Rica: San José: nr San José, c. 1160 m; Holotype: ANSP 3306 ).

Geophis moestus Günther, 1872: 15 (Type Locality: Costa Rica: Cartago: Cartago, 1435 m; Holotype: BMNH 1946.1.6.53).

Catastoma chalybeum Günther, 1872: 16 .

Elapoidis brachycephalus Cope, 1885: 386 .

Elapoidis dolichocephalus Günther, 1893: 87 .

Geophis chalybaea var. quadrangularis Günther, 1893: 89 , pl. 33, fig. B (Type Locality: Costa Rica: Cartago: Cartago, 1435 m; Holotype: BMNH.

Catastoma brachycephalum Cope, 1875: 147 .

Catastoma dolichocephalum Cope, 1875: 147 .

Dirosema brachycephalum Boulenger, 1894: 299 .

Rhabdosoma moestum Cope, 1887: 85 .

Geophis hoffmanni Boulenger, 1894: 319 (in part).

Geophis brachycephalus Slevin, 1942: 474 (in part); Dunn, 1942: 4 (in part); as first reviser Dunn selected Colobognathus brachycephalus over Colobognathus dolichocephalus both of Cope, 1871; Downs, 1967: 146, fig. 19 (in part); Savage, 2002: 602, pls 369–70 (in part); Myers, 2003: 39; Campbell & Lamar, 2004, pl. 119; Solórzano, 2004: 276, figs 75, 76 (in part).

Geophis bakeri Taylor, 1954: 689 (Type Locality: Costa Rica: Alajuela: Sarapiquí: Isla Bonita , 1200 m; Holotype: KU 31983 , an adult female).

Geophis nigroalbus Downs, 1967: 146 .

Geophis , species inquirenda Myers, 2003: 38, fig. 19 (in part).

Diagnostics: This species is characterized by having the following combination of features: (1) ventrals in males 129–140.0 ± 4.2–149, in females 136–141.7 ± 2.5–147; subcaudals in males 35–39.6 ± 3.4–48, in females 29–33.5 ± 2.2–39; ventrals plus subcaudals in males 171–179.6 ± 4.5–190, in females 169–175.3 ± 3.2–181; (2) uniform black dorsum and upper surface of tail or with red longitudinal stripes that may be fragmented by suffusions of dark pigment or with a blotched/banded pattern on at least the posterior three-quarters of the body that continues onto the upper surface of the tail; (3) hemipenes slightly bilobed, capitulum moderately long but slender, about 2.5 times length of truncus on asulcate side.

Remarks: The geographical distribution of the three colour patterns in this species was commented on by Downs (1967). The additional material requires some revisions to his discussion. Only uniform coloured snakes are known from the Cordillera de Tilarán, Volcán Poás, the passes between Volcán Poás and Volcán Barva and Volcán Barva and Volcán Irazú, and on the Atlantic slope of the Cordillera Central. Only specimens with the blotched/banded pattern are known from along the Atlantic slope at Alajuela: Fortuna (250 m), Limón: La Emilia, near Guápiles (260 m), Alto Guayacán (750 m), and El Tigre (680 m). Uniform and blotched/banded snakes co-occur on the Atlantic slope of the Cordillera de Tilarán at Alajuela: Reserva San Ramón (660 m) and Cordillera de Talamanca at Cartago: Moravia de Chirripó (1116 m). The striped pattern predominates on the Mesata Central and the Pacific slope of Volcán Barva and co-occurs with uniform patterned snakes on the slopes of Volcán Turrialba and in the area south-west of Cartago at: Cangreja (1680 m) and Palo Verde (1590 m). The striped pattern co-occurs with the banded/blotched pattern at San José: San José (1190 m), and Cartago: Turrialba (640 m) area. The striped pattern also occurs in one specimen from the Pacific lowland locality of Puntarenas: Golfito (13 m). Apparently all three patterns co-occur at Cartago: Cartago (1453 m). The pattern in which the stripes are suffused by black pigment and reduced to a series of small ‘spots’ is known from one specimen from the lowland locality of Limón: Guápiles (262 m) and two from higher elevations at Cartago: Cervantes (1441 m) and San José: Granadilla (1410 m).

We have some reservations regarding the record of the striped female ( UF 55309 ) from Puntarenas: Golfito (c. 13 m) in the Pacific lowlands. This site is many kilometres from any upland locality ( Fig. 14 ) for the species. As this is a semifossorial form it seems possible that the snake might have been transported in soil from upland Costa Rica to the lowlands. Such a thought has also crossed our minds regarding snakes of this taxon from the Atlantic lowlands in the area of Limon: Guápiles, 260 m, which have a blotched/banded pattern ( ANSP 21401 ) or the stripes reduced to small spots ( UCR 11139). Alternatively, these animals may have been washed down from higher elevations during the wet season .

Distribution: Found in a broad elevational range in areas currently or originally covered by tropical lowland wet forest and premontane and lower montane moist and wet forests and rainforest in Costa Rica; also in the tropical premontane rainforest of western Panama, 13–2115 m ( Figs 14 , 15 ).

Figures

Figure 14. Geographical distribution of two species of Geophis in Costa Rica.

Figure 15. Geographical distribution of three species of Geophis in western Panama. Geophis tectus sp. nov. is virtually sympatric with G. brachycephalus in the upper Río Chirripó drainage and with G. talamancae near Boquete.