Oedipina nimaso, Boza-Oviedo, Eduardo, Rovito, Sean M., Chaves, Gerardo, García-Rodríguez, Adrián, Artavia, Luis G., Bolaños, Federico & Wake, David B., 2012

Boza-Oviedo, Eduardo, Rovito, Sean M., Chaves, Gerardo, García-Rodríguez, Adrián, Artavia, Luis G., Bolaños, Federico & Wake, David B., 2012, Salamanders from the eastern Cordillera de Talamanca, Costa Rica, with descriptions of five new species (Plethodontidae: Bolitoglossa, Nototriton, and Oedipina) and natural history notes from recent expeditions, Zootaxa 3309, pp. 36-61 : 50-51

Oedipina nimaso sp. nov.

Nimaso Worm Salamander Figure 6

Holotype. UCR 8391, a subadult male from Cerro Nimaso , Prov. Limón, Costa Rica, 1093 m, collected by D. Robinson, Federico Bolaños, and Gilbert Barrantes on April 14, 1984.

Diagnosis. A small, extremely slender member of Oedipina (Oedopinola) , based on having greater than 14 but fewer than 20 trunk vertebrae ( García-París & Wake 2000; McCranie et al. 2008), distinguished from other members of that clade by the combination of its small size, slender habitus, its long pointed snout and very narrow hands and feet with pointed digital tips. Distinguished from Costa Rican and Panamanian members of the clade as follows: from O. carablanca by smaller size, very narrow pes (vs. very broad and webbed in O. carablanca ) and manus relative to SVL with reduced numbers of phalanges (0-1-2-1 manus vs. 1-2-3- 2 in O. carablanca ; 0-1-2-1-1 pes vs. 1-2-3-(2,3)- 2 in O. carablanca ) and little white dorsal pigment vs. extensive white pigment on head and body in O. carablanca ; from O. parvipes and O. maritima by narrower and more syndactylous hands and feet, rounded snout and relatively large and numerous maxillary teeth (max 8 in O. maritima , fewer than 5 in Panamanian O. parvipes ); from O. alleni in being much smaller and less robust with much narrower pes and shorter digits, and in having more maxillary teeth (20 vs. 5 or fewer in O. alleni ); from O. savagei by being less robust and in having shorter limbs (limb interval 9.5 vs. less than 7 in O. savagei ) and narrower pes (1.2 vs. 1.9 in O. savagei ), and in lacking white pigment on the back of the head and a dorsal stripe on the trunk; from O. fortunensis by having shorter limbs (limb interval 9.5 vs. 8 in O. fortunensis ), narrower pes (1.2 mm vs. 1.7 in O. fortunensis ), and a shorter, more pointed head (SL/SG = 6.4 vs. 5.2 in O. fortunensis ); and from O. complex by having a longer tail (SVL/TL less than 0.73 vs. 0.89 in O. complex ), broader head (SVL/HW 8.6 vs. 10.2 in O. complex ) and narrower pes with a long, pointed third toe (vs. short rounded toe in O. complex ).

Description. A diminutive, slender species compared to other Oedopinola. Sole specimen, the holotype, has a SL of 30.8 mm. Holotype very slender ( Fig. 6 ) with narrow head (SL/HW 8.6) and rather long snout (SL/SG = 6.4) that is more rounded than pointed. Eyes small and only slightly protuberant. Limbs long and slender (SL/HLL = 4.5) and the right hindlimb is missing. Manus and pes flat and very narrow (SL/FW = 25.7), with digits poorly defined and fused together. Longest digit with long, sharply pointed tip that is slightly bent in a preaxial direction. Relatively numerous maxillary teeth relatively large and single premaxillary tooth is long and hooked, suggesting that individual is near or at sexual maturity.

Measurements (in mm), limb interval and tooth counts of the male holotype ( Table 2 ). HW 3.6, SG 4.8, HD 1.6, EW 0.4, EL 1.1, ES 1.3, ED 0.7, IC 1.0, IO 1.2, length of groove extending posteriorly from eye 0.8, distance between nuchal groove and gular fold 1.4, SF 7.3, IN 1.0, external naris to snout 0.4, SP 0.3, SL 30.8, SAV 26.6, AX 19.8, LI 9.5, TL 42.0 (tail broken at tip, only slightly longer in life), tail width at base 2.1, tail depth at base 1.8, FLL 6.2, HLL 6.9, HAW 1.0, FW 1.2, T5 0.8, T3 1.1, parotoid width 1.4, parotoid length 2.9, nostril diameter 0.6. Number of teeth: PMT 1, MT 9/11, VT 6/6.

Coloration of the holotype in alcohol. Brown to reddish-brown generally, with small amount of whitish pigment on head, mainly concentrated between eyes. Venter lighter than other surfaces and covered with tiny whitish patches or speckles.

Habitat and range. Known only from the type locality. The locality is essentially mature forest within a sparsely inhabited indigenous reserve. The forest is very humid tropical forest in a transition zone to premontane forest.

Etymology. The scientific name is a noun in apposition and refers to the type locality at Cerro Nimaso .

Remarks. This specimen is badly desiccated. Osteological information has been derived from radiographs. There are 18 trunk vertebrae, one sacral, two caudosacral and 31 caudal vertebrae, with the very tip of the tail missing. The phalangeal formula for the manus is 0-1-2-1 and for the pes is 0-1-2-1-1. The basic formula for Oedipina is 1-2-3-2, and 1-2-3-3-2 ( Wake 1966, Brame 1968, García-París & Wake 2000) so there has been a considerable reduction in this species. Some other members of Oedopinola from Costa Rica and Panama also have relatively few phalanges. The last trunk vertebra that bears ribs is number 16. Mesopodial elements are unmineralized cartilage. A preorbital process is present on the vomers. Nasals are moderately protuberant and are the anterior-most skeletal bones. The skull bones are fully articulated and well-developed, suggesting a near adult state of development, so this is likely a miniaturized species compared to other members of its genus.

Figures

FIGURE 6. A) Dorsal and B) ventral views of preserved holotype (UCR 8391) of Oedipina nimaso. C) Dorsal view of left hand and D) left foot of holotype. Photos A and B by Humberto Lezama, C and D by A. García-Rodríguez. The bar in hand and feet are 1 mm length.