The tympanum is proportionately larger in females than in males; the variation in size and proportions is given in Table 2. The total number of prevomerine teeth varies from 13 to 18 (mean, 15) in five adult males and from 10 to 12 (mean 11) in two females.

The testes in all adult males are granular, ovoid in shape, and greatly enlarged. The lengths of the left testis in each of the five males are 11.0 to 23.5 (mean 14.6) mm.

_Comparisons._--On the basis of external appearance and certain cranial characters (large frontoparietal fontanelle, broad sphenethmoid, large nasals broadly separated medially having thin lateral processes articulating with the palatines, short squamosal not articulating with the maxillary, and quadratojugal present and articulating with the maxillary), _Hyla altipotens_ can be a.s.sociated with the _Hyla taeniopus_ group (Duellman, 1965, Lynch and Smith, 1966). _Hyla altipotens_ can be distinguished from all of the other members of the group by its narrow head, pointed snout in both s.e.xes, and uniformly yellow throat and belly.

Small brown individuals of _Hyla altipotens_ superficially resemble adult _Hyla pinorum_. The latter species has a covered tympanum, less webbing on the hands, and a short, blunt snout.

_Remarks._--This stream-breeding frog is like _Hyla taeniopus_ in having greatly enlarged testes, which possibly through the production of vast quant.i.ties of sperm are an adaptation for successful breeding in torrential streams (Duellman, 1965:164).

All individuals were found in trees and bushes near streams in cloud forest at night in February. The type locality is the same as that of _Hyla pentheter_ and _Hyla th.o.r.ectes_, discovered by Kraig Adler in June, 1964. Our field work there in February, 1966, resulted in finding _Hyla altipotens_, _H. pellita_, and _Ptychohyla leonhardschultzei_, but no individuals of the species found by Adler. A visit to the same locality in August, 1966, revealed no individuals of either _H.

altipotens_ or _pellita_; instead _pentheter_ and _th.o.r.ectes_ were found along the stream.

Duellman (1965:166) listed a specimen (TCWC 16184) of _Hyla chaneque_ from Los Fustes, 3 kilometers east of San Sebastian, Oaxaca.

Reexamination of this specimen reveals that it is _Hyla altipotens_.

The frog was obtained by Dilford Carter on April 29, 1960; it was under a rock at the edge of a stream in an oak-pine-cypress a.s.sociation at an elevation of 1800 meters.

The specific name _altipotens_ is Latin, meaning mighty, here used in allusion to the supposed potentiality of fertilization by the production of vast quant.i.ties of sperm in the large testes.

Plectrohyla hartwegi new species

Plate 19

_Holotype._--Adult male, UMMZ 94428, from Barrejonel (19 kilometers west of Chicomuselo), Chiapas, Mexico, elevation 1000 meters, obtained on June 12, 1941, by Eizi Matuda.

_Paratypes._--Two subadult males, KU 58873 from Paraje El Triunfo, north of Mapastepec, Chiapas, Mexico, elevation 2050 meters, obtained on May 12, 1960, by Miguel Alvarez del Toro, and UIMNH 40837 from Cerro Azul Oaxaca, Mexico, obtained on March 7, 1956, by Thomas MacDougall.

_Diagnosis._--A _Plectrohyla_ having a bifid prepollex, bold mottling on flanks and ventral surfaces of shanks, and vertical dark bars on anterior and posterior surfaces of thighs, and lacking vocal slits and outer tarsal fold.

_Description of holotype._--Adult male having a snout-vent length of 63.8 mm.; tibia length 34.9 mm., 54.7 per cent of snout-vent length; foot length (measured from proximal edge of inner metatarsal tubercle to tip of longest toe) 31.1 mm., 48.7 per cent of snout-vent length; head length 19.7 mm., 30.9 per cent of snout-vent length; head width 22.6 mm., 35.4 per cent of snout-vent length. Snout short, distance from level of anterior edge of orbit to tip of snout 70.6 per cent of length of eye; snout in lateral profile angular, sloping abruptly from nostrils to jaw, in dorsal profile bluntly rounded, lacking rostral keel; canthal ridge thickened; loreal region deeply concave; lips thick, barely flared. Nostrils small, barely protuberant, directed anterolaterally, situated about two-thirds distance from eye to tip of snout; internarial distance 5.6 mm. internarial area barely depressed near convergence of canthal ridges; top of head flat; interorbital distance 6.4 mm., 28.3 per cent of head width; diameter of eye 6.8 mm.; width of eyelid 5.5 mm., 24.3 per cent of head width. Heavy dermal fold extending posteriorly from posterior edge of orbit, covering upper edge of tympanum; two thinner folds extending ventrally from longitudinal heavy fold covering posterior edge of tympanum; anterior and ventral edges of tympanum distinct; length of tympanum 2.9 mm., 42.6 per cent of diameter of eye.

Axillary membrane absent; arms robust, forearm not noticeably heavier than upper arm; distinct transverse fold on wrist. Fingers long, moderately slender; length of fingers from shortest to longest, 1-2-4-3; discs moderately large, that on third finger larger than tympanum; webbing vestigial; subarticular tubercles small, conical; terminal tubercle on fourth finger somewhat flattened; supernumerary tubercles small, in one row on proximal segment of fourth finger and in two rows on proximal segments of other fingers; prepollex greatly enlarged, barely bifurcate; spines not protruding through skin; distal spine much longer than proximal one (Fig. 2). Heels overlap by about one-third length of shank when hind limbs adpressed; tibiotarsal articulation extends slightly beyond snout; heavy transverse dermal fold on heel; inner tarsal fold heavy, extending full length of tarsus; outer tarsal fold absent; inner metatarsal tubercle high, elliptical, visible from above, outer metatarsal tubercle absent. Toes long, slender; length of toes from shortest to longest, 1-2-5-3-4; fifth toe nearly as long as third; discs small; subarticular tubercles small, round; supernumerary tubercles small, in single row on proximal segment of each digit; toes about three-fourths webbed; webbing extending from base of disc of first toe to base of penultimate phalanx of third, from base of disc of third to base of penultimate phalanx of fourth to base of disc of fifth toe.

[Ill.u.s.tration: FIG. 2. Palmar view of prepollical spine of right hand of _Plectrohyla hartwegi_ (UMMZ 94428). 5.]

a.n.a.l opening directed posteroventrally at level of mid-thigh; a.n.a.l sheath long with membranous connection to posterior surfaces of thighs.

Skin on dorsal surfaces finely tuberculate; that on throat, chest, belly, and ventral surfaces of thighs granular, that on ventral surfaces of arms and shanks smooth. Tongue nearly round, free posteriorly for about one-fourth its length, barely notched behind. Upper jaw shallowly notched medially. Maxillary-premaxillary teeth 38-35; prevomerine teeth 5-5, situated on small elliptical elevations between quadrangular choanae; vocal slits absent.

Color (in preservative): uniform dull brown above and creamy yellow below; flanks brown with creamy yellow mottling and dark brown spots in groin; anterior surfaces of thighs creamy yellow with two broad, vertical, dark brown bars proximally and two narrower, dull brown bars distally; posterior surfaces of thighs brown with dark brown vertical bars, inters.p.a.ces cream-colored or brown. Ventral surfaces of shanks creamy yellow with bold brown reticulations.

_Variation._--The paratypes are smaller, having snout-vent lengths of 48.3 and 41.8 mm. In these specimens the ratio of the length of the tibia to the snout-vent length is 55.9 and 57.9 per cent, and the ratio of the diameter of the tympanum to the diameter of the eye is 47.3 and 43.6 per cent, respectively. Both specimens have 4-4 prevomerine teeth; one specimen has 37-36, and the other has 40-37, maxillary-premaxillary teeth. In these small specimens the supratympanic fold is thin, and the arms are not so robust as in the holotype. In one specimen (KU 58873) the tongue is not notched posteriorly. The terminal subarticular tubercle on each fourth finger is broad and flattened in UIMNH 40837, but conical in KU 58873. Both specimens have bold creamy-yellow and dark brown mottling on the flanks and dark brown reticulations on the ventral surfaces of the shanks. There are two dark brown vertical bars on the anterior and posterior surfaces of each thigh in KU 58873 and three bars on each surface in UIMNH 40837.

_Comparisons._--_Plectrohyla hartwegi_ differs from all known species in the genus by having boldly mottled flanks, dark reticulations on the ventral surfaces of the shanks, and dark vertical bars on the shanks. In all of the other species the anterior and posterior surfaces of the thighs are unmarked, and the flanks are either plain or marked with small spots or flecks. Structurally, _P. hartwegi_ belongs in the _guatemalensis_ group of the genus, containing _avia_, _glandulosa_, _guatemalensis_, and _pycnochila_. The species in this group lack vocal slits and have either large, rectangular, or bifid prepollices.

_Plectrohyla hartwegi_ differs from all of these species, except _pycnochila_, by having a tuberculate, instead of a smooth, dorsum, and _hartwegi_ differs from _pycnochila_ by having a bifid, instead of a rectangular, prepollex.

_Remarks._--The known distribution of _Plectrohyla hartwegi_ includes three localities at elevations of 1000 to 2050 meters in the Sierra Madre of Chiapas and extreme eastern Oaxaca. The specimen from Paraje El Triunfo was found in a rocky stream in cloud forest at an elevation of 2050 meters. One _Plectrohyla sagorum_ was obtained from the same stream.

Eizi Matuda sent the holotype to the late Dr. Norman Hartweg, who recognized that the specimen was unique but was reluctant to name the species on the basis of a single specimen. Now that two additional specimens are available, it seems appropriate to a.s.sociate Hartweg's name with this new species of _Plectrohyla_, a genus that Hartweg first adequately defined.

LITERATURE CITED

ADLER, K.

1965. Three new frogs of the genus _Hyla_ from the Sierra Madre del Sur of Mexico. Occas. Papers Mus. Zool. Univ.

Michigan, 642:1-18, pl. 1, December 16.

DUELLMAN, W. E.

1960. Synonymy, variation, and distribution of _Ptychohyla leonhardschultzei_ Ahl. Studies of American hylid frogs, IV.

Herpetologica, 16:191-197, September 23.

1964. A review of the frogs of the _Hyla bistincta_ group.

Univ. Kansas Publ. Mus. Nat. Hist., 15:469-491, March 2.

1965. Frogs of the _Hyla taeniopus_ group. Copeia, 2:159-168, June 25.

STARRETT, P.

1966. Rediscovery of _Hyla pictipes_ Cope, with description of a new montane stream _Hyla_ from Costa Rica. Bull. South.

California Acad. Sci., 65 (1):17-28, March.

_Transmitted July 11, 1967._

[Ill.u.s.tration: PLATE 17 Upper figure, _Hyla xanthosticta_ (KU 103772); lower figure, _Hyla pseudopuma infucata_ (KU 101770). 2.]

[Ill.u.s.tration: PLATE 18 Upper figure, _Hyla pellita_ (KU 100973); middle figure, _Hyla pellita_ (KU 100970); lower figure, _Hyla siopela_ (KU 100977). 2.]

[Ill.u.s.tration: PLATE 19 Upper figure, _Hyla altipotens_ (KU 101001); lower figure, _Plectrohyla hartwegi_ (UMMZ 94428). 1.]

31-9420