Taeniophallus, COPE

SCHARGEL, WALTER E., RIVAS FUENMAYOR, GILSON & MYERS, CHARLES W., 2005, An Enigmatic New Snake from Cloud Forest of the Península de Paria, Venezuela (Colubridae: Genus Taeniophallus?), American Museum Novitates 3484, pp. 1-23 : 14-16

TAENIOPHALLUS COPE

This genus may not be monophyletic, but data are insufficient for firm conclusions. Three species groups can be recognized for discussion.

1. TAENIOPHALLUS BREVIROSTRIS AND TAENIOPHALLUS NICAGUS: Cope’s description of the then monotypic Taeniophallus (type species Lygophis nicagus , type locality unknown) was based partly on material of ‘‘ Rhadinaea ’’ brevirostris (fide Myers, 1974: 208); these two snakes were long confused until the rediscovery of T. nicagus as a South American snake ( Myers and Cadle, 1994: 4). Sufficient material has been accumulated for more detailed comparisons and elucidation of geographic ranges of T. brevirostris and T. nicagus (Myers and Cadle, in prep.).

They are small snakes, less than 500 mm in total length, usually with a broad middorsal stripe having undulating or serrated edges. Dorsal scale formula 17­17­15; apical pits often present. There are consistently 8 supralabials (variation is rare), with the 2nd touching the loreal and the 3rd–5th touching the eye. There are about 12–16 prediastemal maxillary teeth. Striking similarity in color pattern and morphology is suggestive of close relationship. Hemipenial differences, although remarkable, do not necessarily contradict such a relationship.

Taeniophallus nicagus is characterized by an undivided sulcus spermaticus (fig. 8B). Taeniophallus brevirostris has a bifurcated sulcus, but one branch is shorter than the other (fig. 8A). These conditions are rare or unique among Neotropical dipsadine and xenodontine colubrids. Shortening and eventual loss of one branch seems the likely explanation for the simple sulcus in T. nicagus . Neither brevirostris nor nicagus has an interspinal nude area on the asulcate side of the hemipenis.

2. TAENIOPHALLUS OCCIPITALIS : This is a distinctive species that is set off by a low number of scale rows (15­15­15 or 15­15­13, apical pits not detected) and an unusual anteriorly blotched to posteriorly spotted color pattern ( Myers, 1974: 209, figs. 46E, 48). It is a small snake, with total length approaching (and probably exceeding) 500 mm. There are consistently 8 supralabials, with the 2nd touching the loreal and the 3rd–5th touching the eye. There are 13–15 prediastemal maxillary teeth (N 5 12 specimens).

There is a distal interspinal nude area on the asulcate side of the single or slightly bilobed hemipenis, but it is quite short, being set off proximally by a very large spine at midorgan (fig. 9D) and ending distally deep under the overhanging edge of the capitulum. The papillae on the calyces gradually become thick and spinulate over the asulcate side of the capitulum, becoming largest near the edge of the capitulum, where a horizontal row of large soft spinules overhangs the distal end of the short interspinal nude gap.

Taeniophallus occipitalis resembles T. poecilopogon (see below) in having a conspicuous pale canthal line, but its closest relationships may well be with T. brevirostris and T. nicagus . The everted hemipenes of T. brevirostris and T. occipitalis are more different than had been suspected from study of retracted organs, but similar ‘‘thick, knoblike spinules’’ were noted on the asulcate side of the capitulum of some retracted organs of both species ( Myers, 1974: 205, 211), and the ‘‘gigantic calyx’’ or pocket in the lower edge of the capitulum of T. brevirostris may well be a homolog of the very deep but proximally open capitulate overhang in T. occipitalis . Aspects of the dorsal color pattern in some specimens of T. occipitalis suggest the possibility of derivation from a brevirostris ­ nicagus ­like ancestor (Myers and Cadle, unpubl.).

3. TAENIOPHALLUS AFFINIS GROUP: This comprises the four southernmost species of the old Rhadinaea brevirostris group, namely Taeniophallus affinis , T. bilineatus , T. persimilis , and T. poecilopogon . Myers (1974) had available fewer than 20 specimens of these (1– 8 specimens per species), but, in a series of papers, Di­Bernardo and Lema (1986 – 1991) subsequently presented data on some 200 specimens (9–110 per species), extending the known variation and geographic ranges, and confirming Myers’ placement of two older names ( Liophis insignissimus , Rhadinaea beui ) in the synonymy of ‘‘ Rhadinaea ’’ persimilis .

These are rather small snakes, seldom exceeding 500 mm in total length, except for the medium­sized Taeniophallus affinis , in which males exceed 600 mm and females 700 mm in total length. There are 17 dorsal scale rows without reduction; apical pits appear to be absent in the affinis group. 5

There are 7 supralabials, with the 2nd in contact with the loreal and with the 3rd–4th consistently touching the eye. Deviation from this pattern is rare (one specimen of T. bilineatus, MZUSP 4500, has 8 supralabials on one side only, with the 2nd–3rd touching the loreal but with the 3rd–4th in the orbit as normal).

A vertebral dark line or a wider nonundulatory middorsal stripe present or absent; a tendency for a thin pale line or row of pale spots along row 4, above a narrow dark stripe or dark sides; a tendency for a line of dark dots on each side of the venter (or ventrals dark­edged in poecilopogon ), with venters otherwise immaculate or nearly so.

There are usually fewer than 20 prediastemal maxillary teeth except in bilineatus , which has a maximum of 23, with species differences as follows 6:

5 Myers (1974: 40) failed to find apical pits in these four species, and Di­Bernardo and Lema (1987: 212) specifically mentioned their absence in T. poecilopogon .

6 The ranges in numbers of prediastemal teeth are derived from Myers (1974: 197, and subsequent unpubl. data), combined with the larger samples in Di­Bernardo and Lema (1986: 117–118; 1987: 213; 1988: 232, 234; ‘‘1990’’ [1991]: 372, 390).

T. affinis 8–18 (N 5 54) 7

T. bilineatus 18–23 (N 5 28)

T. persimilis 15–18 (N 5 18)

T. poecilopogon 13–18 (N 5 17)

The hemipenis is single, with an asulcate interspinal gap that becomes conspicuous on eversion. This gap is not nude, but bears a medial line of at least several spinules or papillae. The interspinal gap, open proximally, extends distally nearly to the calyculate tip of the hemipenis, where it terminates at an asulcate cluster of several enlarged papillae that are further differentiated in being flaplike or spinelike. Figure 9 shows these differentiated asulcate papillae on everted hemipenes of three of the four species in the group— T. affinis (fig. 9A), T. bilineatus (fig. 9B), and T. persimilis (fig. 9C). A retracted organ of the fourth species, T. poecilopogon , was said to have ‘‘relatively large’’ papillae on the asulcate side of the tip, and to be similar to that of T. affinis ( Myers, 1974: 217) .

The differentiated asulcate papillae appear to be a hemipenial synapomorphy supporting the monophyly of the Taeniophallus affinis group. Also synapomorphic is the supralabial pattern (7 labials, 2nd in loreal, 3rd–4th in orbit), which is practically invariant. These snakes otherwise are generalized small terrestrial colubrids that are ‘‘ Rhadinaea ­like’’ in most external features.

The hemipenial interspinal asulcate gap is similar to that in Echinanthera s.s., the species of which differ in most other features.

Figures

Fig. 9. Everted hemipenes of Taeniophallus s.l., in sulcate and asulcate view. A. T. affinis, MZUSP 5032, right organ 36.9. B. T. bilineatus, MZUSP 1902, left 36.3. C. T. persimilis, MZUSP 4108, left 36.7. D. T. occipitalis, MZUSP 2002, right organ in asulcate view, 37.1. (Laboratory preparations from hemipenes preserved in retracted or partially everted condition; fully everted but not necessarily completely expanded.)