Echinanthera, 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 : 16-18

ECHINANTHERA COPE

This is a well­defined genus, at least in the strict sense when considering the closest relatives of the type species. In this context, six species seem assignable: Echinanthera amoena , E. cephalomaculata , E. cephalostriata , E. cyanopleura (type species), E. melanostigma , and E. undulata . Two of these were recently described by Marcos Di­Bernardo, the principal authority on the genus: he named the outlying E. cephalomaculata based on two specimens from Estado Alagoas in northeastern Brazil ( Di­Bernardo, 1994), and he teased out the new E. cephalostriata from E. cyanopleura , with which it had been confused ( Di­Bernardo, 1996).

These are medium­sized terrestrial snakes, all probably exceeding 600 mm total length. 8 Based on relatively few measurements (Myers, unpubl.; Di­Bernardo, 1996: 123), maximum total lengths reach or exceed 700 mm in amoena , cephalostriata , and undulata and exceed 800 mm in cyanopleura and melanostigma . A female melanostigma (UMMZ 63030) was measured at 882 mm total length, and meter­long Echinanthera seem likely.

There are 17 dorsal scale rows without reduction. Apical scale ‘‘pits’’ are present on some specimens of at least five species. 9 These scale organs are either paired or single (if single, the pit is an apparent remnant of a pair, being offset from the median). There normally are 8 supralabials (rarely 7 or 9), usually with 2nd–3rd or 2nd only touching the loreal and 3rd–5th (less commonly 4th– 5th) in the orbit. This differs significantly from the Taeniophallus affinis group (7 supralabials, 3rd–4th in orbit).

The color pattern includes a strongly undulating middorsal stripe in cephalomaculata and undulata and in at least some specimens of cyanopleura (e.g., the syntypes), but this stripe seems to have been degraded to somisolated spots in cephalostriata ( Di­Bernardo, 1996: fig. 1) and melanostigma , and it is essentially lost in amoena . A line of whitish dashes or small spots along rows 3 and/or 4. Normally dark dots on the ends of the ventrals. Specimens of all species except amoena and cephalomaculata have conspicuous gray or blackish crossbanding over much of the belly; variation in the ventral crossbands includes their ontogenetic development, at least in undulata ; a few traces of crossbanding are retained in some specimens of amoena .

7 There is variation in numbers of prediastemal teeth in most snakes, with the difference between extreme counts usually seeming to be in the range of perhaps 2– 5 teeth for many South American colubrids (e.g., Myers, 1974: 29, table 1). The large variation in Taeniophallus affinis is therefore noteworthy.

8 The female holotype of Echinanthera cephalomaculata measured 561 mm total length, but only two specimens of this species are known ( Di­Bernardo, 1994).

Myers (1974: 29, 199) noted that two affinis specimens with the maxillary formula 10 1 2 had all the teeth short and thick, compared with relatively longer, more slender teeth in four snakes with the formulae 14 1 2– 18 1 2. Since then, however, an additional specimen with the formula 10 1 2 was coded with seemingly normal teeth. This variation is not explained, although Di­ Bernardo and Lema (1988: 232) showed that geographic variation is involved in total counts. Assuming that sibling species are not being confused, one might expect the existence of geographic shifts in availability of major prey types.

9 Apical pits were not mentioned in Di­Bernardo’s (1994) description of Echinanthera cephalomaculata . Myers has coded presence of these scale organs in specimens of E. amoena , E. cyanopleura , E. melanostigma , and E. undulata , and Di­Bernardo (1996: 123) reported small paired (rarely single) apical pits in E. cephalostriata . Some specimens seem to lack these structures completely. They are constant and easily seen in some genera, but a difficult character in such groups as Echinanthera . See Myers (1974: 40–41) for discussion.

There normally are more than 25 prediastemal maxillary teeth, with variation as follows 10:

E. amoena 25–28 (N 5 4)

E. cephalomaculata 27–28 (N 5 2) E. cephalostriata 24–32 (x 5 27.8, N 5 35) E. cyanopleura 27–29 (N 5 2)

E. melanostigma 27–32 (N 5 6)

E. undulata 29–32 (N 5 12)

The strongly calyculate hemipenis has an interspinal asulcate gap that becomes pronounced upon eversion. This gap is not necessarily nude as sometimes stated, but usually contains a median line of tiny spines or spinelike papillae along part of its length (fig. 10). The calyces are papillate, with the papillae becoming either slightly or markedly larger, even spinulate on the asulcate side above the upper end of the interspinal gap— but they do not form a differentiated cluster. There is no small asulcate cluster of abruptly enlarged, strongly differentiated papillae such as in the affinis group of Taeniophallus (compare fig. 10 with fig. 9A–C). 11

The monophyly of Echinanthera s.s. is supported by the derived condition of a large number of prediastemal maxillary teeth (25– 32)—an unusually high number among most dipsadine and xenodontine colubrids. An undulating middorsal stripe and ventral crossbanding also may be synapomorphic for Echinanthera , with apomorphic degradation in a few species. Other characters that distinguish Echinanthera s.s from the Taeniophallus affinis group include scale pits and generally larger size of the former, and the apomorphic supralabial pattern in the latter.