Dendrophidion nuchale

Cadle, John E. & Savage, Jay M., 2012, Systematics of the Dendrophidion nuchale complex (Serpentes: Colubridae) with the description of a new species from Central America, Zootaxa 3513, pp. 1-50 : 39-40

Dendrophidion nuchale (TCWC 59022. Figs. 26–27 , right hemipenis)

Total length about 24 mm. A narrow basal portion of the hemipenis is followed by a bulbous spinose section, which is delimited distally by a constriction. Distal to the constriction the hemipenis again expands. The apex is slightly bilobed. The sulcus spermaticus is simple, centrolineal, extends nearly to the center of the apical surface, and has a flared tip.

Base with widely scattered minute spines. On the sulcate side a pair of enormous spines (enlarged sulcate spines) demarcates the proximal edge of the enlarged spine array; the enlarged sulcate spine on the right side of the sulcus is closer to the sulcus and more proximally placed than the one on the left. On the asulcate side of the organ is a pair of enlarged asulcate spines; these are smaller than the enlarged sulcate spines but are larger than most other spines on the organ. Distal to the enlarged sulcate and asulcate spines are much smaller spines in two or three irregular rows completely around the organ; proximal spines in these rows are slightly larger than more distal spines. These small spines are immediately followed by a row of 13 much larger spines encircling the organ (spinose annulus). Spines in the annulus are smaller than the enlarged sulcate spines but approach or slightly exceed the size of the enlarged asulcate spines. Individual spines on the hemipenis are thick, short, and with a slightly curved spike at the tip. The total number of spines on the right organ is 57 (44 spines including enlarged sulcate and asulcate spines + 13 spines in the annulus). The left hemipenis of this specimen has a total of 52 spines (40 spines including the enlarged sulcate and asulcate spines + 12 spines in the annulus).

Distal to the spines are flounces and calyces. These structures are more flouncelike proximally and calyxlike distally, although longitudinal and oblique connections occur even between the most proximal pair of transverse ridges. About four to five rows of flounces/calyces are adjacent to the sulcus spermaticus, three rows on the asulcate side. Walls of the calyces/flounces gradually become lower distally (i.e., the calyces become shallower). The edges of the proximal calyces/flounces are strongly crenulated; edges of the last one or two rows are smoothedged on the sulcate side (and to a lesser extent on the asulcate side). Calyces peter out at the lateral edges of the apex (before the turn to the apical tip). The tip of the apex is mostly nude but with some thickened ridges (seemingly remnants of calyx walls) ( Fig. 27 ). These ridges are concentrated on the asulcate side of the apex.

Most of the flounces/calyces are spinulate, with the spinules having an embedded portion and tips that occupy the points of the crenulated edges. Spinules are absent or greatly reduced in the most distal rows of calyces, especially on the sulcate side. Spinules throughout are most strongly developed in the transverse ridges (flounces), with fewer in the longitudinal connections.

Variation and remarks. We examined only one other hemipenis of Dendrophidion nuchale in detail, the manually everted organ of UMMZ 142679 (the organ had been preserved with the base partially everted). Its morphology is very similar to that of TCWC 59022 but the spines (particularly those between the enlarged sulcate spines and the spinose annulus) are larger compared to the size of the hemipenis than in TCWC 59022. Spine form varies considerably in D. percarinatum and related species ( Cadle 2012b) and may do so in other species that have been less studied in this regard. The spinose annulus of UMMZ 142679 has 12 spines. Four retracted hemipenes of D. nuchale we examined extended to the suture between subcaudals 7 and 8 (1), the proximal portion of subcaudal 8 (1), or the suture between subcaudals 8 and 9 (2).

Figures

FIGURE 26. Everted hemipenis of Dendrophidion nuchale in sulcate and asulcate views (TCWC 59022, Aragua province, Venezuela).

FIGURE 27. Hemipenis of Dendrophidion nuchale, oblique apical view (TCWC 59022). Sulcus spermaticus is the deep furrow in the center of the photograph.