systematics of snakes of the dipsas oreas complex - BioOne

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86 Bulletin Museum of Comparative Zoology, Vol. 158, No. 3 well-developed papillate calyces. However, the proximal papillae, especially those adjacent to the fork of the sulcus spermaticus and those fringing the overhang, have mineralized tips. A very large (8 mm long) nude pocket extends from the base of the organ to the battery of spines; its distal end is nestled within the proximal spines of the battery. The pocket is on the dorsal surface of the inverted organ (the lateral surface of the everted organ relative to the sulcus spermaticus). The pocket has a large lobe on its absulcate edge and a smaller lobe on its sulcate edge; these lobes also bear minute scattered spines. The asulcate side of the organ (medial side of the inverted organ) bears 3 enlarged spines in a transverse row, which are separated by a gap (ornamented with minute spines) from the battery of spines on the midsection. The hemipenis of Dipsas ellipsifera is similar in many details to hemipenes of other snakes of the tribe Dipsadini that have been described (review in Cadle and Myers, 2003: 14–15). Features common to hemipenes of the Dipsadini include welldeveloped papillate calyces on the capitulum, an encircling battery of enlarged spines on the midsection, a relatively unornamented base, and a very large nude pocket proximally on either the asulcate or lateral surface of the organ. The nude pocket in D. ellipsifera is exceptionally long, 44% of the length of the organ. In other species examined by Cadle and Myers (2003: 15) the pocket was approximately 33% of the length of the organ. However, observations in Cadle and Myers (2003) were based on everted organs and it is not possible to know the relative proportions of the nude pocket in the everted hemipenis of D. ellipsifera because hemipenial tissue expands differentially upon eversion (see Myers and Cadle, 2003). The proximally divided retractor muscle in D. ellipsifera suggests that its everted hemipenis may be somewhat more bilobed than everted hemipenes of either D. elegans or D. oreas described later herein. The degree of bilobation apparently varies among species of Dipsas (Cadle and Myers, 2003: 14–15). Distribution and Natural History Dipsas ellipsifera is known only from the valley of the Río Mira in extreme northwestern Ecuador (Fig. 8). All reported specimens are from Imbabura Province; the Río Mira divides Imbabura from Carchi Province, and the species may also occur in the latter province. Elevations for the two localities for which specimens were examined in this study are 2,000 and 2,211 m, but Orcés and Almendáriz (1987) reported an elevational range of 572–2,600 m for this species (see Specimens Examined and Locality Records). Several specimens collected by Philip Hershkovitz (UMMZ 83697–700) were obtained in June and August, but most specimens are not accompanied by specific collection dates. The type locality of Dipsas ellipsifera, Ibarra, lies at 2,211 m elevation in a dry rain shadow valley of the western Andes. Rosenberg (quoted in Hartert, 1898) described the vicinity of Ibarra at the time the syntypes were collected as ‘‘. . . open, and for the most part cultivated,’’ seemingly quite different from a nearby locality at a lower elevation to the west, Paramba (Hacienda Paramba; Paynter, 1993), which Rosenberg described as ‘‘densely forested.’’ Orcés and Almendáriz (1987: 138) stated the following concerning localities for D. ellipsifera: ‘‘. . . [the localities] are found in the subtropical and temperate zones. The region in question is for the most part semiarid with shrubby vegetation; in a few cases epiphytic and parasitic plants are present. The temperature varies from 18 to 22 C and the precipitation from 500 to 1,000 mm.’’ Lita, the most western locality and the lowest elevation (572 m) from which D. ellipsifera has been recorded (Orcés and Almendáriz, 1987), lies in the region of very humid lowland rain forest characteristic of northwestern Ecuador. Because Peters (1960a) confused some
Dipsas oreas Complex in Ecuador and Peru • Cadle 87 Figure 8. Locality records for Dipsas ellipsifera, D. elegans, and D. oreas in western Ecuador and extreme northern Peru. See Figure 23 for other known Peruvian localities for D. oreas. A few symbols for D. elegans and D. oreas represent pairs of contiguous localities; otherwise, all localities considered reliable are plotted (see text and list of specimens and localities). Numbered localities. Dipsas ellipsifera: (1) Lita (Orcés and Almendáriz, 1987); (2) Chachimbiro (Orcés and Almendáriz, 1987); (3) Pimampiro; (4) Ibarra (type locality). Dipsas elegans: (5) Peñaherrera; (6) Nanegal Grande and Pacto; (7) Río Saloya; (8) Santo Domingo de los Colorados; (9) Perucho (Orcés and Almendáriz, 1987); (10) El Quinché (Orcés and Almendáriz, 1987); (11) Cumbayá and Tumbaco (Orcés and Almendáriz, 1987); (12) Mindo (north) and Chiriboga (south; Orcés and Almendáriz, 1987); (13) Corazón; (14) Pallatanga. Dipsas oreas: (15) Guayaquil; (16) Huigra/Río Chiguancay and Río Chanchan valley; (17) Alausí (Despax, 1911); (18) Velacruz; (19) Loja; (20) Río Catamayo; (21) Ayabaca (Peru); (22) Cerro Aypate (Peru).
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systematics of snakes of the dipsas oreas complex - BioOne

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