Typhlops hectus Thomas 1974
Creators: name: Thomas, Richard
name: Hedges, Blair
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Typhlopidae
Typhlops
Typhlops hectus

description: Typhlops hectus Thomas, 1974 (Figs. 3 A, 4A)
Holotype: MCZ 81149, collected at Martineau, ca. 9 km (airline) W Jérémie, Dépt. de La Grande Anse, Haiti.
Diagnosis: A moderate sized, 20­scale­row species of Typhlops, having moderate middorsal scale counts (284–328) and a low frequency of posterior reduction. Typhlops hectus differs from the other 20­row species with ~300 middorsal scales in its clavate rostral shape in which the rostral broadens posteriorly, becoming broadly rounded at the tip (Fig. 3 A). The anterior projection of the preocular has a relatively small angle and sharp apex. The posterior nasal­preocular suture curves gradually ventrad. The suture between the preocular and the 3rd infralabial is relatively short. The edges of the posterior nasals flanking the rostral tend to bowed out. The pigmentation is variable but most populations are relatively lightly pigmented, ranging from medium to pale brown or tan, often with irregularities or mottling and a pale snout. The hemipenes are trumpet­shaped.
Description: Rostral in dorsal aspect narrow anteriorly, widening toward the tip (RW1/RL1 0.45–0.64), preocular angle 42–72o, with an apex that is typically relatively sharp (low apical diameter) to more broadly rounded but without breaks interrupting its curvature (apical diameter 0.14–0.57 mm); lower portion of preocular contacting only the 3rd of the upper labials. The angled anteriormost point is so pronounced that in a few animals a suture actually extends partly or all the way to the naris, resulting, in the latter case, in a divided anterior nasal. Ocular length is approximately 1/2 height; sinuosity 0.23–0.1. The rostronasal pattern is parenthesis­like to parallel or slightly divergent with the dorsal limb of the posterior nasal typically having a slight bend rather than being smoothly curved, the bend being often most visible in the glandular edges of the scale papilla. There are two postoculars (cycloid). The first parietal is standard, spanning two scale rows, occasionally narrower, spanning slightly more than one scale row. The second parietal is present and equal in size to first or absent. TL 135–218 (= 174, N = 75) mm, excluding two 116 mm juveniles. (10) TL/TA: males 20– 24, females 28–44. TL/MBD 31–46. Middorsal scales 284–328 (= 306, N = 75).
In Tiburon Peninsula specimens of T. hectus the modal number of initial scale rows is 20 with 9% having 22 or 21 and reducing to 20 before midbody; reduction below 20 scale rows occurs on the posterior body (73– 94% of TL) in 42% of the specimens with about half of these (19%) reducing only to 19 rows. The North Island T. hectus are similar in having an initial scale row number of 20 (30% have 22 or 21 rows for a short distance anteriorly), but all reduce to 18 scale rows farther anteriorly than Tiburon Peninsula T. hectus, at 46– 86% of TL, or somewhat beyond midbody on the average. Pigmentation is generally light (brown or tan) and fades ventrally with some dropping out of pigmented scales. The rostral and adjacent upper wings of the posterior nasals are largely unpigmented, making the snout distinctively pale. The population of T. hectus around Morne Salagnac, west of Miragoane, Haiti (the easternmost samples on the Tiburon Peninsula; Fig. 5), contrasts with other populations in being very heavily and extensively pigmented. The pigmentation fades ventrally but pigmented scales extend irregularly onto the venter, often completely across it. The North Island populations are somewhat more heavily pigmented than those of the distal Tiburon Peninsula. Hemipenes are trumpet­shaped and flat apically. The sulcus spermaticus enters the organ medially, spirals posteriorly and laterally for 1/4 turn, proceeding to the distal region.
Distribution: The distribution of T. hectus sensu stricto extends from the distal Tiburon Peninsula east to the vicinity of Miragoane and Île la Gonâve. The associated specimens of T. hectus occur on the North Island of Hispaniola from the vicinity of Lascahobas, Haiti, in the west to the southern slopes of the Cordillera Central, north of San Juan de la Maguana, Dominican Republic, in the east (Fig. 5).
Specimens examined: Specimens of Typhlops hectus in the Albert Schwartz Field Series (ASFS) listed by Thomas (1974) are presently deposited in the University of Kansas Museum of Natural History (KU) and were re­examined for this paper; the specimens of geographic sample “a” (Thomas, 1974) are herein designated as paratypes of two species described below. ASFS V9821 (KU 269825), examined by Thomas (1974) is one of the associated specimens of a new species described below. Additional specimens of Typhlops hectus are all from Haiti. Dépt. du Sud: USNM 564793–795, 1.5 km N Ducis; KU 288519, 5.1 km W Anse a Veau; Dépt. de la Grande­Anse: USNM 564792, ca. 3 km N Bois Sec, 360 m; USNM 564796, 3.6 km S Baradères; ASFS V44239, V44427, 18.8 km N Cavaillon; ASFS V44499 –515, 20.6 km N Cavaillon; KU 288520–525, 288542–562, Caye Morbette, 5.1 km SW Paillant, 727 m; KU 288523, Paillant, 575 m; KU 288534–541, 1.1 km SW Paillant, 606 m; KU 288526–532, Dimisaine, 1.6 km SW St. Michel du Sud; KU 288563, Ile de la Gonâve, Haiti. As noted above, this list does not include “associated specimens” of T. hectus, sensu stricto, from the North Island of Hispaniola.
Comments: An unusual excess of females is present in several large samples of this species. For example, all 32 specimens examined from the North Island are females, with the possible exception of a very small individual. All 23 snakes that were sexed from the region of the type locality in the western part of the Tiburon peninsula were also females. Nearly all (102 out of 107) snakes from Fond de Nègres (Dépt. de la Grande­ Anse) were females, although that percentage was lower (73%) in a nearby sample of 37 snakes from the Paillant region. In other areas, such as near Camp Perrin, the sex ratio was more even. Whether this indicates parthenogenesis, facultative parthenogenesis, or sexual dimorphism in habits remains to be determined.
The first of the new species occurs on the northern slopes of the Massif de la Selle and Sierra de Baoruco. It may be known as
description: Published as part of Thomas, Richard & Hedges, Blair, 2007, Eleven new species of snakes of the genus Typhlops (Serpentes: Typhlopidae) from Hispaniola and Cuba, pp. 1-26 in Zootaxa 1400 on pages 4-7, DOI: 10.5281/zenodo.175414