Conepatus semistriatus elieceri, Molinari & Abarca-Medina & Rivas-Rodríguez, 2024

Molinari, Jesús, Abarca-Medina, María R. & Rivas-Rodríguez, Belkis A., 2024, A new subspecies of Conepatus semistriatus (Boddaert, 1784) (Mammalia, Carnivora, Mephitidae) from Venezuela, and the first known case of insular dwarfism in living skunks, Anartia (Oxford, England) 38, pp. 23-44 : 32-35

Conepatus semistriatus elieceri ssp. nov.

http://zoobank.org/urn:lsid:zoobank.org:act:3363DEF5-5EAA-4BF7-

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Margaritan Hog-nosed Skunk Zorrillo rayado margariteño

Holotype ( Figs. 2B and 5A)

An adult female (EBRG 3138), consisting of cranium, mandibles, and study skin.

Type locality

Venezuela, Estado Nueva Esparta, Margarita Island , Cerro El Tamoco, 4 km E Santa Ana, 11.07° N, 63.89° W, 400 m.

Paratypes

We designate as paratypes three specimens of unknown sex: MBUCV 5274 , from the type locality; EBRG 18983 , from Quebrada la Montaña, 12 km W Boca de Río, 10.946° N, 64.287° W, 12 m; and CVULA 9121 , from near San Francisco , 11.01° N, 64.29° W, 160 m.

Measurements of the type material

The measurements of the holotype are provided in Table 1 . The skull measurements (mm) of the paratypes (MBUCV 5274, EBRG 18983, CVULA 9121) are: basilar length, 63.4, 65.0, 62.3; condylobasal length, 71.8, 73.0, 70.6; zygomatic breadth, 46.6, 50.1, 44.0; mastoid breadth, 39.7, 40.0, 36.6; interorbital breadth, 23.5, 24.3, 23.0; postorbital breadth, 20.7, 22.5, 20.5; palatilar length, 29.3, 30.3, 28.7; post-notch length, 5.0, 3.9, 4.0; notch to canine length, 22.6, 23.3, 20.7; precanine length, 5.6, 5.1, 5.2; postpalatal length, 32.9, 33.5, 32.9; height of cranium, 25.6, 27.8, 25.2; length of maxillary toothrow, 22.1, 23.7, 22.4; width across incisors, 11.3, 12.1, 11.6; width across canines, 17.2, 19.3, 18.1; width across molars, 29.9, 30.8, 29.8; diameter of canine, 4.2, 5.1, 4.0; length of PM3, 3.6, 4.5, 3.2; length of PM4, 7.2, 8.0, 7.8; length of molar, 7.3, 7.8, 8.0; width of molar, 9.7, 10.2, 10.6; width of interpterygoid fossa, 8.2, 8.9, 9.7; length of lower carnassial, —, 10.6, 10.5; height of coronoid, 27.8, 25.0, 22.5; length of mandible, 49.1, 48.6, 44.6.

Diagnosis

Small for a South American member of the C. semistriatus group. The rostrum is relatively low (rostral angle less than 50°, see Methods) in lateral view ( Fig. 2B). On dorsal view of the cranium, the anteriormost margins of the nasal bones do not project fully over the palatal plane, leaving the anterior region of the premaxillae and the incisive and interincisive foramina fully exposed. In most specimens, the anterior opening of the infraorbital foramen is single (not divided) in at least one side of the cranium. The nasal spine is short or absent, and the nasal septum (part of the vomer bone) does not extend rearwards, thus does not form a keel, past the postpalatal shelf. The hypoglossal (condyloid) foramen is well separated from the posterior lacerate foramen.

Description

As other Venezuelan, Colombian, and Central American members of the C. semistriatus group, the holotype possesses two white dorsal stripes, joined only on the head, each of them broader anteriorly and narrower posteriorly, and with little separation between them ( Fig. 5A). The type specimen is unusual in possessing numerous dark spots on the dorsal stripes, and a fully dark tail with short hairs all along ( Fig. 5A). The hairs of the dorsal stripes are longer than those of the back. The pelage is brown and the skin is yellowish. As characteristic of Conepatus , the area around the nose is bare, the ears are much reduced, and the claws on the forefeet are long.

The cranial size ( Table 1 ) is medium for the genus: condylobasal length is more than 70 mm, and less than 77 mm. The skull is much higher in the temporal than in the frontal region. The rostrum is narrow and short in dorsal view ( Fig. 2B). In older adults, a low (usually 1–2 mm) sagittal crest is present. The zygomatic arches vary from moderately to strongly bowed upwards. The tympanic bullae are small, and not inflated. The dental formula is: incisors 3/3, canines 1/1, premolars 2/3, and molars 1/2 on each side, for a total of 32 teeth. The single upper molar is much enlarged; P1 is absent, as in all skunks; P2 is absent, as in most Conepatus . There is a distinct notch between the metacone and the hypocone of the upper molars. The lower edges of the mandibles are bowed downwards. Most specimens have a single mental foramen (few have one or two small accessory foramina near the mental foramen) on each mandible. The coronoid process has a narrow tip, and is bowed forward both anteriorly and posteriorly: these characteristics of the mandible are more marked in other Margaritan specimens than in the holotype ( Fig. 2B). In m1, the talonid is much longer than trigonid.

Comparisons ( Table 1 , Figs. 2 and 5)

We compare the new subspecies first with its geographic neighbor, and likely closest relative, then with species of Conepatus distributed from north to south in the Nearctic and Neotropical regions.

Compared to C. s. semistriatus from the Venezuelan mainland east of the Andes (this study), the new subspecies is much smaller, with no overlap in several cranial measurements. Its rostrum is proportionally shorter, narrower, and lower, with a rostral angle of less than 50°, as opposed to more than 50°. The coronoid process is narrow-tipped, and much bowed forwards, as opposed to broad tipped, and moderately bowed or straight. In the new subspecies, each mandible usually has a single mental foramen, sometimes surrounded by one or two poorly developed accessory foramina, as opposed to one mental foramen accompanied by one to four, often well-developed, accessory foramina. Little is known about the external appearance of the new subspecies, but the study skin of the holotype, which is the only one available, has two features not observed in C. s. semistriatus , namely numerous dark spots on the dorsal stripes, and a dark tail, as opposed to totally white stripes, and a tail having at least a white tip (in most cases the distal half or two-thirds are white). The tail also has shorter hairs.

Compared to C. leuconotus , the new subspecies possesses a hypoglossal foramen well separated from the posterior lacerate foramen, as opposed to confluent with it. In m1, the talonid is much longer than trigonid, as opposed to the talonid slightly longer than the trigonid. Dorsally, the pelage shows two white stripes, as opposed to a single and central white stripe.

Compared to Central American C. semistriatus , on dorsal view of the cranium, the incisive and interincisive foramina of the new subspecies are fully exposed, as opposed to partly covered by the nasals, which extend farther frontally. The precanine and postdental regions are proportionally longer with respect to the rest of the palate. The anterior opening of the infraorbital foramen is usually single, as opposed to double or triple. Each mandible usually has a single mental foramen, as opposed to one mental foramen accompanied by up to six accessory foramina. In contrast with the holotype of the new subspecies, specimens of Central American C. semistriatus possess distally white (one-third to more than one-half the length) tails.

Compared to Ecuadorian and Peruvian C. semistriatus (C. s. taxinus, and C. s. zorrino) and C. chinga (C. c. quitensis , C. c. rex ), the new subspecies is smaller. On dorsal view of the cranium, its incisive and interincisive foramina are fully exposed, as opposed to partly or totally covered by the nasals. Its postorbital region is not as narrowly constricted, its sagittal crest and nasal spine are less developed, and its upper molars and fourth upper premolars (P4) are proportionally larger. The holotype of the new subspecies has dorsal stripes that are less separated from each other than those of Ecuadorian and Peruvian specimens.

Compared to C. chinga amazonicus and southern South American members of the C. chinga -group, the new subspecies has a short or absent nasal spine with the nasal septum fully inside the nasal cavity, as opposed to a well-developed nasal spine with a nasal septum that typically (C. c. amazonicus ), or sometimes (southern South American material), continues into a keel posterior to the nasal spine. Its zygomatic arches are from moderately to strongly bowed upwards, as opposed to moderately bowed or almost straight. It has a less inflated tympanic bulla. Compared only to C. c. amazonicus , the new subspecies is smaller. Unlike the holotype of the new subspecies, C. c. amazonicus typically has a predominantly white tail. Compared only to southern South American specimens, the new subspecies is larger. On dorsal view of the cranium, its incisive and interincisive foramina are fully exposed, as opposed to partly or, more typically, covered by the nasals, which extend anteriorly causing the nasal cavity to open frontally through a comparatively small and rounded orifice. The holotype of the new subspecies has narrowly-separated dorsal stripes, as opposed to widely-separated dorsal stripes (often reduced or absent). The C. semistriatus from Venezuela, Colombia, and Central America always have well-developed dorsal stripes. This seems to be also de case of C. c. amazonicus .

Distribution ( Fig. 1)

Endemic to Margarita Island, Venezuela. Occurring in both geographic subdivisions (Macanao Peninsula, Paraguachoa) of the island.

Etymology

The epithet elieceri, a masculine noun in the genitive case, honors the Venezuelan researcher Eliécer E. Gutiérrez, in recognition of his outstanding contributions to Neotropical mammalogy.