Diplopoma osberti ( Tristram, 1861 )

Watters, G. Thomas, 2014, A revision of the Annulariidae of Central America (Gastropoda: Littorinoidea), Zootaxa 3878 (4), pp. 301-350 : 334-335

Diplopoma osberti ( Tristram, 1861)

Figure 8 F–K, 12 B, 13 D, K

Type material. “ Figured type ” JDC, fide Chevallier, 1965: 28, but not in MNHN database; USNM 515464 (3), paratypes.

Type locality. Not stated but Guatemala implied from title of publication.

Type figured. Chevallier (1965) mentions figured type as Fischer & Crosse, 1890: pl. 42, figs. 13, 13a, 13b.

Cresonymy.

Adamsiella osberti Tristram, 1861: 232 ; Pfeiffer, 1865: 120; Bland, 1866: 60; Pfeiffer, 1876: 166; Fischer & Crosse, 1888: 175; Fischer & Crosse, 1890: 178 –179, 182, pl. 42, figs. 13, 13a, 13b; Chevallier, 1965: 28; Watters, 2006: 386 –387.

Choanopoma osberti ( Tristram, 1861) . Martens, 1890: 14, 16.

Licina (Choanopomops) osberti ( Tristram, 1861) . Baker, 1928: 48.

Annularia (Annularis [sic]) rigidula “Morelet” Haas, 1949. Solem, 1961: 196 [in synonymy of Adamsiella osberti Tristram, 1861 ].

Choanopoma (Choanopomops) osberti (Tristam [sic], 1861). Solem, 1961: 195 –197, pl. 10, fig. 2, pl. 12, fig. 24b, map 1.

Parachondrops osberti ( Tristram, 1861) . Watters, 2006: 48, 386–387.

Choanopoma (Choanopomops) osberti ( Tristram, 1861) . Thompson, 2011: 46, 280.

Distribution and habitat. Despite numerous collections made across the general region, this species is known only from the karstic vicinity of [San Agustín] Lanquín at 300–350 m altitude in Alta Verapaz Department of Guatemala in the northern foothills of the Sierra de los Cuchumatanes, the highest non-volcanic mountain range in Central America. Solem (1961) listed Sacatepequez Department as well but this is unlikely. That locality is two mountain ranges to the south across the Sierra de los Cuchumatanes and Sierra Madres and there is no indication this species occurs at those altitudes and on granitic ranges. The habitat of this species is similar to D. rigidulum —under rocks and among scree in karstic areas, probably in caves in the Grutas de Lanquín system. Locally abundant.

Conservation. None of the localities lie within the adjacent Parque nacional Grutas de Lanquín. But this park protects a large cave system that very likely harbors this species.

Other material (specimens examined: 194). Guatemala. Alta Verapaz Department: UF 190061 (3), 0.5 km W of Lanquín, 300 m; UF 190077 (53), 2.0 km WNW of Lanquín; UF 190089 (132), 4.0 km W of Lanquín, 330 m; UF 190117 (3), UF 190118 (1), 8.0 km SE of Lanquín, 350 m; GTW 16017a (7), Semuc Champey.

Description. Shell conical, high-spired, thin, last 1/3 – 1/2 of whorl solute. Smallest adult specimen seen 9.5 mm in length, largest 11.4 mm, average 10.4 mm (decollate). Protoconch lost in adult, unknown. Teleoconch of 4 – 4.5 rounded whorls. Umbilicus narrow, open. Spiral sculpture absent. Axial sculpture of numerous fine, nearly obsolete, distantly spaced lamellae. Suture strongly indented, not serrated. Aperture nearly circular. Inner lip smooth, narrowly exserted. Outer lip lamellate, reflected perpendicular to whorl, more or less evenly expanded, somewhat narrower facing umbilicus, auriculate posteriorly, solute from previous whorl. Base color dingy white to purplish. Patterned with ca. 4 – 5 diffuse brown bands broken into spots, bands do not continue over adapertural face of peristome, spots visible inside aperture; peristome white, occasionally tinged with purple. Operculum multispiral, circular, with an erect calcareous lamella. Radula and anatomy unknown.

Animal pale cream or tan (fig. 13 D); middle portion of antennae pale yellow, tips abruptly darker; area between bases of antennae pale purplish brown, diffuse. Eyes black.

Variation in specimens. Except for the strength of the color pattern, there is little variation in the few specimens seen. The specimens from Semuc Champey are particularly elongate and solute.

Comparison with other species. Only D. rigidulum superficially resembles D. osberti but it is easily distinguished by its coarse, lamellate axial sculpture. No other Central American species has the combination of obsolete sculpture and solute final whorl seen in D. osberti .

Remarks. Solem (1961) suggested that D. rigidulum ( Morelet, 1851) may be the lowland form of D. osberti . Although their ranges narrowly overlap, they remain distinguishable in these areas. I believe D. osberti is a very narrow endemic to the karst region of the Grutas de Lanquín and is distinct from D. rigidulum . Both species occur in this area. Watters (2006) placed both species in Parachondrops , but the absence of tufts and the solute final whorl suggest it is better placed in Diplopoma .

Original description (translated here from Latin). “Shell narrowly perforate, turreted, entire, pale yellowish-brown, with crowded longitudinal striations, decorated with five perhaps six interrupted red bands; spire regularly turreted, apex a good part apart; six whorls, last solute; aperture vertical, round; peristome double, inner one brown, narrowly expanded, outer expanded, horizontally extensive, red, upper angle produced; penultimate whorl, slightly cut.” 12 mm.

Etymology. Osbert Salvin (1835–1898), English naturalist, ornithologist, and herpetologist, co-author of Biologia Centrali-Americanum (1879–1915).

Figures

FIGURE 8 A – E. Paradoxipoma enigmaticum new species. A – B. UF 479320, holotype, 9.4 mm. C. UF 479320, paratype, 8.3 mm. D. UF 479320, paratype, 7.7 mm. E. UF 479322, paratype, 8.4 mm, detail of operculum. FIGURE 8 F – K. Diplopoma osberti (Tristram, 1861). F. Fischer & Crosse, 1890: pl. 42, figs. 13, 13 a, 13 b. G. UF 190089, 11.4 mm. H. UF 190089, 9.8 mm. I. UF 190089, 9.5 mm. J. UF 190061, 10.9 mm. K. GTW 16017 a, 10.1 mm. FIGURE 8 L – W. Diplopoma rigidulum (Morelet, 1851). L. NHMUK 1893.2. 4.705, syntype, ca. 12 mm, photo courtesy J. Ablett (NHMUK). M – N. UF 155790, 8.8 mm. O. GTW 8731 a, 9.7 mm. P. Grego coll., 9.5 mm. Q. GTW 8713 c, 9.5 mm. R. GTW 8731 e, 9.1 mm. S. UF 15813, 6.4 mm. T. GTW 8713 g, 9.4 mm. U. UF 146240, 9.3 mm. V. UF 135055, 8.6 mm. W. UF 207341, 9.6 mm.