Abbottella (Abbottella) diadema, Watters, G. Thomas, 2013

Watters, G. Thomas, 2013, New taxa and distributional notes on Abbottella and related taxa (Gastropoda: Littorinoidea: Annulariidae), Zootaxa 3646 (1), pp. 1-22 : 4-6

Abbottella (Abbottella) diadema new species

Figures 1 F–J, 5 P, 7 B

Type material. UF 456814, holotype; length, 5.1 mm; width, 6.0 mm. UF 456815, 5 paratypes, from the type locality.

Type locality. Dominican Republic, Samaná Province, Cabo Cabrón, at 280 m. ca. 19.34° N, - 69.25° W.

Other material examined. UF 215985, 44 specimens, from the type locality (see Remarks).

Distribution and habitat. Known only from the type locality. This region is on the northeastern tip of the Samaná Peninsula; it is part of the Sierra de Samaná of the Cordillera Septentrional and is locally known as Loma Travesada, which name appears on the original label. Specimens were found under limestone boulders on a slope in a virgin rain forest. This is a very isolated area of the country.

Description. Shell very small (largest specimen, holotype, 5.1 mm total length including peristome x 6.0 mm total width including peristome; smallest specimen, 3.1 mm total length x 3.7 mm total width), turbinate, whorls adnate except just before lip. Umbilicus wide, ca. 33% of total width, open to earliest whorls. Protoconch of ca. 1.5 minutely pustulose whorls but demarcation between protoconch and teleoconch not well-defined. Teleoconch of 2.5–2.75 whorls. Axial sculpture of numerous, crowded, low lamellae, slightly wider on spiral keels. Sculpture is more widely spaced on earliest whorls. Spiral sculpture present only as keels; 1–3 keels between the suture and the periphery; one on the periphery; one bounding the umbilicus; 0–3 in the umbilicus. The axial sculpture on the keels forms a very dense, finely serrate edge. On the whole the sculpture has a frosted aspect. Suture narrowly channeled, serrate. Aperture double, circular (2.7 mm maximum width in holotype), solute from final whorl. Inner lip smooth, narrowly exserted. Outer lip slightly expanded, slightly narrower facing the umbilicus, consisting of numerous fused lamellae, with two auricles 180° apart. Axial sculpture does not extend onto outer lip. Shell uniformly dirty white/tan or patterned with vague brown, spiral bands, most apparent on both sides of outer lip. Operculum multispiral with an oblique, erect, calcareous lamella.

Variation in specimens. 50 specimens seen. The degree of coloration varies from uniformly white to banded with brown. The number of spiral keels (3–7) varies but there is always a keel between the suture and periphery, at the periphery, and bounding the umbilicus. There is a tendency for larger specimens to have more spiral cords.

Comparison with other species. This species displays so many unique characteristics that it should likely be placed in its own genus. It is one of the smallest Abbottella yet found and has the fewest number of whorls. The curious combination of tightly packed axial sculpture and spiral cords is unlike any other annulariid.

Remarks. The 44 additional specimens range from fresh dead to weathered specimens but all are broken in the same manner as A. calliotropis (see Remarks there) by an unidentified predator ( Figure 5 P).

Etymology. Gr. diadem, headband, crown.

Figures

FIGURE 1. A – E. Abbottella (Abbottella) calliotropis new species. A – C. Holotype (UF 456810), 7.5 mm width. D. Paratype (UF 216131), 6.8 mm width. E. Paratype (UF 216131), 7.0 mm width. F – J. Abbottella (Abbottella) diadema new species. F – H. Holotype (UF 456814), 6.0 mm width. I. Paratype (UF 456815), 4.6 mm width. J. Paratype (UF 456815), 3.7 mm width. K – O. Abbottella (Abbottella) dichroa new species. K – M. Holotype (UF 456801), 9.9 mm width. N. Paratype (UF 216112), 8.8 mm width. O. Paratype (UF 216112), 9.4 mm width. P – T. Abbottella (Abbottella) nitens new species. P – R. Holotype (UF 456806), 7.8 mm width. Note pseudoscorpion web in umbilicus. S. Paratype (UF 456808), 8.3 mm width. T. Abbottella (Abbottella) mellosa Watters & Duffy, 2010. Holotype (UF 420729), 7.9 mm width. U – Y. Abbottella (Abbottella) tenebrosa new species. U – W. Holotype (UF 456796), 8.9 mm width. X. Paratype (OSUM 37271), 8.6 mm width. Y. Paratype (OSUM 37271), 8.3 mm width. Z – CC. Abbottella (Gundlachtudora) paradoxa new species. Z – BB. Holotype (UF 456812), 9.0 mm width. CC. Paratype (UF 456813), 8.9 mm width. DD. Abbottella (Gundlachtudora) bombardopolensis Bartsch, 1946. UF 33037, 7.0 mm width.

FIGURE 5. A – F. Rolleia haitensis Bartsch, 1946. A – C. Holotype (USNM 504088), 12.0 mm width. Photo courtesy of USNM. D. UF 32777, 15.4 mm width. E. UF 32777, 13.7 mm width. F. UF 32863, 13.2 mm width. G – N. Rolleia oberi Watters & Duffy, 2010. G – I. Holotype (UF 434775), 10.3 mm width. J. UF 236228, 10.2 mm width. K. UF 216195, 11.0 mm width. L. UF 216195, 11.5 mm width. M. UF 216195, 10.7 mm width. N. UF 216195, 11.3 mm width. O. Abbottella (Abbottella) calliotropis new species. UF 216131, 7.1 mm width. Note predation damage. P. Abbottella (Abbottella) diadema new species. UF 215985, 5.0 mm width. Note predation damage. Q. Abbottella (Abbottella) dichroa new species. UF 216112, 8.3 mm width. Note predation damage. R, S. Abbottella (Abbottella) nitens new species. R. UF 216167, 7.9 mm width. Note predation damage. S. Holotype (UF 456806), 7.8 mm width. Note predation damage.