Crenilabium birmani, Simone, 2006

Simone, Luiz Ricardo L., 2006, A New Species Of The Genus Crenilabium (Mollusca, Heterobranchia, Acteonidae) From Brazil, Papéis Avulsos de Zoologia (São Paulo) 46 (7), pp. 67-71 : 68-70

Crenilabium birmani new species

( Figs. 1-12 )

Types: Holotype MZSP 63161 . Paratypes: BRAZIL; Rio de Janeiro; off São Tomé Cape , 21°42’S 40°15’W, 53 m depth, MZSP 63162 , 1 shell (R.V. “ W. Besnard ” sta. Macaé 11, 23/ii/1992) ; 22°18’52.95”S 40°11’58.95”W, 190-200 m depth, MNRJ 10703 , 9 shells (sta. P47; R.V. Astrogaroupa col. 18/xii/2004) . Rio Grande do Sul; off Rio Grande , 33°39’S 51°07’W, 200 m depth, MZSP 63163 , 1 shell (R.V. “ W. Besnard ” sta. 1891; viii/1972) .

Type locality: BRAZIL; São Paulo; off Ubatuba , 23°46’S 44°51’W, 55 m depth (R.V. “ W. Besnard ” sta. 1624; 16/xii/1971) .

Diagnosis: Shell with spire as long as aperture. Suture simple or scaled, deep. Inner lip simple; inferior region of aperture rounded or weakly bended, lacking folds.

Description

Shell ( Figs. 1-9 ): Bulloid, antero-posteriorly elongated; maximum size 8 mm; approximately 2.5 longer than wide. Wall relatively thick. Color white or yellowish white. Protoconch mammillated, of one whorl; separation with teleoconch marked by narrow orthocline furrow ( Figs. 2, 3 , 9 ). Teleoconch with up to 4.5 whorls, weakly convex, profile weakly rounded (almost straight). Suture marked by shallow, concavity and low Distribution ( Fig. 12 ): From Rio de Janeiro (off São Thomé Cape) to north coast of São Paulo (off Ubatuba); also off Rio Grande, RS.

Habitat: Sandy bottoms; 53-200 m depth.

Material examined: Types.

Etymology: The specific epithet is in honor of the discoverer of the species, the physician and conchologist Adolpho Birman, from São Paulo, SP. Brazil.

and relatively wide, smooth furrow ( Figs. 1, 2, 3 ); or deep furrow, with external edge away from superior surface of each whorl, similar to a scale turned superiorly ( Figs. 4, 5 , 6-9 ). Surface smooth, opaque, about 10 shallow, narrow spiral furrows, distributed rather irregularly; a narrow, spiral line located at certain distance from subsutural area. Last whorl with spiral furrows gradually becoming slightly deeper and close with each other towards umbilical area ( Figs. 1, 5 , 6, 7 ); about 15 in inferior half. Umbilicus absent. Aperture with about half of total length, antero-posteriorly elongated; superior end pointed, inferior (siphonal) region rounded ( Figs. 1, 5 , 6, 7 ). Inner lip concave; superior half to 2/3 convex, rounded, lacking callus; inferior half or 1/3 rounded, concave, with thick edge; between both regions of inner lip a strong notch in some specimens ( Fig. 5 ). Outer lip simple, with cutting edge, subterminally thickened.

Measurements (respectively length and width in mm): Holotype: 8.3 by 3.1; MZSP 63162 (M11): 7.1 by 2.8; MZSP 63163: 7.6 by 2.9; MNRJ 10703 #1: 7.6 by 3.2; #2: 7.4 by 2.9.

Figures

FIGURE 12. Map of distribution of Crenilabium birmani (the symbols are slightly away from its actual place); star = specimen with simpler suture; lozenge = specimens with scaled suture.

FIGURES 1-5. Crenilabium birmani shells in SEM: 1-3) holotype, 1) frontal view, length = 8.3 mm; 2) spire, frontal-slightly oblique view, scale = 0.5 mm; 3) detail of apex, profile, scale = 0.1 mm; 4-5) MZSP 63163 paratype; 4) detail of spire, frontal-slightly oblique view, scale = 0.5 mm; 5) frontal view, length = 7.6 mm.

FIGURES 5-9. Crenilabium birmani shell of paratypes MNRJ 10703:6-8) frontal, right and dorsal views of larger specimen, length = 6.8 mm; 9) detail of apex in profile of a young specimen, scale = 0.25 mm; 10-11) Rictaxis punctocaelatus holotype USNM 14914 (courtesy of Ellen Strong, Smithsonian Institution); frontal and dorsal views; length = 4.9 mm.