Cerithiella pernambucoensis, De, Silvio Felipe B. & De, José Carlos N., 2007

De, Silvio Felipe B. & De, José Carlos N., 2007, Two new species of Cerithiella (Apogastropoda: Cerithiopsidae) for the continental slope of Pernambuco (northeast Brazil), Zootaxa 1441, pp. 63-68 : 64-66

Cerithiella pernambucoensis n. sp.

( Figures 1–9 )

Type material: Holotype, MNRJ 10834 [length: 13.3 mm; width: 2.6 mm]; 1 paratype, MNRJ 10836 [length: 16.1 mm; width: 2.6 mm]; 4 paratypes, MZSP 80484; 4 paratypes, MORG 50.690; 3 paratypes, ANSP 413609; 3 paratypes, MNRJ 10835. All from type locality.

Type Locality: Continental slope of Pernambuco ( Brazil), 08°46.5’00’’S, 34°44.5’00’’W, 690 m.

Description: Shell turriform, elongated, multispiral, somewhat slender, white porcelain ( Figs. 1, 9 ). Protoconch paucispiral 1½ whorls, smooth, glossy, bulbous, inflated, exceeding contour of first post-nuclear whorl ( Figs. 2, 8 ); transition to teleoconch with faint, sparse riblets ( Fig. 2 ). Suture linear, faintly marked ( Fig. 3 ). Teleoconch of 18 whorls on holotype, 23 whorls on paratype, flat or faintly concave. Axial ribs generally thin or obscure ( Figs. 3, 5 ). First post-nuclear whorl with 22–24 well-delineated axial ribs, extending from suture to suture. Second post-nuclear whorl with two weakly nodular spiral cords at intersection with axial ornamentation. Third whorl with subsutural cord becoming strongest, developing series of strong, raised bulges in intersection with axial ribs, projecting small shoulder. Starting at fifth whorl, all whorls develop four pronounced spiral cords, abapical thicker, strongly nodular, two peripheral cords with low nodules, one smooth suprasutural cord. Suture moderately distinct. Base flat, smooth. Aperture sub-squared. Outer lip straight, thickened, angled at corner of base. Parietal region smooth, faintly convex. Siphonal canal short, oblique, widely opened ( Figs. 4, 6 ).

Etymology: Named in accordance with the locality type, Pernambuco, state in northeastern Brazil, situated among the states of Ceará and Paraíba (to the north), Piauí (to the west), Alagoas and Bahia (to the south), with the Atlantic Ocean to the east, which presents the record of all Cerithiella known for the country thus far.

Distribution: Known only from the type locality.

Remarks: Among the Cerithiella known for the Atlantic Ocean, C. pernambucoensis is doubtlessly the most distinctive taxon due to the presence of a taller spire, with flat or faintly concave whorls, containing a greater number of spiral ornaments than what is commonly found among congeners, which generally develop three pronounced cords per whorl [ C. metula (Lovén, 1846) , with sizes of up to 12 mm, according to Fretter and Graham (1982); C. martensii ( Dall 1889: 255, pl. 20, fig. 2, length 11.25 mm); C. enodis ( Watson 1886: 541, pl. 39, fig. 3, length of syntype 4.8 mm); C. amblytera ( Watson 1886: 542–543, pl. 39, fig. 6, pl. 40, fig. 6, length 5.6 mm)], with a very thickened subsutural cord originating singular bulges that project a small carina. In rare cases, as with C. axicostulata Castellanos, Rolán & Bartolotta, 1987 , the whorls develop only axial ornaments ( Castellanos et al. 1987: 94, fig. 6, length 4.7 mm).

The general shell morphology of C. pernambucoensis is more correlated to that of C. amblytera , especially specimens from the Azores (north Atlantic) [see variability in Bouchet and Warén (1993: 598, fig. 1322)], than with specimens from Brazil due to the presence of a weak axial sculpture and the faint concavity of the whorls. The most obvious characters of the new species to distinguish it from its sympatric congeners C. amblytera include reaching a much larger adult size, developing a spire with around 6 (holotype – Fig. 1 ) to 13 (paratype – Fig. 9 ) whorls, the presence of two additional spiral cords per whorl, a very thick subsutural cord projecting vigorous, raised nodules in the intersection with the weak axial ornamentation. In C. amblytera , the abaxial cord is more pronounced and the protoconch has a smaller number of whorls. All specimens studied presented rather uniform conchological characters, with the exception of one specimen. In paratype, MNRJ 10836, the second spiral cord of the subsutural zone is absent and the axial sculpture is nearly obsolete on the whorls ( Figs. 5–6 ).

Cerithiella producta Dall, 1927 has a number of spiral ornaments that is compatible to C. pernambucoensis , but was characterized by Dall (1927: 103) as having “a fine line at the suture, a small thread a little in advance of the suture and two prominent threads near the periphery”, as well as two other less conspicuous threads at the margin of the base. This species is also similar in the faint or almost obsolete axial ribs and subsquared aperture, but, like the others, it is not as slender as C. pernambucoensis .

Figures

FIGURES 1 – 9. Cerithiella pernambucoensis n. sp. (SEM) [holotype, MNRJ]: 1. Ventral view (length: 13.3 mm), 2. Apical view, 3. Detail of ornamentation, 4. View of body whorl; [paratype, MNRJ 10836]: 5. Detail of teleococh ornamentation, 6. Body whorl, 7. Protoconch and axial ribs of the first post-nuclear whorl, 8. Apical view, 9. Ventral view (length: 16.1 mm). Scale bars: Figs. 2, 8 = 100 µm; 3, 8 = 200 µm; 4, 6 – 7 = 500 µm.