Cerithiopsis favus, Pimenta & Faria & Figueira & Fernandes, 2024

Pimenta, Alexandre Dias, Faria, Raquel Garofalo De Souza, Figueira, Raquel Medeiros Andrade & Fernandes, Maurício Romulo, 2024, Unraveling another of the ‘ Big Fiveʹ: new species and records of Cerithiopsidae from Brazil (Caenogastropoda: Triphoroidea), Zootaxa 5494 (1), pp. 1-71 : 51-53

Cerithiopsis favus sp. nov.

urn:lsid:zoobank.org:act:7B86E6B9-8539-4C99-B480-C3828219E9A4

( Fig. 27 )

Type material. Holotype: IBUFRJ 19642 . Paratypes: Brazil: -- Rio de Janeiro state: HAB 11 sta. B4 : MNRJ 18732 [*1p]; HAB 16 sta. B5 : MNRJ 16577 [1*p] , MNRJ 18735 [1*p]; 23°05ʹS, 40°58ʹW, 100 m, 16–17/ix/2004 : MNRJ 30858 [*1p]; 22°42ʹS, 40°40ʹW, xii/2001 : MNRJ 31377 [*4p] .

Type locality. Brazil, off Rio de Janeiro state, Campos Basin , 106–110 m, Oceanographic Ship Almirante Câmara coll., 20–27/1/1998 :

Additional material. Brazil: -- Espírito Santo state: HAB 17 sta. I3 : MNRJ 16578 [2*]; -- Rio de Janeiro state: HAB 13 sta. H4 : MNRJ 16225 [1*]; HAB 11 sta. B5 : MNRJ 16223 [1*]; 22°42ʹS, 40°40ʹW, xi/2007 : MNRJ 31374 [2*] , MNRJ 31375 [1*]; 22°42ʹS, 40°40ʹW, 110–120 m, 19/ix/2003 : MNRJ 31378 [4*]; 23°04ʹS, 40°59ʹW, 17/xii/2004 : MNRJ 33021 [4*]; 23°05ʹS, 40°58ʹW, 100 m, 16–17/ix/2004 : MNRJ 31379 [1*] .

Etymology. From the Latin word favus = honeycomb. This species is named after the pitted protoconch sculpture resembling the cells of a honeycomb.

Diagnosis. Protoconch conical with pitted, honey-comb like sculpture on embryonic whorl, subsequent whorls with two spiral cords. Teleoconch with the two adapical spiral cords close to each other in the initial whorls, the adapical one less prominent, becoming separated in body whorls.

Description. Shell elongated, slender, high-spired, up to 4.1 mm long, 0.7 mm wide, ratio length/width 4.1–4.4. Protoconch cylindrical, white to orange-brownish, 579–658 µm long, 335–415 µm wide, with 3.0–3.5 whorls; embryonic shell globose, covered by pits, resulting in a rugose, honeycomb-like surface; larval shell with two smooth spiral cords, situated at 30–46% (abapical) and 61–76% (adapical) of whorl length, and no axial sculpture (only growth lines). Teleoconch with up to 10 whorls, rectilinear profile; color light brown, orange-brownish or beige, some shells with the initial whorls whitish; three spiral cords, the adapical cord close to the median one and initially rather weak, gradually strengthening but never reaching the same strength as other cords; ~18 orthocline axial ribs on the body whorl; rounded, medium-sized nodules (occupying ~45% of body whorl length) at intersections of spiral cords and axial ribs; shallow suture, with a thin sutural cord immediately above the adapical cord; subperipheral cord slightly nodulose to nearly smooth; base concave, without basal spiral cord; aperture small, subcircular, 0.49–0.56 mm long, ~ 0.40 mm wide, ratio length/width 1.2–1.4; short, open anterior canal, discrete posterior sinus; inner lip slightly reflected over the parietal wall; outer lip crenulated due to projections of spiral sculpture of body whorl.

Remarks. Cerithiopsis favus sp. nov. shares some similarities with the Cerithiopsidae species currently allocated under Belonimorphis Jay & Drivas, 2002 , whose type species, Belonimorphis belonimorphis Jay & Drivas, 2002 , is from the Reunion Island.

The shell shape of C. favus is turriform( Fig.27A–E ), without the discrepant bottle-shaped shell (with a constricted apex) of most Belonimorphis species, although the type species has an intermediate form. In all Belonimorphis species (except the type species), on initial teleoconch whorls the adapical of the three spiral cords soon fuses with the median spiral cord, to further split again in late whorls; in C. favus ( Fig. 27A – F ) and B. belonimorphis , the adapical spiral cord is smaller in size throughout the teleoconch, but it never fuses with the median one. In all Belonimorphis species (including the type species), there is at least one basal cord, absent in C. favus ( Fig. 27G ).

One evident difference between C. favus and B. belonimorphis is the sculpture of the protoconch.The protoconch of B. belonimorphis is similar to that of the triphorid genus Inella (e.g., Fernandes & Pimenta 2019b), with all whorls similar similar to each other, having two spiral cords. In contrast, the protoconch of C. favus ( Fig. 27H – J ) has a rugose and slightly inflated embryonic shell and a larval shell with two spiral cords. This kind of protoconch sculpture is similar to that of some of the remaining species currently allocated under Belonimorphis .

Owing to all these differences in the shell and the several possible examples of convergence or perhaps parallelism in paucispiral protoconchs of Triphoroidea ( Fernandes & Pimenta 2019b, 2020), we prefer to keep this species in the “catch-all” taxon Cerithiopsis than to widen the concept of Belonimorphis even more.

Geographic and bathymetric distribution. Only known from Rio de Janeiro state, in the Tropical Southwestern Atlantic Province . From 88 m to 141 m.

Genus Belonimorphis Jay & Drivas, 2002

Type species. Belonimorphis belonimorphis Jay & Drivas, 2002 , by original designation.

Figures

FIGURE 27. Cerithiopsis favus sp. nov. A: holotype, from Rio de Janeiro state (MNRJ 19642); B–I: paratypes from Rio de Janeiro state (B: MNRJ 30858; C: MNRJ 18732; D, F, H: MNRJ 16577; E, I: MNRJ 31377; G, J: MNRJ 18735); F: detail of teleoconch whorls of shell in D; G: body whorl; H–I: protoconchs of shell in D and E, respectively; J: detail of embryonic whorl. Lengths of whole shells: A: 4.0 mm; B: 4.8 mm; C: 4.8 mm; D: 4.8 mm; E: 3.6 mm. Scale bars: A–E: 1 mm; F–G: 200 µm; H–J: 100 µm.