Sagenotriphora albocaput, Fernandes & Pimenta, 2020

Fernandes, Maurício Romulo & Pimenta, Alexandre Dias, 2020, Unraveling one of the ‘ Big Five’: update of the taxonomy of Triphoridae (Gastropoda, Triphoroidea) from Brazil, European Journal of Taxonomy 665 (665), pp. 1-170 : 31-32

Sagenotriphora albocaput sp. nov.

urn:lsid:zoobank.org:act:8BFB0B3F-052C-4299-B8D8-9E527FBC650D

Figs 13 , 24B , 64

Diagnosis

Embryonic shell with irregular-shaped and vesicular granules, larval shell with two spiral cords; median spiral cord emerges in the fourth whorl of the teleoconch; protoconch white, teleoconch cream to goldenbrown.

Etymology

The specific name is derived fom the Latin ‘ albus ’, meaning ‘white, clear’ and ‘ caput ’, meaning ‘summit’, and referring to its white shell apex.

Material examined

Holotype

BRAZIL – Rio Grande do Norte • 04º44′ S, 36º35′ W, BPot 1-MR43; depth 50 m; MNRJ 29393 *.

Other material

BRAZIL – Amapá • 4 specs; 03º58′43″ N, 49º33′24″ W; 2001; MNRJ 32568 * • 3 specs; 03º58′43″ N, 49º33′24″ W; 2001; MNRJ 32580 * • 1 spec.; 02º21′12″ N, 48º29′54″ W; depth 72 m; MNRJ 34458 *. – Rio Grande do Norte • 1 spec.; BPot 1-MR32; MNRJ 29394 * • 4 specs; BPot 1-MR32; MNRJ 31652 * • 15 specs; BPot 1-MR41; MNRJ 31586 * • 5 specs; BPot 1-MR42; MNRJ 29395 * • 35 specs; BPot 1-MR42; MNRJ 31587 * • 28 specs; same collection data as for holotype; MNRJ 31588 * • 8 specs; BPot 1-MR44; MNRJ 31589 * • 1 spec.; BPot 2-MR32; MNRJ 31656 * • 4 specs; BPot 2-MR41; MNRJ 31638 * • 14 specs; BPot 2-MR42; MNRJ 31636 * • 19 specs; BPot 2-MR44; MNRJ 31639 * • 7 specs; BPot 2-MR45; MNRJ 31646 *. – Fernando de Noronha Archipelago • 2 specs; Jan. 1979; MORG 20634 *.

Description

Shell sinistral, small, elongated, cyrtoconoid, slightly convex profile, up to 3.5 mm long, 1.1 mm wide, length/width ratio 2.7 to 3.1. Protoconch multispiral, conical, 4–4.25 whorls, 0.40–0.45 mm long, 0.35–0.39 mm wide; embryonic shell dome-shaped, covered by irregular, often rounded granules, and vesicular, axially-disposed granules appearing predominantly in the final and abapical portion of embryonic shell, resulting in axial ribs of the larval shell; larval shell with two spiral cords, situated at 29%–37% and 60%–65% of last whorl height; ~34 nearly rectilinear axial ribs; transition to the teleoconch defined by an often inconspicuous scar. Teleoconch with up to eight whorls; two spiral cords (adapical and abapical) at the beginning, the abapical one continuous to that of the protoconch; median spiral cord emerges in the fourth whorl (rarely at the end of the third or at the very beginning of the fifth whorl), reaching same size of abapical cord (adapical one slightly more prominent in late whorls) after 2.0 to 2.5 whorls; on the body whorl, the spiral cords are 1.1–1.8 × as wide as the distance between them; 19–21 nearly orthocline axial ribs; rounded nodules of medium size; distinct, well-developed suture, with a small sutural cord; slightly wavy to nearly smooth subperipheral cord, two smooth basal cords; three distinct supranumerical cords, one between median and abapical spiral cords, another between abapical and subperipheral cords, and a small one between subperipheral and adapical basal cords; ovate aperture, 0.51–0.60 mm long, 0.42–0.53 mm wide, length/width ratio 1.1 to 1.4; anterior canal moderately short, curved backwards/downwards, partly or almost closed, 0.16–0.23 mm long, 0.12–0.16 mm wide, length/width ratio 1.0–1.7; deep posterior canal, 0.12 mm long, not detached from aperture. White protoconch, cream to golden-brown teleoconch.

Remarks

The generic placement of this species was based on the sculpture of the embryonic shell ( Fig. 13 L–M), the presence of two continuous spiral cords in the larval shell ( Fig. 13 I–K), the smooth subperipheral and basal cords ( Fig. 13H ), and the presence of supranumerical cords ( Fig. 13G ). Although not all of them are shared with the type species Sagenotriphora ampulla (Hedley, 1903) , these features are quite similar to those of Sagenotriphora osclausum ( Rolán & Fernández-Garcés, 1995) and Sagenotriphora candidula Rolán & Lee, 2008 ( Fig. 14 ), but S. albocaput sp. nov. is unique by having a white protoconch and a cream to golden-brown teleoconch ( Fig. 13 A–D). This coloration is similar to that of Isotriphora tricingulata , but the latter species has a paucispiral protoconch ( Fig. 3I ).

Geographical records

Brazil: Amapá, Rio Grande do Norte and Fernando de Noronha.

Bathymetric distribution

Depth: 20– 72 m.

Figures

Fig. 13. Sagenotriphora albocaput sp. nov. A. MNRJ 29393*, holotype, 2.84 mm. B. MNRJ 29394*, 3.00 mm. C. MORG 20634*, 2.49 mm. D. MNRJ 32580*, 2.82 mm. E–F, H. Same shell as B. G, J, M–N. MNRJ 29395*. I, L. MNRJ 31652*. K. Same shell as D. Scale bars: A–E = 1 mm; F–H = 500 µm; I–K, N = 100 µm; L–M = 50 µm.

Fig. 24. Triphoridae from Brazil (3). A. Nototriphora decorata (C.B. Adams, 1850). B. Sagenotriphora albocaput sp. nov. C. Sagenotriphora osclausum (Rolán & Fernández-Garcés, 1995). D. Sagenotriphora sp. 1. E. Sagenotriphora sp. 2. F. Similiphora intermedia (C.B. Adams, 1850). G. Similiphora lucida sp. nov. H. Similiphora sp. 1. I. Strobiligera campista Fernandes & Pimenta, 2019. J. Strobiligera delicata Fernandes & Pimenta, 2014. K. Strobiligera dinea (Dall, 1927). L. Strobiligera gaesona (Dall, 1927). M. Strobiligera inaudita (Rolán & Lee, 2008). N. Strobiligera santista Fernandes & Pimenta, 2019. O. Strobiligera unicornium (Simone, 2006). P. Strobiligera sp. 1. Q. Strobiligera sp. 2. R. Triphora atlantica Smith, 1890. S. Triphora charybdis Fernandes & Pimenta, 2015. T. Triphora ellyae De Jong & Coomans, 1988. U. Triphora elvirae De Jong & Coomans, 1988. V. Triphora portoricensis Rolán & Redfern, 2008. W. Triphora scylla Fernandes & Pimenta, 2015. Scale bars: 1 mm.

Fig. 64. Distribution map of Sagenotriphora albocaput sp. nov. (red circle = type locality; black circles = additional localities) and Sagenotriphora sp. 2 (gray circle).

Fig. 14. Types of Sagenotriphora candidula Rolán & Lee, 2008. A. FLMNH 419189, holotype, 5.00 mm. B–E. FLMNH 249739, paratypes, 4.46 mm, 4.44 mm, 4.77 mm and 4.18 mm, respectively. F. BMSM 15202, paratype, 3.80 mm. G. FLMNH 178388, paratype, 4.38 mm. H. FLMNH 154860, paratype, 4.51 mm. I. FLMNH 127829, paratype, 4.44 mm. J. USNM 1112659, paratype, 4.66 mm. Scale bars: 1 mm.

Fig. 3. Isotriphora tricingulata Rolán & Fernández-Garcés, 2015. A, C. MNRJ 32558*, 2.75 mm and 3.04 mm, respectively. B. MNRJ 17929*, 4.62 mm. D. MNRJ 32574*, 3.29 mm. E–I, K. Same shell as A. J. Same shell as D. Scale bars: A–E = 1 mm; F–H = 500 µm; I–K = 100 µm.