Nanaphora verbernei ( Moolenbeek & Faber, 1989 ) Moolenbeek & Faber, 1989

Fernandes, Maurício R. & Pimenta, Alexandre D., 2015, Five new species and two records of Triphorinae (Caenogastropoda, Triphoridae) from Brazil, Zootaxa 4012 (3), pp. 493-513 : 500-503

Nanaphora verbernei ( Moolenbeek & Faber, 1989) comb. nov.

( Figure 4 )

Triphora verbernei Moolenbeek & Faber, 1989: 77 , figures 6–8.

Cheirodonta verbernei: Rolán & Fernández-Garcés (1994 : 20, figures 17–18, 22, 30 CV; 2007: 18, plate 1, figures 17–18, not the lapsus calami of Cosmotriphora verbernei at page 20).

Type material. Holotype: ZMA 3.89.0 13. Paratypes: ZMA 3.89.0 14 [19].

Type locality. Curaçao.

Material examined. Brazil: Alagoas state: MORG 33734, Jaraguá, Maceió, P.S. Cardoso coll. [4]. Bahia state: MZSP 64881, Salvador [1]; MORG 52591, Abrolhos, Eq. MORG coll., i/1985 [2]. Espírito Santo state: IBUFRJ 12884, REVIZEE C1-VV24 [1]; MNRJ 33982, 20º42’00”S, 40º24’28”W, Ilha Escalvada, Guarapari, 10–15 m, M.R. Fernandes & L.S. Souza coll., 12/x/2014 [1]; MNRJ 34029, 20º42’00”S, 40º24’28”W, Ilha Escalvada, Guarapari, W. Vieira coll., i/2013 [1]. Rio de Janeiro state: MNRJ 18756, 22º42’S, 40º40’W, 2006 [4]; MNRJ 33139, 22º42’S, 40º40’W [1]; IBUFRJ 19686, Praia da Figueira, Angra dos Reis [3]; UERJ 5792, 23º01’55”S, 44º22’44”W, 6 m, Ilha da Gipóia, 28/x/2003 [4]; UERJ 5181, 23º06’07”S, 44º11’27”W, 6 m, Ponta da Enseada, Ilha Grande, 01/xii/2003 [2]; UERJ 3792, 23º11’36”S, 44º38’37”W, 4.5 m, Praia Vermelha, Paraty, 18/xi/2003 [4]. São Paulo state: MZSP 85022, Ilha da Queimada Pequena, Itanhaém, 0-12 m [2].

Description. Shell sinistral, elongated, almost biconical/ovoid, profile slightly or overtly curvilinear, reaching 3.66 mm in length, 1.57 mm in width. Protoconch golden-brown; teleoconch with reddish-brown background, whitened nodules; first two whorls of teleoconch lighter in color than remaining whorls; adapical spiral cord usually somewhat darker than other cords, but it may well be somewhat lighter in other shells, especially on body whorl, or not having differences in coloration among spiral cords. Protoconch conical, 0.45–0.55 mm in length, 0.34–0.39 mm in width, with 4.5 to 5 convex whorls; embryonic shell dome-shaped, with a reticulated pattern of spiral and axial threadlets; larval shell with two spiral cords, adapical one initially weaker and returning to vanish in the last whorl, disappearing just before transition to teleoconch; about 32 almost rectilinear to slightly sigmoid axial ribs. Teleoconch with up to eight whorls; two spiral cords (adapical and abapical) on the first whorl, abapical one continuous with that of protoconch; median spiral cord emerges between end of fifth and seventh whorl, reaching same size as other cords after 0.75 to one whorl; 20 to 23 axial ribs, with undulating arrangement varying from slightly prosocline (nearly orthocline) to slightly opisthocline; large rounded nodules; suture barely distinct, with a small sutural cord; nodulose subperipheral and adapical basal cords, wavy abapical basal cord; two small supranumerical cords may develop near the peristome, one between median and abapical spiral cords, the other between abapical and subperipheral cords; aperture ovate; anterior canal curved backward/downward, being small and open, but crossed on its base by projection of outer lip; posterior canal as a deep sinus, almost detached from aperture in some cases.

Remarks. The original description of N. verbernei indicates that the adapical spiral cord of the larval shell emerges only on its second whorl. Amplified images of the protoconch ( Fig. 4 H; Rolán & Fernández-Garcés 1994: fig. 22) show that the adapical cord, although initially weaker than the abapical one, also emerges on the first larval shell whorl.

Maximum length of shells of N. verbernei from Brazil were very similar to Caribbean ones, reaching 3.66 mm and eight teleoconch whorls in the present study, but 3.50 mm ( Rolán & Fernández-Garcés 2007) or 3.20 mm ( Moolenbeek & Faber 1989) and seven teleoconch whorls in the Caribbean. Such dimensions make N. verbernei one of the smallest species of Triphoridae in the western Atlantic.

The type material of Cerithium exiguum C.B. Adams, 1850 , a species originally described from Jamaica, is lost ( Clench & Turner 1950). Following its original description, many similarities are shared with N. verbernei , like the ovoid shape of the shell, the “wax” coloration, presence of large nodules, a barely distinct suture, the short anterior canal and small shell dimensions (type material of C. exiguum reaches 2.29 mm in length, 0.89 mm in width). De Jong & Coomans (1988) recorded Triphora exigua (C.B. Adams) from Aruba, Bonaire and Curaçao, emphasizing the indistinct suture and the completely or partly white adapical spiral cord on the body whorl (which can also occur with N. verbernei ), in addition to a maximum size of 3.7 mm in length and 1.3 mm in shell width; Díaz Merlano & Puyana Hegedus (1994) recorded T. exigua from Colombia. However, the brief original description of T. exigua also renders it similar to Sagenotriphora osclausum ( Rolán & Fernández-Garcés, 1995) , as mentioned by Lee (2009). To avoid taxonomic problems, Rolán & Fernández-Garcés (2007) considered T. exigua a nomen dubium. Material studied by De Jong & Coomans (1988) and Díaz Merlano & Puyana Hegedus (1994) needs to be taxonomically reevaluated, as they did not illustrate shells identified as T. exigua .

Moolenbeek & Faber (1989) described the embryonic shell of N. verbernei as smooth, but the protoconch of the holotype is polished by erosion ( Rolán & Fernández-Garcés 1994). Rolán & Fernández-Garcés (1994) described this embryonic shell as being covered by hemispheric tubercles, but the illustrated protoconch has a fracture zone that hampers a correct evaluation. In fact, the embryonic shell of N. verbernei is reticulated ( Fig. 4 I), contrary to the description of the genus Cheirodonta Marshall, 1983 , whose type species C. pallescens has an embryonic shell mainly covered by granules ( Marshall 1983, Bouchet 1985).

Besides differences in embryonic shell sculpture, the generic allocation of N. verbernei in Cheirodonta by Rolán & Fernández-Garcés (1994) raises other conflicts with C. pallescens , like differences in radular (especially in relation to the central tooth) and shell morphology ( N. verbernei with ovoid shell shape and nodulose subperipheral and adapical basal cords). In addition, all Caribbean species designated by Rolán & Fernández-Garcés (1994) and Rolán & Luque (1999) as Cheirodonta are smaller than 4.0 mm in shell length, instead of 8.0 mm in C. pallescens ( Bouchet 1985) . As previously mentioned, the Pacific species Cheirodonta labiata was also tentatively allocated in this genus ( Marshall 1983); in fact, it is more similar to the Caribbean species Cheirodonta apexcrassum Rolán & Fernández-Garcés, 1994 and Cheirodonta miskitorum Rolán & Luque, 1999 .

The paucispiral protoconch of the type species of Nanaphora , Nanaphora torquesa Laseron, 1958 , does not provide characters to suggest its affinities ( Marshall 1983), and this is worsened by its unknown radula. However, conchological characters cited for the genus by Laseron (1958) and Marshall (1983), like the ovoid shape, small length and barely distinct suture, point to an allocation of N. verbernei in this genus. The ovoid shape of most shells of N. verbernei ( Fig. 4 A, D) is an intermediate level between that of the type species (less ovoid) and that of Nanaphora albogemmata ( Laseron, 1958) (more ovoid).

Nanaphora is possibly a polyphyletic genus, comprising species with different embryonic shell sculpture and larval shell with one or two spiral cords ( Marshall 1983). The affinity among the genera Nanaphora, Opimaphor a and Cheirodonta makes necessary a taxonomic revision of them to achieve a precise delimitation of each genus. Despite this, the following Caribbean species are herein transferred to Nanaphora : N. apexcrassum comb. nov., N. miskitorum comb. nov. and Nanaphora decollata ( Rolán & Fernández-Garcés, 1994) comb. nov.

Geographic distribution. Cuba ( Rolán & Fernández-Garcés 1994); Cayman Islands ( Rosenberg 2009); Puerto Rico ( Moolenbeek & Faber 1989); Grenada ( Rosenberg 2009); Bonaire and Curaçao (type locality); Brazil: Alagoas, Bahia to São Paulo (present study).

Bathymetric distribution. Intertidal to 90 m ( Moolenbeek & Faber 1989).

Figures

FIGURE 4. Nanaphora verbernei comb. nov. A – C. MNRJ 18756. A. Shell from Brazil, 3.29 mm long. B. Idem, 3.40 mm long. C. Idem, 3.25 mm long. D. Idem, MZSP 85022, 3.20 mm long. E, G, same shell as D. F, H – J, same shell as A. Scale bars: A – D, F, 1 mm; E, G, 500 µm; H, J, 100 µm; I, 50 µm.