Aeneator martae, Araya, Juan Francisco, 2013

Araya, Juan Francisco, 2013, A new species of Aeneator Finlay, 1926 (Mollusca, Gastropoda, Buccinidae) from northern Chile, with comments on the genus and a key to the Chilean species, ZooKeys 257, pp. 89-101 : 91-95

Aeneator martae sp. n. Figs 1-14, 18, Tables 1, 2, 3

Type material.

Holotype (MZUC 37890), 47.9 mm. Chile, off Caldera (27°04'S, 70°50'W), 550-600 m depth, live collected on shrimp trawl nets, January 2001, S. Castillo leg. Paratype 1 (MZUC 37891), length 44.0 mm. Paratype 2 (MZUC 37892), 41.7 mm, Paratype 3 (MG 200105), length 40.2 mm. All the paratypes with same locality as the holotype.

Distribution.

Known only from the type locality; Chile, Region de Atacama, Caldera (27°04'S, 70°50'W), 550-600 m depth.

Diagnosis.

A small species of Aeneator , height up to 47.9 mm, shell stout, inside of aperture pale orange, exterior sculptured by well-defined axial ribs, spiral cords, and a conspicuous stepped shoulder.

Description.

Shell small for genus (height up to 47.9 mm, Table 1), thick, solid, fusiform, chalky white to pale brownish, inside of aperture pale orange. Shape broad, angulate, length of aperture and canal more than half length of shell, width/height ratio 0.53 to 0.56, whorls convex apart from slightly concave sutural ramp, suture shallow but impressed. Spire angle 63° to 68°. Protoconch and upper teleoconch whorls missing, remaining whorls about 4.5, last 3 with sculpture intact with 7-9 primary spiral cords, interspaces each occupied by one narrow, well defined secondary cord. Last whorl with 16-18 spiral cords, more prominent at periphery of shell than elsewhere, forming a distinct keel. Spire whorls with 24-28 pronounced axial ribs, interspaces deep, each almost equal to a rib in width. Last whorl with 14-15 such ribs. Ribs more pronounced towards the anterior end of shell. Aperture ovate. Parietal and columellar area well-defined, glazed; outer lip thin, slightly crenulated, without lirae or teeth. Siphonal canal short, open, directed slightly to left. Operculum large, thin, dark brown, elongate, nucleus terminal, tip sharp.

Etymology.

Named in honour of Mrs Marta Araya,Caldera, Chile, who presented the specimens to the author.

Remarks.

In Chile the genus Aeneator encompasses five extant species: Aeneator castillai , found from Coquimbo (29°55'S) to Punta Peñablanca (33°22'S) in 200-450 m ( McLean and Andrade 1982), Aeneator fontainei , the most common species, with records from Bahía Independencia (14°S) in the south of Peru ( McLean and Andrade 1982) to Estero Elefantes, 46°05'S ( Osorio et al. 2006) and with a bathymetric range of 10 m near Mejillones ( Guzmán et al. 1998, Laudien et al. 2007) to 421 m for a specimen collected off Coquimbo (Figs 27-30), Aeneator (Ellicea) loisae , distributed from Caldera (27°04'S), for material examined in this work (Figs 27-30), to Canal Moraleda (45°22'S), in the fjords area ( Osorio et al. 2006) with a bathymetric range of 200 m (McLean & Andrade 1982) to 465 m, Aeneator portentosus reported only form the original locality off Iquique (21°19'S) in 605 m and off Coquimbo at 800 m and Aeneator prognaviter , distributed off Antofagasta (22°51'S) in 318 m ( Fraussen and Sellanes 2008) and in 748 m off Iquique for material examined in this work (Fig. 37). Data on the localities of Chilean species of Aeneator is provided in Table 3.

In size, the shell of Aeneator martae sp. n. is similar to Aeneator prognaviter (Figs 20, 37, 38) and Aeneator portentosus (Figs 35, 36). However, the former of these two can be clearly differentiated from the new species by its wider and shorter siphonal canal, less numerous and more curved axial ribs and a thinner, snow white shell ( Fraussen and Sellanes 2008). From Aeneator portentosus the new species differs by having a much wider, thicker shell with a shorter spire, a more elongate aperture, dominant axial sculpture and less rounded whorls. Moreover Aeneator portentosus exhibit a very distinctively sculptured peri ostracum (Fig. 19), with low axial ridges, very different from all the other Chilean Aeneator species. A periostracum is absent in the examined specimens of Aeneator martae sp. n.

Aeneator castillai (Figs 33, 34), and Aeneator fontainei (Figs 21-26) differ markedly from the new species by their much larger shells, reaching up to 85.8 mm, more fusiform shells, with a much less stepped or indistinct shoulder, lower and fewer axial ribs, brown primary spiral cords (Figs 15, 16) and lip lirated within. The spiral sculpture is quite different; Aeneator fontainei has 13 to 16 dark brown major cords, with interspaces filled with five secondary cords separated by fine grooves or by secondary and tertiary cords. Aeneator castillai has brown primary cords with 3 to 5 fine secondary cords fill ing the interspaces and exhibits a longer, twisted, siphonal canal. In contrast Aeneator martae sp. n. lacks any brown coloration, shows a sculpture of alternated single major and minor spiral cords defined mostly in the posterior part of the whorls, and has a conspicuous stepped shoulder, forming a keel at the periphery.

Aeneator loisae (Figs 27-32) differs from the new species in having a larger, up to 104 mm, white to snow white shell (different from the white to light brown shell of Aeneator martae sp. n.), more inflated last whorl, with a much longer siphonal canal, a higher number of primary and secondary spiral cords, more prominent spiral sculpture, and fewer, more tenuous, axial ribs.

The new species is tentatively assigned, given the generic uncertainties within the Chilean species, to the genus Aeneator Finlay 1926, typified by the species Aeneator marshalli marshalli (Murdoch, 1924) recorded from Castlecliff (as fossils) and, as a recent species (= Aeneator marshalli separabilis Dell, 1956), from Wanganui and Ohope beach, Whakatane, New Zealand. Similar to the type species, Aeneator martae sp. n. has a fusiform shell with moderately tall spire, shallow sinus in outer lip and a spiral sculpture of cords crossed by axial costae ( Beu and Maxwell 1990). The new species differs from Aeneator marshalli in its smaller shell, shorter anterior canal, the absence of nodules along the columellar lip, less inflated whorls and by the presence of a distinct keel at the periphery. From the genus Austrofusus Kobelt, 1879, with the type species Austrofusus glans ( Röding, 1798), the new species differs in the smaller size, its thicker shell, more prominent sculpture, the more prominent ridges over the periphery, and the pale orange colour of the aperture, which is white in Aeneator glans (Beu & Marshall 2010). Comparative characters in the Chilean species of Aeneator are compared in table 2.

In a recent revision of the fossil fauna of Mejillones, north of Chile ( Nielsen 2012), the species Aeneator loisae was synonymized with the fossil species Fusus steinmanni Möricke, 1896 into Austrofusus . However, this was based partly on the incorrect conclusion by Beu and Marshall (2010) that Aeneator fontainei is the type species of Austrofusus ; this was later corrected by Beu and Marshall (2011). On morphological grounds, the author concurs with McLean and Andrade (1982) and considers that Aeneator (Ellicea) loisae does belong to the genus Aeneator and the sub-genus Ellicea Finlay in Marwick, 1928. However the generic placement of the species Aeneator fontainei , Aeneator castillai , and possibly the new species described here, should be further investigated or even be ascribed to a new genus.

Further study of radular characters, comparative anatomy and DNA will improve the taxonomic placement of the Chilean species. Fossil studies would also give a general insight into the development of the genus and their relationships with the South Pacific related fauna, especially those from New Zealand and adjacent waters.

Comparative material examined:

Aeneator castillai , Chile, Region of Coquimbo, Coquimbo, 2 specimens RC Coll. Aeneator fontainei , Chile, Region of Atacama, Caldera, 3 specimens MG 200011-200013, 5 specimens RC Coll. Aeneator loisae , Chile, Region of Atacama, Chile, 4 specimens MG 200003-200006, 1 specimen RC Coll, Aeneator prognaviter , 2 specimens MG 200124-200125, Aeneator portentosus , 1 specimen (examined from images), KF-0338.