Aforia goniodes Watson 1881

Aforia goniodes (Watson, 1881)

Figures 1 A–P; Figures 2 A–H; Figures 3 A–C

Pleurotoma clara Martens, 1880: 35, pl. 8, fig. 1 a–d (letters missing on the plate) non Reeve, 1845; Strebel, 1905: 578. Pleurotoma (Surcula) goniodes Watson, 1881: 394; 1886: 291, pl. 20, fig. 4.

Surcula clara von Martens. Tryon, 1884: 239, pl. 6, figs. 77, 77a; Carcelles, 1944: 8, pl. 1, fig. 4; 1950, pl. 3 fig. 47. Aforia goniodes (Watson). Powell, 1951: 168; Carcelles and Williamson, 1951: 307; Powell, 1960: 158; 1966: 43, pl. 5, figs.

12, 13; Castellanos, 1970: 131, pl. 10, fig. 8; Castellanos et al., 1987: 63, pl. 2, fig. 15; Castellanos and Landoni, 1993: 5,

pl. 1, fig. 6, pl. 3, fig. 28 (not 27 as written in the text); Forcelli, 2000: 108, fig. 318; Engl, 2012: 179, pl. 73, fig. 1. Aforia gonioides (in error pro goniodes) (Watson, 1881). Dell, 1990: 234, figs. 402, 403.

Description. Shell large, up to 39 mm height, fusiform, elongated, translucent (when young) or chalky whitish, grey; protoconch paucispiral, globose, about 2 whorls (~ 0.9 mm width x 1.32 mm height), first with irregular spiral wrinkles forming a net that soon disappears in teleoconch; transition to teleoconch gradual; teleoconch whorls with a conspicuous protruding keel in the periphery; axial ornamentation of irregularly spaced growth lines; spiral ornamentation of weak threads, 3 in the first two whorls increasing to 7 on third, 12 on the fourth and fifth, to 57 in the last whorl below keel; above keel, 4–5 on first whorl, 6 on second and third to 17 on the fourth and fifth; some specimens with more developed cords in the last whorl; subsutural ramp slightly concave in the first whorls, flat in the middle to weakly convex in the last; aperture elongated tapering towards the siphonal canal; outer lip with a deep anal sinus above keel; teleoconch first whorls covered by axially organized granules following shape of the anal sinus, disorganized below the keel; anal sinus, already present in almost hatched embryos, with its deepest part situated always at mid-distance between the keel and the suture.

Operculum sub oval (adults), elongated (juveniles), with subterminal nucleus, close to the internal margin, growth lines well defined, regularly spaced, inner surface with a thick rim and attachment area distinct, semitranslucent, brownish.

Radula of type 3 “ Turridae ” according to Kantor & Taylor (2000), short, rachidian very thin, markedly curved, unicuspid, often without any trace of a central cusp, with curved base, marginal teeth duplex with a thin, wide, flat major element; accessory limb elongated, thin, separated from major element, the latter with a weak but perceptible constriction in the base of the tip of the “arrow”; accessory limb base attached to radular membrane and major element.

Penis large, flat with terminal papilla surrounded by a collar. Eyes large on the base of tentacles, always visible. Table 2 summarizes shell measurements.

Type material. [goniodes] Holotype, NHMUK 1887.2.9.970 (Plate 1, figures A–C); [clara] holotype, ZMB 27329 (Plate 1, figures G–H).

Type locality. [goniodes] South-east of Rio de La Plata, 37°17'S, 52°52'W, Argentina, in 600 fathoms (~ 1,097 m), St. 320 of HMS “CHALLENGER” expedition; [clara] Patagonia, 60 fathoms (~ 110 m), S.M.S. “GAZELLE” expedition.

Material examined. MACN-In 25525, 35°37’S, 55°55’W collected in 210 m (115 fathoms), 1 specimen; specimens from stations of “ Talud Continental ” expedition of R/V “PUERTO DESEADO”: MACN-In 40488, St. 6, 37º58.337´S, 55º8.915´W, in 530 m depth, 1 specimen; MACN-In 40482, St. 10, 37º59.706´S, 54º41.854´W, 852 m, 12 shells and 3 specimens; MACN-In 40489, St. 12, 37º57.907´S, 54º31.921´W, in 1144 m depth, 1 shell and 1 specimen; MACN-In 40486, St. 14, 38º0.984´S, 54º30.326´W, in 1006 m depth, 4 shells; MACN-In 40484, St. 38, 37º59.308´S, 54º25.207´W, in 1099 m depth, 1 shell; MACN-In 40490, St. 41, 38º0.1631´S, 54º30.275´W, in 997 m depth, 3 shells and 1 specimen; MACN-In 40487, St. 43, 37º53.837´S, 54º30.458´W, in 998 m depth, 2 shells and 4 specimens; MACN-In 40491, St. 44, 37º53.557´S, 54º42.941´W, in 780 m depth, 2 shells; MACN-In 40485, St. 51, 38º1.447´S, 53º51.011´W, in 2212 m depth, 5 shells and 3 specimens; MACN-In 40483, St. 59, 37º49.688´S, 54º5.236´W, in 1398 m depth, 3 shells and 7 specimens; MACN-In 40492 St. 64, 37º49.661´S, 54º7.943´W, in 1395 m depth, 1 specimen.

Distribution. Known from the Magellanic region (Powell, 1951) to 37°S in 530 to 2,212 m depth.

Remarks. The material housed at the NHMUK is actually a single and badly worn specimen, probably inhabited by a sipunculid. Nevertheless new material collected from a station very close to the original sampling site confirmed the geographic distribution and clarify the shell morphology of the species. A. goniodes was described a year later with no mention of Pleurotoma clara. Strebel (1905) was the first to refer to Martens’ species reporting about its dubious validity. The type material of P. c l ar a Martens is housed at Museum für Naturkunde, Berlin and illustrated here for the first time. P. c l ar a is a junior homonym of Reeve (1845), so the name is not available. We agree with Powell (1951) that considers both names as synonyms.

The SEM pictures of A. goniodes showed the presence of granules all along the shell, a diagnostic character absent in the other species here studied (see Plate 2, figures F–H). As this character is only visible thru SEM and nothing is known of other species, it is here consider as specific.

According to the subgeneric arrangement proposed by Sysoev & Kantor (1987) that considers the ratio of shell height to length of marginal teeth, this species belongs in Aforia s.s.