Acamptodaphne eridmata, Morassi & Bonfitto, 2010

Morassi, M. & Bonfitto, A., 2010, New raphitomine gastropods (Gastropoda: Conidae: Raphitominae) from the South-West Pacific, Zootaxa 2526, pp. 54-68 : 59

Acamptodaphne eridmata new species

Figures 1. P–V

Type material: Holotype NMNS 6329-001 and paratype MNHN 22303 .

Type locality: Taiwan, Bashin Channel , 22°.01.8" N 120° .26.6'E

Material examined: Taiwan: Bashin Channel, 22°.01.8" N 120°.26.6'E, 246 m [N/ O Fisher Researcher 1, Taiwan 2000, stn. CP 35] (holotype) . Solomon Islands: 8°21.4" N 160°41.8 "E, 194–286 m [N/ O Alis, SALOMON 1, stn. DW 1768] (paratype)

Description: Shell biconic (b/l 0.47–0.51; a/l 0.51–0.55). Teleoconch consisting of 5 whorls, which are shouldered at one-fourth of whorl height on the first two whorls, and at one-third of whorl height on subsequent ones. Last whorl broadly excavated with a relatively long neck. Whorls separated by deep, narrowly channelled suture, bordered by a wide, prominent subsutural fold. Sutural ramp wide, shallowly concave. Axial sculpture consisting of short, weakly prominent, opisthocline ribs, with interspaces equal or wider than them, extending on spire whorls from lower suture to shoulder angle, where they are abruptly truncated and form rounded tubercles at periphery. There are 25–29 ribs on penultimate whorl; on last whorl ribs rather weak, occupying only periphery and becoming obsolete on latter part of whorl. Spiral sculpture commencing as a cord, forming peripheral angulation, joined during growth by low, flattened, weaker cords on sides; three closely spaced cords occur at peripheral angulation on two later whorls. Below these peripheral cords there are 2 cords on penultimate whorl increasing to 4–5 on last whorl. Sutural ramp sculptured with 2– 3 spiral cords and 2 threads on two later whorls. Subsutural fold sculptured with 5–6 closely spaced spiral threads. Base with 22–23 spiral elements including cords and occasional interstitial threads. Whorls covered by dense, rough collabral growth lines particularly evident on sutural ramp where are sinuous in conformity with the anal sinus in outer lip; the growth lines form small, axially elongate tubercles on subsutural fold and small nodules at points of intersections with spiral cords. Under SEM, entire shell surface is seen to be covered by rows of microscopic granules. Aperture lanceolate. Columella almost straight above, curved to left below. Labial callus thin, sculptured by microscopic irregular linear corrugations of the surface with sharp edges. Siphonal canal short, oblique, wide. Outer lip thin, with a moderately deep, broadly reversed L-shaped anal sinus; its apex below middle of sutural ramp. Protoconch conical of 2.75 whorls; protoconch I covered with minute, dense spiral threads rendered granulose where crossed by even finer axial threads; protoconch II subsequent part sculptured by opisthocyrt axial riblets extending from suture to suture decussate by oblique threads on lower half of each whorl. Protoconch breadth: 0.66 mm. Teleoconch white, protoconch yellowish. Dimensions: Holotype 8.3 x 4.2 mm, aperture height 4.6 mm; Paratype: 8.8 x 4.1 mm, aperture height 4.5 mm.

Remarks: Acamptodaphne eridmata (fig. 1P) resembles A. biconica , from which it differs in its more broadly biconic shell (b/l 0.47–0.51 vs 0.41 according to measurements provided by Shuto, 1971), less concave sutural ramp, lower shoulder angulation on teleoconch whorls (fig. 1Q), absence of a developed basal fasciole and fewer protoconch whorls (2.75 vs 3.7) (figs. 1U–V).

Under SEM the surface of the labial callus of A. eridmata is characterized by a microsculpture of irregular linear corrugations with sharp edges (fig. 1S) rather than prickly granules as in A. solomonensis (fig. 1L). On one hand the observed difference between A. eridmata and A. solomonensis suggests that these microfeatures may be used in species differentiation, on the other the prickly granules occurring in A. solomonensis are also observed in species belonging to different genera. The systematic value of these microfeatures has not been adequately investigated. Their significance will probably be defined when enough species are known. Preliminary observations suggest that microscopic sculpture of the labial callus is widespread within different groups of “turrids”.

Etymology: Greek eridmatos (strongly built) refers to the solid shell of this species.