Teretia tavianii, Morassi, Mauro & Bonfitto, Antonio, 2015

Morassi, Mauro & Bonfitto, Antonio, 2015, New Indo-Pacific species of the genus Teretia Norman, 1888 (Gastropoda: Raphitomidae), Zootaxa 3911 (4), pp. 560-570 : 564-565

Teretia tavianii sp. nov.

Figures 2.A–G

Type material. Holotype ( MZB 60097) and two paratypes (paratype 1 MZB 60098 (coated); paratype 2 MNHN IM- 2000-28378).

Type locality. Gulf of Aden (Indian Ocean), 11º55'95"N, 44º22'70"E to 11º55'82"N, 44º22'53"E, 795–810 m], September 1992 [N/ O “Marion Dufresne”, RED SED 92, stn 1].

Material examined. Three dd (holotype and two paratypes) from the type locality.

Description. Shell ( Figs. 2.A–C ) widely fusiform (b/l 0.46; a/l 0.50) with high spire, strongly excavated base and relatively long anterior canal. Teleoconch up to about 3½ whorls, with shallowly impressed, linear suture. Subsutural ramp rather wide, concave. Spiral sculpture on first teleoconch whorl consisting of a prominent peripheral cord below mid-height of the whorl and two closely spaced weak spiral cords bordering abapical part of subsutural ramp (the abapical one much stronger). On subsequent whorls a second cord develops at level of abapical suture; last whorl with one spiral thread in the interpace between two cords. Adapical part of subsutural ramp with a weak spiral cord near suture. Last whorl with six and nine spiral cords on base and rostrum respectively. Teleoconch whorls sculptured by fine axial growth lines forming relatively strong, widely spaced, arcuate plicules on subsutural ramp, rendering somewhat nodulous the spiral thread bordering adapical suture. Under SEM, the surface is seen to be sculptured by microgranules ( Fig. 2.D ). Aperture lanceolate, outer lip thin. Anal sinus deep, narrow, asymmetrical, its deepest point on subsutural ramp ( Fig. 2.B ). Protoconch of three whorls; first whorl tilted with microgranules arranged in spiral rows, subsequent whorls with diagonally cancellate sculpture terminating a short distance above abapical suture where fine slightly prosocline riblets occur. Maximum diameter about 0.38 mm. Shell white, protoconch brown. Dimensions: Holotype 3.2 x 1.5 mm, aperture height 1.6 mm.

Remarks. Teretia tavianii sp. nov. differs from the Southern Africa Teretia acus ( Barnard, 1958) in having fewer, less prominent, spiral cords (two versus three on spire whorls) and in number of protoconch whorls (3 rather than 4½). T.tavianii sp. nov. differs from T. anceps and T. teres in possessing fewer, less prominent cords (two versus respectively 4–5 and 3–4 main cords on spire whorls; compare Figs. 2.C–D and Fig. 3.B–C ) and in protoconch features (compare Figs. 2.E–G with Figs. 3. D–F ). More in detail, T. tavianii sp. nov. has fewer protoconch whorls (3 rather than 4–4 ½) and while in the new species the diagonally cancellate sculpture tends to be restricted to whorl periphery, in both T. anceps and T. teres it occurs on whorl surface except for a narrow area near adapical suture (compare Fig. 2.E with Fig. 3.D ). Teretia fusianceps Nordsieck, 1972 is distinguished from T. tavianii sp. nov. in having more prominent spiral cords and a more narrowly fusiform shell.

Etymology. Named after Marco Taviani, Geologist of Institute of Marine Science, National Research Council ISMAR-CNR, that made possible the participation of the one of the authors (AB) to the cruise RED SED ’92.

Figures

FIGURE 2. A – G. Teretia tavianii sp. nov., Gulf of Aden, Cruise RED SED 92, stn RS 1. A – B. Holotype (MZB 60097), 3.2 x 1.5 mm. C. Paratype 1 (MZB 60098), penultimate whorl, scale bar 1 mm. D. Surface microsculpture of penultimate whorl, scale bar 200 µm. E – F. Protoconch, scale bar 200 µm. G. Details of protoconch 1, scale bar 50 µm. H – N. Teretia tongaensis sp. nov. H – N. Holotype (MNHN IM- 2000 - 28379), Tonga, Cruise BORDAU 2, stn DW 1553, 8.2 x 3.4 mm H – J. Frontal and lateral view of holotype, scale bar 2 mm L. Penultimate whorl, scale bar 500 µm. M. Microsculpture of penultimate whorl, scale bar 500 µm. N. Microsculpture of penultimate whorl, scale bar 100 µm. O – P. Protoconch, scale bar 200 µm.

FIGURE 3. A – F. Teretia teres (Reeve, 1844), Jonian Sea, from 39 ° 33.3 ’ N – 18 ° 04.7 ’ E to 39 ° 33.6 ’ N – 18 ° 54.5 ’ E, 1017 – 1060 m [N / O “ Bannock ”, Cruise J 74, stn 12] (MZB 11791). A. Specimen A, shell, 6.9 x 3.3 mm. B – F. Specimen B coated B. Penultimate whorl, scale bar 500 µm. C. Surface microsculpture of penultimate whorl, scale bar 100 µm. E – F. Protoconch, scale bar 200 µm. G. Details of protoconch 1, scale bar 100 µm. G. † Teretia elegantissima (Foresti, 1868), Italy, Calabria, Vallone Catrica (RC) (MZB 14856) H. Pleurotomella packardi Verril, 1872, Atlantic Ocean, Cruise BIOGAS, stn CP 37, 47 ° 34 ’ N – 08 ° 39 W, 2175 m.