Taranis Jeffreys, 1870

Morassi, Mauro & Bonfitto, Antonio, 2013, Three new bathyal raphitomine gastropods (Mollusca: Conoidea) from the Indo-Pacific region, Zootaxa 3620 (4), pp. 579-588 : 580-583

Genus Taranis Jeffreys, 1870

(= Fenestrosyrinx Finlay, 1926 )

Type species: Trophon moerchii Malm, 1861

Remarks: Jeffreys (1870) proposed the genus Taranis for Trophon moerchii Malm, 1861 a recent species described from Sweden. According to Appeltans et al., 2012 (World Register of Marine Species, accessed at http:// www.marinespecies.org) the genus is represented in the recent fauna by 21 species and 2 subspecies with a worldwide distribution. Bouchet & Warén (1980) provided photographs of the type species and other northeast Atlantic Taranis species while the Indo-Pacific members of the genus were treated by Powell (1967). Kilburn (1991) reported the genus Taranis from southern Africa and described new species. Additional “typical” members of the genus Taranis recognized in literature are Taranis aliena (Marwick, 1965) from the Pliocene of New Zealand (Maxwell, 1988; Beu & Maxwell, 1990), T. circumflexa (Hornung, 1920) from the Pliocene-Early Pleistocene of Italy and Spain (Bernasconi & Robba, 1984; Vera-Peláez, 2002; Della Bella & Scarponi, 2007) and T. dellabellai Tabanelli, 1997 from the Pleistocene of Italy (Tabanelli, 1997; Della Bella & Scarponi, 2007). Beu (2011) has recently referred to Taranis the Australian Pliocene Fenestrodaphne pulchra Powell (1944) , type species of the genus Fenestrodaphne Powell, 1944 , the Recent Daphnella tasmanica Tenison-Woods, 1877 (Tenison-Woods, 1877; Hedley, 1922) and Hemipleurotoma esperanza May, 1911 both from Tasmania, and Daphnella vestalis Hedley, 1903 from Australia (Hedley 1903; 1922; Laseron, 1954). In addition to these species, Micantapex ? tomuiensis MacNeil, 1960, from the Miocene or Pliocene Okinawa, resembles members of Taranis in dimensions and sculpture and may prove to belong to this genus. Morphologically Taranis is characterized by species with a minute to small shell sculptured by (usually few) spiral cords crossed by axial ribs, which tend to form small nodules where they crossed the spirals, and a peripheral, very shallow anal sinus. Casey (1904) proposed the tribe Taranini to allocate Taranis while Powell (1966; 1967) referred the genus to subfamily Turrinae because of the peripheral position of the anal sinus, classification followed by Bernasconi & Robba (1984). Based on the absence of the radula and the reduction of several features of foregut anatomy, Kantor & Sysoev (1989) elevated Casey’s (1904) tribe Taranini to subfamily status. This classification has been used, although reluctantly, by many authors (Kilburn, 1991; Taylor et al., 1993; Vera-Peláez, 2002; Della Bella & Scarponi, 2007; Figueira & Absalão, 2010). Bouchet & Rocroi (2005) regarded the subfamily Taraninae as a synonym of Raphitominae Bellardi, 1875 , a synonymy confirmed by subsequent research (Bouchet et al., 2011; Puillandre et al., 2011). In their revision of northeast Atlantic Turridae, Bouchet & Warén (1980) referred the recent Pleurotomella ( Gymnobela ?) tornata var. malmii Dall, 1889 , a species with multispiral, diagonally-cancellate protoconch, to Taranis . However, as noted by Kilburn (1991), the latter species is morphologically much closer to the German early Miocene Magnella andersoni Dittmer, 1960 , type species of the genus Magnella Dittmer, 1960 than to Taranis moerchii and its inclusion in Taranis needs confirmation. Treated as a synonym of the genus Mioawateria by Maxwell (1988), Magnella has recently been retained as a full genus by Bouchet et al. (2011) and Figueira & Absalão, 2012. Beu (pers.com.) informed us that the late P.A. Maxwell discovered undescribed Taranis species bearing a multispiral protoconch with decussate sculpture from the Eocene of New Zealand. Furthermore, there is at least one undescribed recent species from Solomon Islands which has “typical” Taranis teleoconch characters but a multispiral raphitomine protoconch (pers. obs.). These observations provide conclusive conchological evidence that Taranis belongs to the Raphitomidae . Beu (2011) stated that “many extra-New Zealand species assigned to Mioawateria Vella, 1954 are actually species of Taranis with a tall, diagonally cancellate, planktotrophic raphitomine protoconch and a wide sutural ramp, and Mioawateria is possibly simply a synonym of Taranis ”. Compared to Mioawateria , species of Taranis are much smaller (most species are less than 5 mm in maximum length), differ in shape (fusiform-biconic instead of biconic to broadly biconic), lack a developed “moniliform” subsutural fold and have a distinctive sculpture frequently of lamellar ribs. Actually species belonging to Taranis show as adult morphological features those encountered in juvenile specimens of some species belonging to Mioawateria and to the widely distributed genus Gymnobela Verrill, 1884 . It seems quite possible that Taranis represents a paedomorphic genus within the Raphitomidae but this hypothesis needs to be validated. The somewhat borderline position of Pleurotomella ( Gymnobela ?) tornata var. malmii Dall, 1889 should not lead to disregard of the numerous morphological differences between Taranis and Mioawateria which, in our opinion, warrant recognition these as two distinct taxa, at least until objective evidence demonstrates the contrary. The new species described below is of interest as it represents the first typical Taranis species described from the Gulf of Aden. In fact, the littoral Taranis allo (Lamy in Jousseaume, 1934) described from Djibouti is a doubtful member of Taranis (Kilburn, 1991) .

Taranis adenensis sp. nov. Fig. 1.A–G

Type material: Holotype (MZB49753), 14 paratypes (one coated) (MZB49754), 1 paratype (MNHN25731) and 1 paratype (ZMA.MOLL.408924)

Type locality: Gulf of Aden (Indian Ocean), stn RED SED 92/1, 11º55'95"N, 44º22'70"E to 11º55'82"N, 44º22'53"E, 795– 810 m.

Material examined: 17 dd from Gulf of Aden, stn RED SED 92/1, from 11º55'95"N, 44º22'70"E to 11º55'82"N, 44º22'53"E, 795–810 m (holotype and 14 paratypes MZB, 1 paratype MNHN, 1 paratype ZMA); 1 dd from Gulf of Aden, stn RED SED 92/2, between 12º02'36"N, 44º29'53"E and 12º02'46"N, 44º30'82"E, 1395–1400 m (MZB49759).

Description: Shell broadly biconic (b/1 0.56–0.73; a/1 0.45–0.56) with well produced base, curving strongly to left and rather blunt, orthoconoid spire. Teleoconch of about 3¼ whorls with deep but not channeled suture bordered below by a narrow cord. Sculpture of spiral cords, of which the peripheral one forms a prominent keel, crossed by narrow axial ribs, forming small, sharp nodules in intersections with spirals (particularly on the peripheral cord) ( Fig. 1.D ). Axial ribs much narrower than their intervals, somewhat variable in strength, angularly arcuate and slightly opisthocline, extending on base but not onto neck. There are 15–17 axial ribs on later two teleoconch whorls. Spiral sculpture with a peripheral cord at mid-whorl; a weak thread develops at level of suture on second whorl increasing in strength on last whorl. In some specimens a third weak cord develops between the two main cords on last whorl. Base of last whorl with 2 widely spaced cords and, in some specimens, a third very faint cord, 4 weak threads on the neck. Under SEM surface is seen to bear a microsculpture of minute, spirally aligned pustules (fig. 1.E). Aperture somewhat oblanceolate strongly bent at siphonal canal. Siphonal canal short, slightly curved to the columella. No labial callus. Outer lip thin, with very shallow and broad anal sinus, its apex on peripheral cord. Protoconch domed, depressed, of 1 whorl with minute, dense granulous spiral threads ( Fig. 1.F–G ). Protoconch diameter: 0.24–0.30 mm. Translucent white (when fresh). Dimensions: Holotype 2.4 x 1.6 mm, aperture height 1.1 mm; largest paratype: 2.8 x 1.8 mm, aperture height 1.4 mm; smallest paratype: 1.8 x 1.1 mm, aperture height 0.8 mm.

Etymology: adenensis , alluding to the fact that the new species is described from the Gulf of Aden.

Remarks: T. adenensis sp. nov. is morphologically very similar to T. borealis Bouchet & Warén, 1980 , described from the Koster Islands ( Sweden) but can be readily separated mainly on the basis of the protoconch features. The protoconch is white in Taranis adenensis sp. nov. whereas it is brown in T. borealis . Furthermore, in Taranis borealis there are distinct axial threads crossing the spiral threads giving the protoconch a reticulate appearance whereas the protoconch of T. adenensis sp. nov. shows no trace of reticulation resembling that occurring in other members of the genus such as T. moerchii Malm, 1861 and T. dellabellai Tabanelli, 1997 . The new species has weaker and possibly fewer spiral cords on base (usually 2 rather than 3 distinct cords as in T. borealis ) and an additional (though inconstant) spiral cord between the main two cords on last whorl. Taranis adenensis sp. nov. is similar in shape and protoconch features to the Italian Pleistocene T. dellabellai but the latter is distinguished in possessing a peripheral cord below mid-whorl and more numerous, stronger spiral cords on shell base (four versus two). As stated above, Taranis moerchii resembles the new species in protoconch characters but the latter has a more biconic shape and fewer spiral cords and axial ribs. Micantapex ? tomuiensis MacNeil, 1960 from the Tertiary of Okinawa may resemble Taranis adenensis sp. nov. in shape but otherwise differs distinctly in being much larger (7 mm vs 1.8–2.8 mm) with a strong nodulous peripheral keel. Taranis adenensis sp. nov. is a very small species, none of studied shells that appear to be of adult specimens exceed 2.8 mm in length and have more than 3¼ teleoconch whorls. In its minute dimensions the new species resembles T. laevisculpta Monterosato, 1880 (Bouchet & Warén, 1980) but otherwise differences in sculpture are obvious. Taranis adenensis sp. nov. represents the smallest described member of the genus Taranis in the Indo-Pacific region.

Figures

FIGURE 1. A – G. Taranis adenensis sp. nov. A. Holotype, scale bar 800 μm, Gulf of Aden, stn RED SED S 92 / 1 (MZB 49753); B – G. Paratype, Gulf of Aden, stn RED SED 92 / 1 (MZB 49754); B. Frontal view, scale bar 600 μm; C. Apical view, scale bar 400 μm; D. Penultimate whorl, scale bar 200 μm; E. Surface microsculpture, scale bar 40 μm; F – G. Protoconch, scale bar 100 μm. H – N. Mioawateria vivens sp. nov. H. Holotype, 6.3 x 3.3 mm, Gulf of Aden, stn RED SED 92 / 1 (MZB 49755); I – N. Paratype, Red Sea, stn RED SED 92 / 4 (MZB 49756); I. Frontal view, scale bar 1 mm; J. Apical view, scale bar 1 mm; K – L. Protoconch, scale bar 100 μm; M. Detail of protoconch I, scale bar 50 μm; N. Surface microsculpture, scale bar 50 μm. O – T. Holotype of Awheaturris lozoueti sp. nov., Philippines, AURORA 2007 stn CP 2682 (MNHN 25730); O. Frontal view, scale bar 1 mm; P. Apical view, scale bar 1 mm; Q. Penultimate whorl, scale bar 500 μm; R. Surface microsculpture, scale bar 80 μm; S – T. Protoconch, scale bar 200 μm.