ALISIMITRA FUSCOLINEATA

ALISIMITRA FUSCOLINEATA

( HERRMANN & SALISBURY, 2012) COMB. NOV.

FIGURE 14D – F View Figure 14

Vexillum (Costellaria) fuscolineatum Herrmann & Salisbury, 2012: 133 – 138 View in CoL ; figs 36 – 39.

Type data

Holotype: MNHN IM-2000-25190, TARASOC, station DW3425, 16 ° 43 0 S, 151 ° 03 0 W, 557 m, French Polynesia, Society Islands , Huahine, dd, 17.3 mm ( Fig. 14D, E View Figure 14 ). GoogleMaps

Paratypes: Paratypes 1 – 5 listed by Herrmann &

Salisbury (2012).

Material examined

Type material from French Polynesia; TARASOC, station DW3429, 16 ° 43 0 S, 150 ° 38 0 W, 493 – 540 m, French Polynesia, Society Islands , Huahine, 1 lv (MNHN IM-2007-39271, Fig. 14F View Figure 14 ) GoogleMaps .

Diagnosis

Shell fusiform, of medium size, measuring up to 22 mm in height. Protoconch conical, with about three brown glossy whorls. Teleoconch of seven or eight whorls. Spire orthoconoid, elongate, with gently convex whorls. Sculpture of narrow, orthocline axial ribs intersected by low, rounded spiral cords. Number of axial ribs increases from 9 – 11 on the first whorl to 15 – 18 on the penultimate whorl, and 24 – 34 on the last adult whorl; ribs becoming flatter towards last adult whorl. Two or three stronger and widely spaced spiral cords adapically, and finer and more closely set cords on rest of whorl surface. Spiral cords on shell base sometimes very weak or obsolete. Siphonal fasciole with between four and seven distinct oblique cords. Siphonal canal long, nearly straight in adult specimens. Aperture moderately wide, elongate, with thin outer lip smooth inside; inner lip with four columellar folds, adapicalmost strongest, succeeding folds progressively weaker. Protoconch brown, teleoconch white with narrow brown band slightly above periphery of spire and last adult whorls. Second, faint brown band may be present in lower part of last adult whorl.

Distribution and habitat

French Polynesia (Society Islands, 490–560 m, Tuamotu Archipelago, 500–800 m) and Hawaii (Oahu, about 370 m).

Remarks

In shell proportions and sculpture, Alisimitra fuscolineata is close to Alisimitra deforgesi sp. nov.; however, Alisimitra deforgesi sp. nov. is generally smaller and can be distinguished by the characteristic adapical ‘cap’ and variegated colour pattern. Alisimitra tehuaorum and Alisimitra barazeri sp. nov., although they have a proportionally shorter siphonal canal, are also close to Alisimitra fuscolineata ; both are uniformly pale or tan, whereas Alisimitra fuscolineata has a characteristic narrow brown band. Alisimitra fuscolineata also bears fine spiral cords throughout the shell surface, whereas in both Alisimitra tehuaorum and Alisimitra barazeri sp. nov. typically only an adapical cord is present.

GENUS COSTAPEX GEN. NOV. FEDOSOV, HERRMANN & BOUCHET

Type species: Costapex sulcatus sp. nov.

Diagnosis

Shell small, fusiform or widely fusiform. Protoconch cyrtoconoid with three or more evenly convex glossy whorls. Teleoconch with 4.5–7.0 evenly convex whorls. Sculpture on late teleoconch whorls dominated by spiral elements, some species may lack sculpture and single adapical spiral groove may be present. In contrast, earlier teleoconch whorls sculptured by coarse axial ribs. Siphonal canal rather long, straight, and tapering, or slightly recurved at its tip. Aperture rather wide, with evenly convex, sometimes slightly undulating, outer lip; inside of outer lip smooth or lirate within. Inner lip with three or four narrow columellar folds of equal or subequal strength. Head-foot massive, with light-brown or black bands on dorsal surface of foot. Eye tentacles moderately long, with large eyes situated at bases. Radula with rather broad tricuspidate rachidian and narrow unicuspidate sickle-shaped laterals. Gland of Leiblein large, glandular, brown. Males with seminal canal represented by open groove within mantle cavity, and closed along entire length of penis.

Included species

Costapex sulcatus View in CoL sp. nov., 1 † Costapex elatior (Finlay, 1924) , 2 Costapex exbodi View in CoL sp. nov., 1 Costapex joliveti ( Poppe & Tagaro, 2006) View in CoL , 2 Costapex levis View in CoL sp. nov., 1 Costapex margaritatus View in CoL sp. nov., 2 Costapex martinorum (Cernohorsky, 1984) View in CoL . 2

Distribution and habitat

Species of Costapex gen. nov. are recorded from the tropical western Pacific: Philippines, Papua New Guinea (Bismarck and Solomon Seas), New Caledonia. At least two species of Costapex gen. nov. have been collected from sunken wood.

Etymology

From the Latin costa (rib) and apex (top). The name Costapex refers to the characteristic sculpture of early teleoconch whorls.

Remarks

Because of the lack of axial sculpture on late teleoconch whorls or prevailing spiral sculpture, the overall appearance of Costapex species recalls deep-water Mitridae , rather than costellariids. The species of Costapex gen. nov. can be readily distinguished from mitrids by the presence of strong axial ribs on early teleoconch whorls. In all species of the Costapex gen. nov. the columellar folds are thin, of equal or subequal strength; this allows their easy recognition among other deep-water costellariids, which usually have the adapicalmost columellar folds notably stronger. The fine columellar folds and often small shells of some Costapex gen. nov. species also render them extremely close to the volutomitrid genus Microvoluta . The two genera, however, can be distinguished by the details of columellar folds: these are always rounded in Costapex gen. nov. and sharp in Microvoluta . In addition, the presence of a translucent, bulbous protoconch readily reveals the species of Volutomitridae .

Six living species, which we assign to the newly established genus Costapex sp. nov., can be separated into three morphologically distinct groups. The ‘lesser’ Costapex gen. nov. species, Costapex sulcatus sp. nov., Costapex Joliveti , and Costapex margaritatus sp. nov. ( Fig. 15), are characterized by small shells, which do not usually exceed 15 mm in height, and late teleoconch whorls dominated by spiral sculpture, whereas earlier whorls bear strong axial ribs. The ‘larger’ Costapex gen. nov. species, Costapex martinorum and Costapex exbodi sp. nov. ( Fig. 17F – I View Figure 17 ) are similar to the ‘lesser’ species in sculpture pattern, but are characterized by solid, notably larger shells that are intensely coloured brown. The third group, which can be referred to as ‘smooth’ Costapex is represented by the single species Costapex levis sp. nov. ( Fig. 17A – E View Figure 17 ), which is distinctive because of its smooth late teleoconch whorls.

COSTAPEX SULCATUS SP. NOV. FEDOSOV, HERRMANN & BOUCHET

FIGURE 15A – D

Type data

Holotype: MNHN IM-2013-40627, 08 ° 43 0 N, 123 ° 19 0 E, 259 – 280 m, Philippines, East of Aliguay Island , lv, 7.4 mm; Figure 15A, B. GoogleMaps

Paratype: MNHN IM-2000-31646, same locality as holotype, lv, 6.5 mm; Figure 15C.

Other material examined

Philippines: PANGLAO 2005, station CP2390, 9 ° 27 0 N, 123 ° 43 0 E, 627 – 645 m, Bohol Sea, 1 dd (3.9 mm); station CP2407, 9 ° 41 0 N, 123 ° 48 0 E, 256 – 268 m, Bohol Sea, Maribojoc Bay , 1 lv (MNHN IM-2007-30321, 9.4 mm) GoogleMaps .

Solomon Islands: SALOMON 2 , station CP2272, 8 ° 56 0 S, 157 ° 44 0 E, 380 – 537 m, New GoogleMaps Georgia Island, 1 dd (6.7 mm).

Vanuatu: SANTO 2006 , station AT99, 15 ° 06 0 S, 166 ° 51 0 E, 351 – 395 m, Big Bay , 2 lv (MNHN IM-2007-30254, 8.0 mm; MNHN IM-2007-30260, 9.3 mm, Fig. 15D) GoogleMaps .

Diagnosis

Shell small, fusiform, with orthoconoid spire and rather wide aperture. Protoconch pointed, with three or more convex, glossy whorls. Teleoconch whorls flattened in profile, sculptured with evenly spaced deep spiral grooves that have a dashed appearance; an adapical groove usually deeper and stronger than succeeding ones. Axial sculpture of strong, coarse axial ribs on early spire whorls and indistinct low folds on later whorls. Microsculpture of very fine, dense, collabral growth lines. Last adult whorl evenly convex, siphonal canal rather long, straight, tapering. Aperture wide, its outer lip thin, evenly convex throughout its length, smooth inside. Inner lip with five, fine, equal, oblique columellar folds. Seminal canal represented by an open groove on side of body, closed on penis. Radula with tricuspidate rachidian and narrow, sickle-shaped, unicuspidate laterals. Mid-oesophagus widened; gland of Leiblein well developed, large and brown.

Description

Shell small, thin-walled, fusiform (w / h 0.4; a / h 0.55). Protoconch (intact only in paratype 1; apex strongly corroded and protoconch missing in all other specimens) high, pointed, with about four smooth, convex whorls. Teleoconch with about 4.5 whorls, first two with rather adpressed profile; penultimate and last whorls slightly evenly convex. Suture deeply impressed. Sculpture of orthocline rounded axial ribs, more pronounced on first two whorls and becoming flat and indistinct on last adult whorl, and microsculpture of fine growth lines. Axial folds overridden by broad, flattened, slightly undulating spiral cords separated by widely spaced narrow grooves of somewhat ‘perforated’ appearance. Adapical spiral groove strongest, succeeding spiral grooves (four on each spire whorls) weak on second teleoconch whorl, distinct on penultimate whorl, and almost equal to adapical groove on last adult whorl. Six wide and flattened spiral cords on adapical portion of last adult whorl and periphery succeeded on shell base by six narrower and more rounded in profile cords, and six even narrower oblique cords, on siphonal canal. Siphonal canal rather long, straight, tapering. Aperture rather wide; outer lip thin, undulating, evenly convex; smooth inside. Inner lip with five distinct columellar folds of equal strength. Background colour pale, with very faint lighter spiral band on whorl periphery.

Anatomy (paratype)

External morphology: Body pale yellowish, with light-brown bands on foot. Operculum absent. Siphon simple, moderately long, slightly protruding beyond the mantle edge. Head bearing moderately long eye tentacles with large black eyes situated laterally at base ( Fig. 16A, B View Figure 16 ). Mantle cavity spanning ~ 0.7 whorl; mantle thin with mantle cavity organs clearly visible. Ctenidium very long, narrow, spanning throughout the posterior two-thirds of the mantle cavity. Osphradium large, exceeding one-half of ctenidium length. No distinct anal gland.

Anterior alimentary canal: Proboscis white, in contracted state occupying about two-thirds of the rhynchocoel length. Anterior rhynchodaeum thin, whitish, semi-translucent. Two distinct muscular bundles (retractors) attached laterally to anterior rhynchodaeum ( Fig. 16C View Figure 16 ). Buccal mass moderately long, situated in basal portion of proboscis. Oesophagus forming a loop after leaving the proboscis, lying dorsally, and entering medium-sized bulbous valve of Leiblein. Salivary gland large, white, unpaired, situated posterior to proboscis. Accessory salivary gland(s) not observed, possibly because of the minute size of dissected animal. Posterior oesophagus adjoined by brown bulky gland of Leiblein, which is massive in its anterior portion and notably extended backwards along the oesophagus.

Radula (of holotype; Fig. 16D View Figure 16 ): Radula 0.2 mm in length and about 0.04 mm in width, consisting of 58 rows. Rachidian tricuspidate with moderately wide base and long pointed cusps, which are set notably apart. Lateral teeth narrow, sickle-shaped, curved, with single pointed cusp.

Reproductive system: The paratype studied is male, with a moderately sized penis of subcylindrical (very slightly flattened) shape, without distinct papilla. Seminal canal indistinct on penis, and certainly not forming an open groove. The seminal canal is very distinct on the body of the animal, however: it is wide and represented proximally by an open groove.

Distribution and habitat

Philippines, Solomon Islands, Vanuatu. Alive in depths of 268 – 351 m. Holotype collected from sunken wood.

Etymology

The species name refers to the characteristic sculpture pattern of multiple spiral grooves (Latin sulcatus = grooved).

Remarks

Among known costellariids, Costapex joliveti ( Poppe & Tagaro, 2006) is closest to Costapex sulcatus sp. nov.: both have similar sculpture pattern and coloration, and are closely related based on our phylogenetic analysis; however, Costapex sulcatus sp. nov., being generally smaller and more elongate, is characterized by a smooth outer lip of the aperture, whereas it is lirate within in adult specimens of Costapex joliveti . Another ‘lesser’ Costapex species, Costapex margaritatus sp. nov., although close to Costapex sulcatus sp. nov. in proportions, has a notably stronger spiral sculpture, with subsutural and subsequent grooves developed equally. Overall, the dominating spiral sculpture elements of Costapex sulcatus sp. nov. make it look rather like a mitrid. A similar sculpture pattern of dashed spiral grooves is characteristic for some deep-water Mitridae : for example, the genus Calcimitra Huang, 2011 . Costapex sulcatus sp. nov., however, can be distinguished by the presence of strong axial ribs on early spire whorls.

Specimen MNHN IM-2013-4814 ( Fig. 15 E), despite sharing the same sculpture pattern, is characterized by rather biconical shell with much longer siphonal canal. This specimen comes out separately on the COI -based molecular tree, suggesting that it represents a separate species; however, with a single specimen at hand we are uncertain about the value of these morphological characters and we refrain from formally naming it here.

COSTAPEX JOLIVETI ( POPPE & TAGARO, 2006) View in CoL