Fulgurofusus maxwelli, Harasewych, 2011

Harasewych, M. G., 2011, The Living Columbariinae (Gastropoda: Neogastropoda: Turbinellidae) of New Zealand, Zootaxa 2744 (1), pp. 1-33 : 24-25

Fulgurofusus maxwelli , new species.

( Figures 97–116 , 118)

Diagnosis. Small to moderately sized species with fusiform shell, tall, conical, weakly stepped spire, weakly pentagonal aperture, long, axial siphonal canal. Protoconch nearly cylindrical, of 2–3 rounded whorls. Early teleoconch whorls with sharply angled shoulder, prominent peripheral keel, angular anterior carina becoming more rounded, less pronounced with increasing shell size. Teleoconch of up to 8 whorls. Peripheral keel low on whorls, well below midpoint between successive sutures. Spiral sculpture of numerous fine threads, cords, with adjacent cords along periphery forming incised furrow between them. Axial sculpture of low, weak ribs most pronounced at shoulder and anterior carina.

Description. Shell ( Figures 97–108 ) of moderate size (to 86.1 mm), stout, with tall, conical spire (spire angle 39–46˚), ovate aperture, long axial siphonal canal. Early whorls generally eroded. Protoconch ( Figures 111–112 ) tall, conical, nearly cylindrical, with rounded, heavily pitted whorls increasing in diameter from 495 µm to 1.7 mm in 2¾ whorls. First whorl deflected from coiling axis of shell by ~68˚. Transition to teleoconch marked by onset of strong shoulder, thin, spiral threads, sharp peripheral keel. Teleoconch extrapolated to consist of up to 8 angular whorls, becoming more rounded with increasing size. Suture ( Figure 102 , s) adpressed in smaller specimens, abutting spiral cord along anterior carina of previous whorl ( Figure 102 , ac) in larger specimens. Spiral sculpture of: fine threads or weak cords, 4–26 between suture and laterally expanded peripheral keel; 4–11 between peripheral keel and anterior carina; 4–6 between anterior carina and base of siphonal canal; up to 22 along proximal ½ of siphonal canal. Peripheral keel pronounced, with incised furrow along perimeter in early whorls, furrow reduced by 6 th postnuclear whorl, indistinct by 7 th postnuclear whorl. Axial sculpture of 10–14 wide, weak ribs most pronounced between periphery and anterior carina, producing broad undulating nodules along periphery. Aperture angular, irregularly pentagonal in juvenile specimens ( Figure 108 ), progressively more rounded with increasing size ( Figures 108 →101→105→97), deflected from shell axis by 24–29˚. Outer lip smooth, evenly glazed, weakly furrowed beneath peripheral keel, anterior carina, especially in early whorls. Spiral sculptural elements of preceding whorl wholly or partially resorbed prior to deposition of thin porcellaneous glaze along parietal region, columella, length of long, axial siphonal canal. Distal ⅓ of siphonal canal may be weakly spirally coiled. Shell surface generally eroded. Periostracum, where preserved, very thin, straw colored, weakly lamellose. Operculum ( Figures 109, 110 ) thin, elongated, weakly corrugated, with thickened edges, ovate attachment area, worn free end.

Gross anatomy of an immature female specimen ( Figures 101–104 , SL = 40.5 mm) generally similar to that of Coluzea spiralis . Radular ribbon of this specimen ( Figures 113–115 ) 2.52 mm long, with 96 rows of teeth. Rachidian teeth 54.5 µm wide, basal plate with U-shaped central section flanked by broad, expanded lateral edges. Three long, cylindrical cusps, central cusp longest (24.6 µm), confined to central 18.9 µm of tooth. Lateral teeth, each with single, long (51.4 µm), irregularly triangular, scythe-shaped cusp, attached to radular ribbon along a basal plate 19.9 µm wide.

Etymology. This new species honors the late Phillip A. Maxwell, for his prolific contributions to our knowledge of the invertebrate paleontology of New Zealand.

Type locality. ( Figure 116 ,) Campbell Plateau [53°30.6’S, 172°24.0’E] in 625 m, 22 Sep 1978, RV TANGA- ROA ( NIWA S48 ) .

Type material. Holotype, NIWA 67593 , 2 paratypes M 297055, USNM 1146128 , from the type locality. Additional Paratypes: 2 NMNZ M.297044, 1 NIWA S153 , northern Bounty Trough [45°21.2’S, 173°35.8’E], 1,386 m, 27 Nov. 1979, RV TANGAROA; 1 NMNZ M.297043, northern Bounty Trough [45°24.2’S, 173°59.8’E], 1,373 m, 27 Oct. 1979, RV TANGAROA; 2 NMNZ M. 297051, 1 NIWA I703 , Bounty Plateau [48°10.9’S, 178°15.9’E], 875 m, 21 Mar. 1979, RV TANGAROA; 6 NMNZ M. 297053, 5 NIWA I683 B, Bounty Plateau [48°18.5’S, 179°56.8’W], 516– 495 m, 15 Mar. 1979, RV TANGAROA; 17 NMNZ M. 297052, 18 NIWA I698 , Bounty Plateau [48°20.0’S, 178°30.0’E], 726 m, 19 Mar. 1979, RV TANGAROA; 2 NMNZ M.297042, 1 NIWA I697 , Bounty Plateau [48°29.1’S, 178°16.6’E], 917 m, 19 Mar. 1979, RV TANGAROA; 1 NMNZ M.297046, 1 NIWA I686 , Bounty Plateau [48°30.5’S, 179°45.0’W], 710 m, 16 Mar. 1979, RV TANGAROA; 2 NMNZ M. 297049, 2 NIWA I689 , Bounty Plateau [48°50.6’S, 178°41.5’E], 808– 608 m, 17 Mar. 1979, RV TANGAROA; 1 USNM 870882 , off Antipodes Island [49°40’S, 178°53’E], 476–540 m, 3 Jan. 1967, RV ELTANIN, sta. 1851 .

Additional material at NMNZ. 1 specimen , NMNZ M.284042, W of Chatham Islands [44°16.5’S, 178°31.6’E], 1148–1165 m, 8 Apr. 2007, RV TANGAROA .

Distribution ( Figures 116 , 118). Fulgurofusus maxwelli inhabits muddy bottoms along the northern Bounty Trough, the Bounty Plateau, and the eastern margins of the Campbell Plateau at depths ranging from 476 to 1,386 m, with a mean station depth [n = 11] of 862.7 m, and a confirmed bathymetric range of 516–1,386 m.

Remarks. The generic assignment of this new species is somewhat provisional. The tall, nearly cylindrical protoconch of nearly three whorls most closely resembles those of several species of Coluzea , among them Coluzea dentata , the type of the genus. The early teleoconch whorls manifest a prominent peripheral keel with an incised furrow along its perimeter that becomes nodulose as it intersects axial sculpture, a distinct anterior carina, and sculpture of multiple spiral cords, all features more characteristic of Fulgurofusus . In larger specimens the peripheral keel becomes reduced or absent, the anterior carina less pronounced, and axial ribs dominate the sculpture, resulting in a phenotype more characteristic of Peristarium Bayer, 1971, a subgenus of Fulgurofusus previously reported only from the Recent fauna of the tropical and temperate western Atlantic. Adult specimens of Fulgurofusus maxwelli more closely resemble Fulgurofusus (Peristarium) timor Harasewych, 1983 ( Harasewych 1983b: fig. 46–49) a species from comparable depths off Cape Fear, North Carolina, that any living or fossil New Zealand Columbariinae . Fulgurofusus maxwelli differs from F. timor in having a 3 whorled protoconch, more inflated whorls, and a weaker peripheral keel situated lower on the whorl. It also lacks the prominent spiral cords along the proximal portion of the siphonal canal and the incised furrow interrupted by axial nodes that are features of F. timor .

The geographic range of Fulgurofusus maxwelli overlaps slightly with that of Coluzea mariae along the southern margins of the Chatham Rise. However, the confirmed bathymetric range of F. maxwelli in this region is 1,165 – 1,386 m, compared to 128–687 m for C. mariae . These two species also occur on the Campbell Plateau. Coluzea mariae is known from the western portions of the plateau at depths of 360– 687 m. The type locality of F. maxwelli is along the eastern margin of the Campbell Plateau in 625 m.

Figures

FIGURES 97–115. Fulgurofusus maxwelli, new species. 97, Apertural, 98, lateral, 99, dorsal, and 100, apical views of the holotype, NMNZ M 297055, from the Campbell Plateau [53°30.6’S, 172°24.0’E], in 625 m. 101, Apertural, 102, lateral, 103, dorsal, and 104, apical views of a paratype from NMNZ M. 297051, Bounty Plateau [48°10.9’S, 178°15.9’E], in 875 m. 105, Apertural, and 106, dorsal views of paratype from NMNZ M. 297042, Bounty Plateau [48°29.1’S, 178°16.6’E], in 917 m. Arrow indicates unsuccessful attack by predator (probably a crustacean). 107, Dorsal and 108, apertural views of a paratype from NMNZ M. 297052, Bounty Plateau [48°20.0’S, 178°30.0’E], in 726 m. 109, Inner and 110, outer surfaces of operculum of the paratype in figures 101–104. 111, Lateral and 112, apical views of protoconch of paratype in figures 107–108. Arrows indicate transition to teleoconch. 113–115, Radular ribbon of paratype in figures 101–104. 113, 45° oblique view of radula. 114, Dorsal view with lateral teeth folded. 115, Dorsal view with lateral teeth expanded. ac, anterior carina; pk, peripheral keel; s, suture.

FIGURES 116–117. Geographic distributions of species of New Zealand Fulgurofusus. 116, Fulgurofusus maxwelli, new species. 117, Fulgurofusus marshalli, new species. Figures 118–119. Bathymetric distributions of species of New Zealand Fulgurofusus. 118, Fulgurofusus maxwelli, new species. 119, Fulgurofusus marshalli, new species. = type locality. = station records.