The genus Siphonalia was originally established by Adams (1863) to accommodate several new species, and taxa previously described by Reeve (1846-1847). This genus currently includes more than 20 valid Recent species (see MolluscaBase, 2018), the majority of which occur along the coast of southern Japan (14 species, see Okutani, 2000) and five species from Chinese waters: S. cassidariaeformis (Reeve, 1846), S. callizona Kuroda & Habe, 1961 and S. nigrobrunnea Lee & Chen, 2010 from Taiwan Island; S. fusoides (Reeve, 1846) from the East China Sea and Taiwan Island; and S. spadicea (Reeve, 1847) from the Yellow and East China Seas (Wu and Lee, 2005; Zhang, 2008; Lee and Chen, 2010).
Recently, examination of Siphonalia specimens in collections of the Marine Biological Museum, Chinese Academy of Sciences, revealed three species, two of which proved undescribed, and one a new distribution record. Herein we describe and illustrate these species, increasing the recognized richness of Siphonalia taxa known from Chinese waters.2 MATERIAL AND METHOD
Specimens were collected from China seas (Fig. 1). Shell morphology was observed by stereomicroscope. A radula was extracted and cleaned with 10% NaOH at 60℃ for 4-5 h, washed in distilled water, air dried, and then coated with gold for examination by scanning electron microscopy. Specimens have been deposited at the Marine Biological Museum, Chinese Academy of Sciences (MBMCAS).
Abbreviation: MBM: Marine Biological Museum; RN: registration number; coll: collector; spm(s): specimen(s); stn: station.3 RESULT
Class Gastropoda Cuvier, 1797
Order Neogastropoda Wenz, 1938
Family Buccinidae Rafinesque, 1815
Genus Siphonalia A. Adams, 1863
Diagnosis. Species with moderate-sized, ovately fusiform shell; teleoconch whorls usually shouldered, sculptured with axial ribs and spiral cords; spire acute, body whorl ventricose; aperture ovate, siphonal canal recurved; operculum ovate with apical nucleus; radula formula 1+1+1, with tricuspid central tooth and lateral tooth with 3 or 4 cusps.3.1 Siphonalia marybethi Parth, 1996 (Fig. 2)
Distribution and habitat: Vietnam (Vung Tau); China (South China Sea), live at depths to 80 m, on sandy to muddy sediments.
Description: Shell (Figs. 2a-d) height to 46.7 mm, very thick, biconical, with acuminate spire; siphonal canal very short, slightly recurved. Protoconch of 1.5 smooth whorls; teleoconch to 6 evenly convex whorls. Body whorl rounded, large, occupying 3/4 of total shell length. Suture narrow, slightly channeled. Spiral sculpture of strong, raised cords, the subsutural one strongest; axial sculpture of prominent ribs, limited to spire whorl. Aperture ovate, outer lip internally crenulated. Columella weakly calloused, sigmoid. Anal canal present. Operculum ovate, with anterior nucleus. Shell color uniformly yellow, covered with thick, brown periostracum.
Preserved animal (Fig. 2e, g) yellowish. Tentacles short, stout, with near-centrally located eyes on outer margin. Siphon short, thick. Foot broad. Penis large, distal end with a conical seminal papilla.
Radula (Fig. 2f) rachiglossate. Central tooth nearly rectangular, posterior margin with three equal-sized cusps; lateral teeth with three large cusps, innermost short, wide, central smallest, outermost largest.
Remarks: Parth (1996) described this species on the basis of two empty shells from the South China Sea off Vung Tau, Vietnam. Our specimens from Hainan Island increase the recognized distribution of this species.3.2 Siphonalia leei sp. nov. (Fig. 3a-d)
Type specimens: Holotype, RN: MBM283602, Kueishan Island, Taiwan Island, China, on sandy bottom. Paratypes, three shells, RN: MBM283603, collected with holotype at type locality.
Type locality: Kueishan Island, Taiwan Island, China.
Etymology: The new species is named after Mr. Chin-Yeh Lee, who collected the type specimens.
Description: Shell (Fig. 3a-d) of medium size for genus, height to 35.1 mm, very thick, solid, with small, conical spire (spire angle ~50°) comprising about 1/3 total shell length. Body whorl very large, rounded, occupying 2/3 of total shell length. Protoconch rounded (maximum diameter 1.2 mm), of 1.5 smooth whorls, with indistinct transition to teleoconch, followed by initial axial ribs that become stronger and more regularly spaced after 1/4 whorl. Suture adpressed, slightly undulant. Teleoconch with up to 5 flattened whorls with distinct shoulder angulation. Spiral sculpture of 4 or 5 cords on first teleoconch whorl, and 7 or 8 on second whorl, without intercalated cords. Third and subsequent whorls with thin secondary peripheral spiral cord, developing into 5 cords on body whorl. Spiral cords raised, with flattened top, with moderately rectangular cross-section.
Axial ribs on spire whorls only, extending from suture to suture on earlier whorls, becoming broad and widely spaced toward the shell base, forming strong, rounded knobs on whorl periphery. First to fourth teleoconch whorls with 10 or 11, and penultimate whorl with 12 axial ribs, with microscopic incremental lines, forming fine axial grooves and ridges between spiral interspaces.
Aperture large, ovate, whitish within, offset from coiling axis by ~20°. Siphonal canal long, broad, open, deflected dorsally and adaxially, with prominent fascioles along its length. Outer lip slightly expanded, internally with 17 ridges of varied strength; columella lip smooth, with thick callus. Shell base color uniformly white under thick, brown periostracum. Operculum ovate, with apical nucleus.
Radula and soft parts unknown.
Remarks: Siphonalia leei sp. nov. is most similar to S. fusoides (Reeve, 1846-1847) and S. trochulus (Reeve, 1843) in general shape (see Reeve, 1846- 1847; Okutani, 2000). From S. fusoides it differs in having a relatively small spire with flattened profile, more recurved siphonal canal, and much smaller adult shell size, and from S. trochulus (Reeve, 1843) it differs in having angulate rather than rounded spire whorls, and a less ventricose body whorl.3.3 Siphonalia nanshaensis sp. nov. (Fig. 3e, f)
Type specimen: Holotype, RN: MBM116671, Nansha Islands (Spratly Islands): 5°16′N, 114°10′E, 173 m, on sandy bottom, 9 May, 1987.
Type locality: Nansha Islands (Spratly Islands), China.
Etymology: The name refers to its type locality, Nansha Islands.
Description: Shell (Fig. 3e, f) medium sized for genus, 45.5 mm long and 21.0 mm wide, very thick, solid, with tall, acute spire (spire angle ~40°) comprising 2/5 total shell length. Body whorl rounded, occupying 3/5 of total length, shell base abruptly constricted. Protoconch rounded (maximum diameter 1.0 mm), of 1.5 smooth whorls; transition to teleoconch indistinct, followed by indistinct axial ribs that become stronger and more regularly spaced after 1/5 whorl. Suture adpressed, undulant. Teleoconch with 7 convex whorls, sculptured with spiral cords and axial ribs. Spiral cords slightly undulant, rather raised, with flattened top and moderately rectangular cross-section, overriding but not nodulating the thick axial ribs. First, second and penultimate teleoconch whorls with 5, 7 or 8, and 10 spiral cords, respectively; body whorl with about 25 spiral cords; with occasional secondary spiral cords on periphery of the penultimate and body whorl.
Axial ribs extend from suture to suture on spire, becoming obsolete on lower part of body whorl. First teleoconch whorl with 10, and penultimate and body whorls each with 12 axial ribs. Incremental lines very weak, forming small axial grooves on spiral cords and weak ridges between spiral interspaces, giving shell surface a rough appearance.
Aperture ovate, yellowish within, offset from coiling axis by ~15°. Anal canal distinct, 2.5 mm in length. Outer lip thickened, with 14 ridges of varied strength, strongest posteriorly, becoming shorter and more rounded anteriorly; columellar lip smooth, moderately calloused. Siphonal canal long, narrow, open, strongly deflected dorsally and adaxially, with prominent fascioles along its length. Shell base color yellowish.
Radula and soft parts unknown.
Remarks: Siphonalia nanshaensis sp. nov. is most similar to S. mikado Melvill, 1888, but that species can be differentiated from it by having a more angulate teleoconch whorl with irregularly spaced spiral cords, less constricted shell base, and inner-lip with parietal teeth.4 DISCUSSION
Although the taxonomy of Siphonalia species has been well studied, systematic relationships between species would benefit from further revision. Descriptions of most species have been based on hard-part conchological features, without descriptions of radular and anatomical characters, or molecular data. The shape and arrangement of radular teeth (e.g. Cernohorsky, 1971; Bouchet and Warén, 1985), and anatomy of the male reproductive system (e.g. Golikov, 1963; Kosyan and Kantor, 2014, 2016), have proven useful in buccinid taxonomy. Various buccinid groups have also been classified based on the basis of mitochondrial and nuclear gene data (e.g. Hayashi, 2005; Nakano et al., 2010; Hou et al., 2013). Unfortunately, detailed information of anatomy and radular features, and molecular data are not available for the two new species described herein. To determine robust systematic relationships between species in this genus, further studies, which include examination of soft tissue at both morphological and molecular level, are needed.5 DATA AVAILABILITY STATEMENT
The authors declare that all the data supporting the findings of this study are available within the article.6 ACKNOWLEDGEMENT
We would like to express our sincere thanks to Koen Fraussen for his enthusiastic support and information. We also thank Steve O'Shea, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.
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