Siphonaria crenata Blainville, 1827

Jenkins, Bruce & Köhler, Frank, 2024, Hidden in plain sight: Systematic review of Indo-West Pacific Siphonariidae uncovers extensive cryptic diversity based on comparative morphology and mitochondrial phylogenetics (Mollusca, Gastropoda), Megataxa 13 (1), pp. 1-217 : 40-44

Siphonaria crenata Blainville, 1827

( Figs 14E–I, P, S–T, 18C–E)

Siphonaria crenata Blainville 1827b: 295 .— Hanley 1858b: 151; Paetel 1889: 428; Morrison 1972: 60 (unfigured and without descriptions).

Siphonaria rosea Hubendick 1943: 1 , pl. 1, fig. 1 (type locality: Insel Kharg, Persischer Meerbusen [Kharg Island, Persian Gulf, Iran]).— Hubendick 1945: 72; Galindo 1977: 416; Smythe 1979: 69; Christiaens 1980a: 81; White & Dayrat 2012: 67.

Siphonaria (Siphonaria) rosea — Hubendick 1946: 53, pl. 4, figs 12–15.

Material examined. Type material. Probable holotype of S. crenata Blainville, 1827 (type locality unknown; Savigny collection) ( MNHN IM 2000-35937 , Fig. 14E) .

Holotype of Siphonaria rosea Hubendick, 1943 from “Insel Kharg, Persischer Meerbusen” [ Kharg Island , Persian Gulf, Iran]; coll. G. Thorson, 1937 ( UUZM 1577 , Fig. 14H).

Other, non-type material. Saudi Arabia: Persian Gulf , 28°N, 50°E ( AM C.69719 d, Fig. 14I) ; Pakistan: Karachi , French Beach, 24°50.367’N, 66°49.387’E PA01- 1 ( AM C.585851 p [M242, SK233], Fig. 14G, C.585892 p [M239], C.595917 p [SK534]), PA01-2 ( AM C.585853 p, C.585338 p [SK153], Fig. 14F; C.585853 p [SK302]) .

Taxonomic remarks. Savigny (1817: pl. 1, figs 1–4; pl. 3, figs 1–5) published engravings without captions of two distinct siphonariids ( Fig. 14O–P herein) (see Bouchet & Danrigal, 1982 for bibliographic details). The first reference to Savigny’s figures appeared in Blainville (1825: 655): Under “et corrections” for the genus Siphonaria , he referenced Savigny’s figure (“ Ègypt. Gastéropod., pl.3, fig. 1–5”) [= S. crenata ] as ‘figured the animal of a species of this genus’ without assigning a name. Later, Blainville (1827b: 295) introduced the name S. crenata with reference to these figures stating “Savigny AEgypt. Zoolog.; Gastropodes, pl. 3, fig. 3–35.” without mentioning Savigny’s plate 1. Specimen 4 in the Savigny collection ( MNHN IM 2000-35937, Fig. 14E) resembles the specimen figured by Savigny (1817: pl. 3, fig. 3.5; Fig. 14P herein) with respect to shell edge and prominence of ribbing rather than any other of the figured shells.

Bouchet & Danrigal (1982: 15) mentioned three syntypes of S. savignyi to be held by the MNHN (most likely MNHN IM 2000-35934, Fig. 14L; 2000-35935, Fig. 14K; 2000-35936, Fig. 15J). The last two shells closely match in Savigny’s (1817) figures pl. 1, fig. 1 ( Fig. 15K) and pl. 1 figs 2–4 ( Fig. 14J) respectively. Our delineation of S. crenata is based on comparative analyses of the morpho-anatomy and mitochondrial genetics of freshly collected specimens of S. crenata ( Fig. 14F) and S. rosea ( Fig. 14G) and geographic series of additional specimens (Tables S1–2). Hubendick (1946: 50) listed among some ‘transitionalforms’inan‘Indian-WestPacificform-group’, a ‘ S. zanda <> S. rosea ’ form ( Hubendick 1946: 50, pl. 5, figs 1, 2). This shell is probably a specimen of ‘ S. rosea’ (= S. crenata , Figs 14E–F). Hubendick (1946: 54) proposed S. crenata to be a possible synonym of S. kurracheensis . However, type specimens of S. kurracheensis differ from Hubendick’s (1946: 54) interpretation of this taxon, and of the specimens from ‘Persian Gulf/Suez’ figured as ‘ S. kurracheensis ’ by Hubendick (1946: pl. 2, figs 36–40; except fig. 38 from ‘Java Sea’), are consistent with typical characteristics of S. crenata but not S. kurracheensis . A shell figured as ‘ Siphonaria savignyi ’ from Woody Point, Moreton Bay, Qld, Australia by Hubendick (1955: 2 ( MV F13951)) is a misidentification and attributed here to S. opposita . Morrison (1972: 61) stated that ‘ S. basseinensis’ mentioned by Tillier & Bavay (1905: 176) is a record of S. crenata ; however, this statement is not supported herein following examination of the type specimens of S. crenata ( Fig. 14E) and of S. basseinensis Melvill, 1893 ( Fig. 14M). This nominal species is not assessed in the present study. Morrison (1972: 56–58) treated Siphonaria rosea and 29 other nominal species as synonyms of Siphonaria laciniosa based on similarity in shell shape and “a common reproductive development”. These synonymies are not accepted herein following examinations of type specimens and comparative morpho-anatomy. Bouchet & Danrigal (1982: 15) incorrectly considered a shell figured by Reeve (1856: pl. 5, species 20) as S. kurracheensis to be identical with S. savignyi .

External morphology. Foot wall, pneumostome, cephalic folds and mantle evenly cream, foot edge paler, foot sole darker; faint black pigmentation over upper foot wall and mid centre of cephalic folds; mantle narrower than foot wall, thin translucent, white banded edge thickened strongly lobed, overlaid with black bands aligning to rib interstices; pneumostomal lobe thin and within mantle between the right ADMs, closes the pneumostomal and anal openings at the mantle edge; genital pore inconspicuous, located on foot wall posterior to right cephalic fold; two small black epithelial eye spots centralised on two thick centrally touching cephalic folds.

Shell ( Fig. 14E–G, T; Table S9). Medium to large sized (max sl mean = 15.2 mm, SD = 1.1, n = 4), ovate; height medium to low; apex offset sightly posterior and central (usually eroded), apical sides strongly convex, protoconch direction weakly heterostrophic (n = 2; Fig. 14T), shell whorl dextral; growth striae prominent in bands, shell thickness thick; rib count (mean = 32.3, SD = 1.1, n = 4), primary ribs pale white, fairly straight, increasingly raised and protrude beyond shell lip to unevenly scallop and corrugate the edge; 1–2 interspersed pale white finer secondary ribs, rib interstices darker; paired primary ribs on siphonal ridge, no more prominent than other primary ribs. Interior shell margin dark brown to tan, white rays align on shell margin under primary/ secondary ribs, siphonal groove distinct, same colour as shell edge, points to right anterior; spatula dark chocolate brown to mottled tan even whitish ( Fig. 14F–G); ADM scar distinct, CMS straight, paler than shell lip; thickening of shell lip translucent, infills and reduces lip scalloping, spatula becomes whitened.

Reproductive system ( Fig. 18C–E; n = 4). Positioned within right side of coelom, against foot wall on foot muscle, under the respiratory cavity; epiphallic parts positioned between RAM and BM; GA small indistinct with singular GP through foot wall; AO large wide bluntly pointed, joined to upper GA; ED short wide thickened, bent, joins to GA; GA, AO, ED all white muscular fibrous tissue; EG large, soft whitish tissue, folded, joins ED; single short flagellum (F1) shorter narrower than ED, lays over EG, appears as an extension of ED. BD and CD connect closely in opposing directions to GA between AO and GP, both ducts narrow elongated bent smooth whitish, pass together through RAM ( BD over CD) into soft white folded tissues of MG, BC partly embedded in folds, small flat bulbous, thin whitish translucent test (0 SPM in brownish gelatinous mass of BC); MG / AG complex relatively small; HD short narrow coiled, links ducts in soft white folded tissues of AG to yellowish granulated HG; AG / MG larger than HG, sides match curvature of inner foot wall.

Comparative remarks. Siphonaria crenata ( atra group, unit 43) is member of Clade H in the atra group ( Figs 1, 2) forming a subclade together with S. belcheri and S. madagascariensis . It is well-differentiated from other species by COI distances of ≥ 21.4% (Table S5). Within its range, we found four species in partial sympatry with S. crenata (e.g., in Karachi, Pakistan): Siphonaria asghar has a smaller, taller, paler shell with a less distinct siphonal ridge and weaker edge scalloping, smaller AO, shorter wider BD without distal loop, and a smaller BC. Siphonaria belcheri has a smaller, taller shell with less raised ribbing, weaker edge scalloping, darker reddishbrown interior, and slightly longer BD. Siphonaria kurracheensis has a smaller shell with less edge-protruding ribbing and weaker edge scalloping, and a smaller AO. Siphonaria perexigua sp. nov. has a smaller, taller shell with a less prominent siphonal ridge, less raised ribbing, weaker edge scalloping, a paler interior, smaller AO, longer ED, and a relatively larger BC.

Hubendick’s (1943: 3, fig. 9) illustration of the RS of S. rosea from the Persian Gulf corresponds well with the RS of S. crenata shown herein ( Figs 18C–E) in terms of having a long thin BD, short CD, large EG, short ED and F1, and a large, twisted AO. Moreover, figured shells of ‘ S. rosea ’ in Hubendick (1943: 1, fig. 1a–b, 1946: 91, pl. 4, fig. 12–15 from the same locality are consistent with typical features of S. crenata as herein delimited. Shells of ‘ S. savignyi’ figured in Hubendick (1946: 92, pl. 4, fig. 25–29) from ‘Port Tewfick, Red Sea’ and ‘ Gulf of Suez’ are also likely specimens of S. crenata . Figured specimens of ‘ S. kurracheensis ’ in Bosch et al. (1995: 186, fig. 863) and Ali et al. (2011: 1086, fig. 1B) are herein considered to represent S. crenata as well for corresponding shell size, ribbing, and extension of siphonal ridge.

Distribution and habitat. This species is recorded from the Red Sea and the Persian Gulf through to Karachi, Pakistan ( Fig. 28). In this study found in sheltered positions on exposed rocky intertidal shores, upper littoral level ( Fig. 14S).