Siphonaria lirata Reeve, 1856

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 : 96-98

Siphonaria lirata Reeve, 1856

( Figs 35J–N, R, T–V , 36F–H )

Siphonaria lirata Reeve 1856 : pl. 7, species 35 (type locality unknown). Hanley 1858b: 152; Hedley 1915: 751; Cernohorsky 1972: 210; Galindo 1977: 416; Trew 1983: 8; White & Dayrat 2012: 65; Dayrat et al. 2014: 267.

Material examined. Type material. Lectotype of Siphonaria lirata Reeve, 1856 , present designation, without locality ( NHMUK MC.1979028/1, Fig. 35J ). Three paralectotypes, same data as lectotype ( NHMUK MC.1979028/2-4, Figs 35K–M ).

Other, non-type material. Guam: Pago Bay , below UoG Marine Lab , 13°25.645’N, 144°47.927’E, GM04- 1 ( AM C.585890 3p, C.584885 p [SK251]); Coast W of Piti Bay , Apra, 13°27.879’N, 144°40.762’E, GM03-1 ( AM C.585889 10+p, C.585192 p [SK252], C.585832 p [M448, SK242], C.585833 p [M449, SK162]) .

Taxonomic remarks. The largest syntype ( Fig. 35J ) is herein designated as the lectotype of S. lirata for the stabilisation of the name (Art. 74.1 of the Code). Reeve (1856: Erratum) clarified a mistake in labelling pl. 7, fig. 35: The correct name is S. lirata and not S. fuliginata . No type locality has been given in the original description of Reeve (1856). However, examining freshly collected from Guam revealed a shell form that closely resembled the features of the syntypes. Our delineation of this species is based on comparative analyses of the morpho-anatomy and mitochondrial genetics of freshly collected specimens from Guam ( Fig. 35N ) and geographic series of additional specimens (Table S1).

Pilsbry (1920b: 379) and Cernohorsky (1972: 210) incorrectly considered S. lirata as a synonym of S. normalis . Both Hubendick (1946: 23) and Jenkins (1981: 2) incorrectly treated S. lirata as a synonym of S. funiculata .

External morphology. Exterior evenly grey, paler grey to cream at foot edge and inner foot wall, foot sole darker grey; irregular black blotches of pigmentation on foot wall, pneumostomal lobe and concentrated over front of cephalic folds; mantle translucent, covers shell mantle, wider at anterior, outer edge thickened, weakly lobed with black bands of pigmentation aligning with rib interstices; pneumostomal lobe small, under mantle between the right anterior and right posterior ADMs, closes the pneumostomal and anal openings at the mantle edge; two small black epithelial eye spots centralised on centrally touching cephalic folds; genital pore inconspicuous, located on foot wall to right anterior of right cephalic lobe.

Shell ( Figs 35J–N, V ; Table S9). Small sized (max sl mean = 9.6 mm, SD = 0.6 mm, n = 3), ovate, height medium; apex offset posterior and to left; apical sides convex, posterior concave to straight; protoconch direction heterostrophic (n = 2; Fig. 35V ), area black colouration, shell whorl dextral; growth striae weak; shell thickness thin; colouration uneven with some radial banding; rib count (mean = 66.7, SD = 7.3, n = 3); slightly raised, pale white, fairly straight, faintly protrude beyond shell lip; predominantly primary ribs, finer secondary ribs interspersed, develop between primary ribs with shell growth, rib interstices darker; siphonal ridge formed by paired primary ribs, protrudes past shell edge, otherwise indistinct. Interior evenly dark brown to black from margin to spatula, paler on shell lip aligning under rib ends, siphonal groove clear; ADM scar indistinct, CMS weakly convex; No evidence of growth variations in shell thickness or shell margin colouration was observed.

Reproductive system ( Figs 36F,G; n = 2). Positioned within coelom under the respiratory cavity, hermaphroditic glands positioned to posterior against right foot wall and over foot sole, epiphallic parts positioned over and looped/folded in front of BM and to side of RAM; AO large, elongated, bluntly pointed (embeds into MG), centrally bent with MA, merges with indistinct GA; ED relatively short, slightly twisted, thick with side appendage; EG relatively large, folded, elongated and pointed; single short narrow bent flagellum F1 on EG; AO, GA and ED all muscular white tissue; BD and CD opposing connections (bulbous at CD) into GA between ED, AO and GP; BD longer and narrower than CD with a prominent distal loop, top of loop attached via a short MA to inner foot wall in front of BM, both ducts smooth and pass together through RAM connecting into folds of MG ( BD above CD), BC translucent test, midsized and bulbous; HD brownish long coiled links AG to a small elongated narrow brownish finely granulated HG; MG and AG small folded soft white tissue; dark SV embedded within AG, AG larger than HG, sides match curvature of inner foot wall at right posterior quarter of coelom.

Spermatophore ( Fig. 36H ). Thread-like, test thin, translucent; head cylindrical, very narrow, tip bluntly rounded, containing a white gelatinous core; taper region into the filamentous transparent flagellum is extended; both sections smooth, featureless; head longer and much thicker than flagellum (head length = 5.09 mm, n = 1, head width = 66.6 μm, flagellum width = 13 μm, flagellum incomplete); 1 SPM tightly coiled in a white gelatinous mass in one BC ( Fig. 36H ).

Comparative remarks. Siphonaria lirata ( plicata group, unit 58) is the sister species of S. tanguissonensis sp. nov., also from Guam ( Figs 1 , 3 ). Both species differ from each other by COI distances of ≥ 11.6% (Table S7). Siphonaria lirata differs from S. monticulus by COI distances of ≥ 15% and from other species by ≥ 21% (Table S7). Siphonaria lirata has been found in sympatry with three congeners in Guam. For comparison with S. guamensis and S. normalis refer to comparative remarks under these species. Siphonaria tanguissonensis sp. nov. has a lower, darker shell with a paler, golden brown/ tan interior, a smaller AO, and larger ED. Species with similar shell forms are S. mauiensis sp. nov., S. normalis ), S. exulum , and S. incerta . Previous records of ‘ S. lirata ’ from southern Australia are based on misidentifications of S. funiculata , which has a somewhat similar shell.

Distribution and habitat. Endemic to Guam ( Fig. 37 ). In the present study found on rock platforms and boulder areas on exposed rocky shores, mid to upper littoral levels ( Fig. 35T ).

Figures

FIGURE 1. Maximum Likelihood phylogram based on analyses of a concatenated sequence data set of 16S and COI. Branches are collapsed at the species level. Branch labels give unit numbers and accepted species names. Numbers on branches indicate branch support employing 10,000 ultrafast bootstraps.Available genus-group names are shown next to their type species. Scale bar indicating modelled sequence divergence.

FIGURE 3. Maximum Likelihood phylogram (partial, species not collapsed). Clades J–L (laciniosa and plicata groups) of the tree shown in Fig. 1. Branch labels give specimen identifiers for new sequences or Genbank accession numbers for imported sequences from other studies and geographic regions (see Tables S1–S2 for details). Identical haplotypes are merged into single tips. Numbers on branches indicate branch support by employing 10,000 ultrafast bootstraps. Clade names give unit numbers and accepted species names. Scale bar indicating modelled sequence divergence.

FIGURE 35. Shells of S. bifurcata, S. fuliginata and S. lirata. A–F, O–P, S. S. bifurcata. A. Lectotype NHMUK 1979169/1. B–D. Paralectotypes NHMUK 1979169/2-4. E. Philippines, Cebu, TS, AM C.585118 [M414, SK097]. F. Philippines, Polillo Is, TS, WAM S74096 [SK073]. O. Animal & P. Cebu, in situ. S. Protoconch, WAM S74098 [SK410]. G–I, Q. S. fuliginata. G. Holotype NHMUK 1981002. H. Rodrigues, AM C.585194 [SK369]. I. Rodrigues, AM C.585874 [M430, SK134]. Q. Rodrigues, in situ. J–N, R, T–V. S. lirata. J. Lectotype NHMUK 1979028/1. K–M. Paralectotypes NHMUK 1979028/2-4. N, R. Guam, Apra. N. AM C.585832 [M448, SK242]. R. AM C.585192 [SK252]. T–U. Guam, in situ. V. Protoconch,AM C.585833 [M449]. Unlabelled scale bars = 10 mm.

FIGURE 36. Reproductive morphology of S. bifurcata, S. fuliginata and S. lirata. A–C. S. bifurcata. A. Philippines, Polillo Is, TS, WAM S74096 [SK073]. B. Polillo Is, TS, WAM S74097 [SK412]. C. Cebu, TS, AM C.585118 [M414, SK097]. D–E. S. fuliginata, Rodrigues. D. AM C.585874 [M430, SK134]. E. AM C.585194 [SK369]. F–H. S. lirata, Guam, Apra. F. AM C.585832 [M448, SK242]. G–H. AM C.585833 [M449, SK162]. Scale bars = 1 mm.

FIGURE 37. Known occurrence records of S. bifurcata, S. fuliginata, S. lirata, S. exulum, S. belcheri, S. nuttallii, S. incerta and S. tasmanica