Siphonaria madangensis, B. W. Jenkins & Köhler, 2024

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 : 160-162

Siphonaria madangensis sp. nov.

( Figs 63A–B , 64C–D )

Material examined. Type material. Holotype, from S Dumduman Is, Rempi Area , Madang, PNG Coll. PNG 2013, PM12, 9 Nov. 2012 ( MNHN IM-2013-12006 [M550], Fig. 63A ) . Paratype, from Sek Island 05°04,7’S, 145°48,9’E, Madang, PNG; coll. PNG 2013, PM22, 14 Nov. 2012 ( MNHN IM-2013-13132 p [M552], Fig. 63B ) .

External morphology (preserved). Foot sole grey, paler to foot edge; foot wall, mantle and cephalic lobes darker grey; mantle edge band pale grey with darker markings aligning under rib interstices.

Shell ( Figs 63A–B ; Table S9). Circular ovate, small sized (max sl mean = 12.1 mm, SD = 1.8 mm, n = 2); shell thin, height low to medium; apex offset central, apical sides straight to weakly convex, protoconch direction undetermined, shell whorl dextral; growth striae indistinct, radial banding apparent, shell edge even thin, weakly scalloped; rib count (mean = 55.5, SD = 2.5, n = 2), ribs white, straight, fairly even, weakly raised to unraised, interstices dark brown; siphonal ridge clear, formed by dual split primary ribs, extends beyond shell edge; 0 to 2 secondary ribs between primary ribs; interior golden brown, dark brown rays aligned under rib interstices, span from shell edge to ADM scar, spatula golden brown to chocolate brown, siphonal groove clear, shallow; CMS weakly convex; no whitening or thickening of shell lip observed.

Reproductive system ( Fig. 64C; n = 1). Positioned within coelom under the respiratory cavity, occupies the right side of coelom, hermaphroditic glands positioned to posterior against right foot wall and over foot sole, epiphallic parts positioned to anterior between BM and RAM; GA small, with singular GP through foot wall; AO indistinct; ED short, broad, joins to side of GA; GA, AO, ED all white muscular fibrous tissue; EG small, soft whitish tissue, slightly folded, joins ED; single short broad flagellum (F1), similar length and width to ED, appears as an extension of ED. BD and broader CD with juxtapose connections into GA between ED / AO joint and GP, both ducts smooth, broad, whitish, featureless, pass closely together through outer side of RAM ( BD over CD) into soft white folded tissues of MG; BD without distal loop or prominent MA, centrally twisted; BC embedded in folds of small MG close to small pale embedded SV; BC medium sized, elongated, whitish translucent test; MG / AG complex relatively small; outer edge of MG lobbed; HD elongated, narrow, coiled, links ducts in soft white folded tissues of AG to small granulated HG; AG larger than HG, side reflects curvature of inner foot wall.

Spermatophore ( Fig. 64D ). Wide thread-like (length = 1.08 mm, n = 3), translucent, test thin; head section looped, pointed to bluntly rounded, bulbous cylindrical, containing a white gelatinous core, tapers along the transparent flagellum to a thin tip; both sections smooth, featureless, head section longer wider than flagellum (head length = 0.82 ± 0.14 mm, ~ 77% of SPM length, head width = 92 ± 10 μm, flagellum width = 17 ± 0 μm, n = 3). 4 SPM tightly coiled in brown gelatinous mass in single BC ( MNHN IM-2013-13132).

Comparative remarks. In our mitochondrial tree ( Figs1 , 4 ), S. madangensis sp. nov. ( normalis group, Clade E, unit 88) is most closely related to S. fuliginata (unit 80) from Rodrigues. Both species differ by COI distances of ≥ 5.9%. Siphonaria madangensis differs from S. normalis by COI distances of ≥ 5.6%. Siphonaria fuliginata has a paler shell with weaker scalloped edge, white to golden brown interior, a larger AO, a wider BD with bursal loop, and a thinner SPM. We found S. madangensis sp. nov. in sympatry with three congeners in northern PNG. For comparisons with S. atra , S. viridis , and S. normalis refer to comparative remarks under these species.

Distribution and habitat. Recorded from S Dumduman and Sek Islands, Madang area, northern PNG ( Fig. 67 ). In this study, found on limestone shores, intertidal.

Etymology. Named after the type locality of Madang, northern PNG.

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 4. Maximum Likelihood phylogram (partial, species not collapsed). Clades C–F (normalis, lateralis and pectinata 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 63. Shells of S. madangensis sp. nov., S. maloensis sp. nov., S. mauiensis sp. nov., S. nusalikensis sp. nov. and S. cacao sp. nov. A–B. S. madangensis sp. nov. A. Holotype MNHN IM-2013-12006 [M550]. B. Paratype IM-2013-13132 [M552]. C–F. S. maloensis sp. nov. C. Holotype IM-2007-31454 [M545]. D. Paratype IM-2007-31358 [M546], Sek Is. E. Paratype IM-2007- 31355 [M547], Palikulo Peninsula. F. Paratype IM-2007-31353 [M548], Palikulo Peninsula. G–K. S. mauiensis sp. nov., Maui, Hanakao’o Beach. G. Holotype AM C.584888 [M297, SK208]. H. Paratype AM C.584891 [SK207]. I. Paratype AM C.584890 [SK245]. J. Animal. K. In situ. L. Holotype of S. nusalikensis sp. nov. IM-2013-55334 [M532]. M–O. S. cacao sp. nov., French Polynesia, Tubuai. M. Holotype IM-2007-35319 [SK506]. N–O. Paratypes IM-2007-35317/18. Unlabelled scale bars = 10 mm.

FIGURE 64. Reproductive morphology of S. mauiensis sp. nov., S. madangensis sp. nov., S. nusalikensis sp. nov. and S. cacao sp. nov. A–B. Holotype of S. mauiensis sp. nov. AM C.584888 [M297, SK208]. C–D. S. madangensis sp. nov. Paratype MNHN IM-2013-13132 [M552, SK507], PNG, Sek Is. E. Holotype of S. nusalikensis sp. nov. MNHN IM-2013-55334 [M532]. F–G. Holotype of S. cacao sp. nov. MNHN IM-2007-35319 [SK506, EPI part only). Unlabelled scale bars = 1 mm.

FIGURE 67. Known occurrence records of S. madangensis sp. nov., S.maloensis sp.nov., S. mauiensis sp. nov., S.namukaensis sp. nov., S. nusalikensis sp. nov. and S. cacao sp. nov.