Siphonaria cacao, Jenkins, Bruce & Köhler, Frank, 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 : 168-169

publication ID	https://doi.org/10.11646/megataxa.13.1.1
DOI	https://doi.org/10.5281/zenodo.14989357
persistent identifier	https://treatment.plazi.org/id/0D49832F-FF3A-82B4-FCCA-FDC2FDF3FCF6
treatment provided by	Plazi (2025-03-05 09:04:49, last updated 2025-03-07 14:54:03)
scientific name	Siphonaria cacao
status	sp. nov.

Treatment

Siphonaria cacao View in CoL sp. nov.

( Figs 63M–O View FIGURE 63 , 64F–G View FIGURE 64 )

Material examined. Type material. Holotype, from Island of Tubuai, Austral Islands , 23°52’S, 147°41’E, IRD-MNHN Stn. X02 ( MNHN IM-2007-35319 p [SK506], Fig. 63M View FIGURE 63 ). GoogleMaps Two paratypes, same data as holotype ( MNHN IM-2007-35317 p [SK564], Fig. 63N View FIGURE 63 ; IM-2007-35318 p [SK565], Fig. 63O View FIGURE 63 ). GoogleMaps

Other, non-type material. Austral Islands : Tubuai, 23°52’S, 147°41’E, X02 ( MNHN IM-2007-35316 p) GoogleMaps .

External morphology (preserved). Animal exterior evenly cream, foot sole grey, paler to foot edge; mantle translucent, irregular widely spaced pigmentation spots on foot wall, concentrated over posterior and centre of cephalic folds.

Shell ( Figs 63M–O View FIGURE 63 ; Table S9). Small (max sl mean = 15.5 mm, SD = 0.5 mm, n = 3), circular ovate; height low; apex offset weakly left and strongly to posterior, apical sides straight to weakly convex; shell edge uneven; protoconch direction undetermined, shell whorl dextral; growth striae indistinct, exterior grey to pale brown and usually eroded, radial colour banding indistinct; shell thickness medium; rib count (mean = 38, SD = 1.6, n = 3), ~ 12 distinct uneven primary ribs, white to pale, fairly straight, rib growth uneven, ridges rounded, broaden to scallop and protrude beyond shell edge; 2–3 interspersed pale white finer secondary ribs, rib interstices darker; paired primary ribs form siphonal ridge, more prominent and extend shell edge further than at other primary ribs. Interior shell dark chocolate brown, shell lip thickened; paler uneven rays extend from the shell lip over the shell margin, align under primary/secondary ribs; spatula dark chocolate brown, maybe mottled blueish; siphonal groove clear, similar colour to margin and spatula; ADM scar distinct, CMS convex.

Reproductive system ( Fig. 64F; n View FIGURE 64 = 1). Positioned within coelom under the respiratory cavity, hermaphroditic glands positioned to posterior against right foot wall and over foot sole, epiphallic parts positioned to anterior tightly between RAM and over back of BM. Join of AO, ED and GA together at top of GA, AO larger than GA, elongated, bluntly pointed, centrally bent, thicker than ED; ED wide, centrally bent, shorter and narrower than AO; AO, GA and ED all muscular white tissue; EG folded, block-like, flagellum F1 small indistinct; BD and CD similar in thickness, connect side-by-side into GA, directly opposite to ED; both ducts smooth and pass together through outer side of RAM connecting into MG ( BD over CD), BC bulbous, embedded in MG / AG; hermaphroditic glands inaccessible.

Spermatophore ( Fig. 64G View FIGURE 64 ). Thread-like, test thin, translucent (incomplete); head section cylindrical (head length = 2.1 mm, n = 1), tip bulbous bluntly rounded, containing a white gelatinous core, smooth, featureless; 1 SPM tightly coiled embedded in white gelatinous mass in single BC.

Comparative remarks. Siphonaria cacao sp. nov. ( atra group) is the only species found in Tubuai in this study. We were unable to sequence COI or 16S from the available samples.

Distribution and habitat. Recorded exclusively from Austral Islands , French Polynesia, Pacific Ocean ( Fig. 67 View FIGURE 67 ). In this study, found on sheltered rocky shores (harbour at Island of Tubuai), intertidal.

Etymology. For the dark, chocolate-brown interior of the shell in this species; noun in apposition.

Figures

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.