Siphonaria capensis Quoy & Gaimard, 1833

(Figs 17L–N, 18F–G)

Siphonaria capensis Quoy & Gaimard 1833: 331, pl. 25, figs 32– 34 (type locality: Cap de Bonne-Espérance, baie de la Table [Table Bay, Cape of Good Hope, South Africa]).— Lamarck 1836: 561; Anton 1838: 26; Lamarck 1839: 206; Jay 1839: 39; Catlow & Reeve 1845: 100; Krauss 1848: 58; Dunker 1853: 3; H. Adams & A. Adams 1855 (in 1853–1858): 271; Hanley 1858b: 151; H. Adams & A. Adams 1863: 271; Paetel 1873: 117; 1883: 178; 1889: 429; Sowerby III 1892: 53; Bartsch 1915: 10; Turton 1932: 10; Hubendick 1947a: 163; Braga 1956: 7, pl. 1 fig. 1; Allanson 1963: 70; Galindo 1977: 416; Richards 1981: 79; Kilburn & Rippey 1982: 134, pl. 32, fig. 13; Villiers & Hodgson 1987: 129; Teske et al. 2007: 223, fig. 2; Pinchuck & Hodgson 2009: 371; Teske et al. 2011: 5026; White & Dayrat 2012: 61.

Siphonaria (Patelliopsis) capensis — Hubendick 1945: 70, fig. 20; 1946: 33, pl. 1, figs 40–42, pl. 2, figs 1–4; Allanson 1958: 150, 157, pl. 1, fig. 1; Chambers & McQuaid 1994a: 265, figs 1E, 3A; 1994b: 418; Chambers et al. 1996: 3; 1998: 51.

Siphonaria kowiensis Turton 1932: 10, pl. 4, 84 (type locality: Port Alfred, SA [South Africa]).— Allanson 1958: 166.

Siphonaria capensis var. lineolata Krauss 1848: 58, pl. 4, fig. 2 (type locality: Tafelbai [Table Bay, SA]); invalid, preoccupied by Sowerby I, 1835).—Sowerby III 1892: 54; Bartsch 1915: 10; Turton 1932: 10; Hubendick 1945: 19; 1947a: 163.

Siphonaria (Patelliopsis) capensis forma kraussi Hubendick 1946: 34, pl. 2, figs 1–4 (nom. nov. pro S. lineolata Krauss, 1848 not Sowerby I, 1835).— Allanson 1958: 159.

Pachysiphonaria capensis — Trew 1983: 2.

Siphonaria kraussi — White & Dayrat 2012: 59, 64.

Material examined. Type material. Lectotype of Siphonaria capensis Quoy & Gaimard, 1833, present designation, from ‘Cap de Bonne-Espérance, baie de la Table’ [Table Bay, Cape of Good Hope, South Africa] (MNHN IM 2000-38235 Fig. 17L); Seven paralectotypes, same data as lectotype (MNHN-IM-2000-5042).

Other, non-type material. Mozambique: Inhaca, Ponta do Farol, 25°58.2’S, 32°59.4’E MM6 (MNHN IM-2019-1477 p [M584], Fig. 17N; IM-2019-1481 p [M585], Fig. 17M) .

Taxonomic remarks. The lectotype is designated herein for the stabilisation of the name and to ensure the unambiguous identity of this taxon (Art. 74.1 of the Code). Krauss (1848: 58) introduced Siphonaria capensis var. lineolata; however, this name is preoccupied by S. lineolata Sowerby I, 1835 (Hubendick 1946: 33; White & Dayrat, 2012: 65) and S. lineolata Orbigny, 1841 (White & Dayrat, 2012: 65). Hubendick (1946: 33) introduced S. capensis forma kraussi as a replacement name. The taxonomic status of this taxon remains uncertain, but it is synonymized herein because of Hubendick’s treatment as an infrasubspecific taxon (forma). Hubendick (1946: 33) synonymized S. jonasii Dunker, 1846 (probably a juvenile), S. placentula Menke, 1853, and S. venosa Reeve, 1856 with S. capensis . He also attributed the record of ‘ S. pectinata ’ by Martens (1874) to S. capensis .

Our delineation of this species is based on comparative analyses of the morpho-anatomy and mitochondrial genetics of freshly collected topotypes (e.g., Fig. 17 M-N) and geographic series of additional specimens (Tables S1–2). The taxonomic status of S. placentula, S. oculus, S. venosa and S. jonasii has not been assessed herein. Therefore, Hubendick’s (1946) treatment of these taxa stands. Trew (1983: 2) incorrectly treated S. capensis as a synonym of S. funiculata .

Chambers & McQuaid (1994a, b) reported that S. capensis deposits benthic egg masses from which planktonic veliger larvae hatch.

External morphology (preserved). Animal yellowish/ cream. Irregular, widely spaced dark/black markings/spots along foot wall and cephalic lobes; genital pore conspicuous, located on foot wall posterior to right cephalic fold; mantle edge thick, large lobes.

Shell (Figs 17L–N; Table S9). Small to medium sized, ovate, thick, medium height (max sl mean = 23.1 mm, SD = 3.3 mm, n = 13), exterior grey/light brown, fairly even, apical sides convex, almost straight on posterior; apex offset to left and posterior, often eroded, protoconch direction undetermined, body whorl dextral, growth striae clear with faint external colour banding aligning with growth stages; primary ribs touching, raised fairly evenly spaced, straight, broaden to shell edge, ridges rounded to flat, rib count (mean = 42.6, SD = 5.8, n = 13), few to no secondary ribs; ribs project weakly beyond shell edge, siphonal ridge indistinct, weakly raised, formed by multiple ribs; rib interstices dark brown, weakly furrowed; shell edge weakly corrugated and scalloped. Interior glossy, edge and margin chocolate brown to black at shell edge with white /cream rays aligning under ribs, extending and narrowing from shell edge over margin to ADM scar, spatula pale blue/tan, siphonal groove apparent, same as interior colour, CMS straight.

Reproductive system (Fig. 18F; n = 3). Positioned within coelom under the respiratory cavity and intestine, over foot muscle, against right side of foot wall; epiphallic parts positioned over BM and between RAM; single conspicuous GP, opening from GA through foot wall posterior to right cephalic fold, junction of AO, GA and ED close distinct; AO large broad and flat, larger than GA, thicker than ED; GA bulbous proximal to ED and BD / CD junctions, ED relatively long and twisted; EG very large, broad, lobed, flagellum (F1) indistinct; BD and CD closely coupled, of similar length and thickness, connect in parallel close together into GA between ED and GP, BD without distal loop or MA; both ducts smooth, featureless, pass together partially through RAM connecting into soft curved folds of MG, CD wider and dorsal to BD; CD connects to small, bulbous, thin test BC, partially embedded into folds of MG; HD short thick, brown markings, coiled, links AG to elongated narrow yellowish granulated HD; HG larger than AG, MG and AG folded, soft white tissue; SV embedded on left side of AG.

Spermatophore (Fig. 18G). Very small, drop-like with short flagellum (length = 0.41 ± 0.037 mm, n = 3); head section bulbous, rounded (head length = 0.31 ± 0.04 mm, head ~76% of SPM length, head width = 230 ± 37 μm; flagellum width = 17 ± 0 μm, n = 3), body and flagellum test fur-like, opaque, tapering to a pointed end; both sections featureless; 4 SPM in brown gelatinous mass in one BC (MNHN IM-2019-1481 [M585]) embedded in white gelatinous mass.

Radula. Dentition formula: 42:1:42 (Hubendick 1946: 34).

Comparative remarks. Analyses of mtDNA sequences supported a sister relationship of S. capensis (unit 96) with unit 4 (= S. pectinata from Spain and Ghana + S. naufragum from Trinidad and Tabago; not reviewed herein, see Giribet & Kawauchi 2016). Distances between units 96 and 4 were ≥ 10.7% in COI (Table S8). We found two sympatric congeners in Mozambique: Siphonaria carbo has a darker shell with a more central apex and finer ribbing, an indistinct AO, larger, elongate BC and longer, larger SPM. Siphonaria plana has a smaller, paler shell with coarser ribbing and a flared siphonal ridge, smaller AO, twisted ED, BD with bursal and distal loops, a larger BC and a longer, thread-like SPM. For comparisons with South African siphonariids, such as S. serrata (Fischer, 1807), S. concinna Sowerby I, 1825, S. oculus Krauss, 1848 and S. carbo Hanley, 1858, which occur within the distributional range of S. capensis, refer to the studies of Allanson (1958), Chambers & McQuaid (1994a) and Teske et al. (2007, 2011).

The RS figured in Hubendick (1945: 18, fig. 20) closely resembles the RS of S. capensis figured herein (Fig. 18F) except for one detail in the junctions of the CD / BD / GP / GA, which Hubendick portrays as wider and with ducts more separated. Apart from the absence of an AO, the RS of S. capensis figured in Allanson (1958: 165, fig. 10) matches well the RS figured herein (Fig. 18F). Figured specimens of ‘ S. capensis’ and ‘ S. capensis v. kraussi’ in Hubendick (1946: pl. 1, figs 40–42 from Cape, South Africa; pl. 2, figs 1–4 from Port Natal, respectively) corresponds well with shells shown herein (Fig. 17L–N). Similarly, specimens figured in Krauss (1848: 58, pl. 4, fig. 2), Braga (1956: 7, pl. 1 fig. 1), Allanson (1958: 150, 157, pls 1a–b, 2a–b), Kilburn & Rippey (1982: 134, pl. 32, fig. 13) and Chambers & McQuaid (1994a: 256, figs1E, 3A) correspond well with typical features of this species.

Distribution and habitat. Endemic to SE coast of Africa (Fig. 28). During this study, collected on intertidal rocks in Baie de Maputo, Mozambique.