Siphonaria restis sp. nov.

(Figs 71D–H, O–P, 72B–D)

Siphonaria kurracheensis — Knox 1955: 88; Roberts & Wells 1981: 72, pl. 30, figs 142, 143; Black & Johnson 1981: 79; Jenkins 1983: 28; 1984: 117; Wells 1984: 54; Johnson & Black 1997: 104; Chim & Tan 2009: 269; Willan et al. 2015: 330 (not S. kurracheensis Reeve, 1856).

Siphonaria luzonica — Hubendick 1955: 3, fig 3; Hodgkin et al. 1966: 27, pl. 8, fig. 3 (not S. luzonica Reeve, 1856).

Siphonaria sp. — Verco 1912 b: 205; Wells & Bryce 1997: 379.

Material examined. Type material. Holotype, from Chinamans Rock, 27°42.776’S, 114°09.361’E, Kalbarri, WA; coll. B.W. Jenkins, WA52-1, 20 Nov 2017 (WAM S74049 [M400], Fig. 71D).

Paratypes same as holotype (WAM S74079 6p, S74048 p [M100], Fig. 71E, AM C.584731 11p, C.585200 p [M313], Fig. 71F, C.585919 p [SK150], Fig. 71G) .

Other, non-type material. Australia, WA: Chinamans Rock, Kalbarri, 21°54.739’S, 113°58.706’E; coll. B.W. Jenkins, WA52-1, 20 Nov 2017 (WAM S74047 p [M099], Fig. 54D, S 4078 p [SK050]); Thompson Bay, Rottnest Is, RI 012 (AM C.585201 p [SK381], Fig. 54E, C.585202 d [SK382], C.595909 d [R2004]); Tantabiddi, 21°54.739’S, 113°58.706’E, WA42-1 (AM C.585656 5p, WAM S74045 p [SK036]); Cape Latouche Treville nr Gourdon Bay, 18°27.101’S, 121°48.911’E, WA27-2 (AM C.584687 5p, WAM S74135 5p); 18°27.457’S, 121°48.725’E, WA27-1 (AM C.584711 5p, WAM S74136 2p); Cape Keraudren, 19°57.393’S, 119°46.358’E, WA29-2 (AM C.584704 5p, WAM S74138 2p); Withnell Bay Dampier, 20°35.106’S, 116°47.252’E, WA33-1 (AM C.584752 5p, WAM S74141 5p); Point Samson, 20°36.655’S, 117°11.472’E, WA32- 2 (AM C.584781 8p, WAM S74140 8p); 20°36.684’S, 117°11.303’E, WA32-1 (AM C.584751 5p, WAM S74139 5p); Dampier Hbr, 20°39.920’S, 116°42.134’E, WA33- 3 (AM C.585575 3p); Gnoorea Point, 1 20°50.560’S, 116°21.804’E, WA36-1 (AM C.584689 3p, WAM S74142 2p); Beardon Pt Onslow, 21°37.860’S, 115°06.573’E, WA37-1 (AM C.584722 5p, WAM S74143 4p); NW Cape Exmouth, 21°48.360’S, 114°07.665’E, WA41-1 (AM C.584698 6p, WAM S74144 3p); Fly Island, Great Sandy Islands, 21°48’19.548’‘S, 114°33’9.36’‘E (WAM S97276 p); Tantabiddi, 21°54.739’S, 113°58.706’E, WA42-1 (AM C.584690 5p, d; WAM S74145 2p); Pt S of Bruboodjoo Pt Bateman Bay, 23°02.991’S, 113°49.371’E, WA43- 1 (AM C.584732 12p, WAM S74146 5p); Point Maud, 23°08.322’S, 113°46.294’E, WA44-1 (AM C.584753 5p, C.585919 p [SK150], WAM S74147 5p); Coral Bay, S of Exmouth Gulf, 23°08.322’S, 113°46.294’E (AM C.595919 p [SK004], C.959956 p [SK001]); N of Point Quobba, 24°26.288’S, 113°24.204’E, WA45-2 (AM C.584727 7p, WAM S74149 5p); Point Quobba, 24°29.124’S, 113°24.501’E, WA45-1 (AM C.584754 5p, WAM S74148 5p); Bottle Bay Cape Peron, 25°32.566’S, 113°29.467’E, WA49-1 (AM C.584755 5p, WAM S74150 5p); Islet off Eagle Bluff, Shark Bay, Peron Peninsula, 26°05.5’S, 113°34.4’E (WAM S72339 6p); Whalebone, 26°07.835’S, 113°38.391’E, WA47-2 (AM C.585657 5p); Kells Rock Shark Bay, 26°10.473’S, 113°12.415’E, WA50-3 (AM C.584734 12p, WAM S74151 6p); Pepper Point (Zuytdorp), 26°23.826’S, 113°18.268’E, WA51-1 (AM C.584725 6p, d, WAM S74152 6p); Chinamans Rock, Kalbarri, 27°42.776’S, 114°09.361’E (AM C.585489 p [M053], C.585490 p [M398], C.585491 p [M399], C.585920 p [SK151]); Red Bluff, 27°44.627’S, 114°08.576’E, WA52-2 (AM C.595908 p [M125], C.585365 p [M126]); Horrocks, 28°21.469’S, 114°24.751’E, WA53-1 (AM C.584680 2p; WAM S74153 2p); Turtle Bay East Wallabi Is, 28°25.804’S, 113°44.538’E, WA55-1 (AM C.584758 5p; WAM S74155 5p); Houtman Abrolhos Islands, 28°25.804’S, 113°44.538’E (AM C.595971 2p), S of Fish Point East Wallabi Is, WA55-2 28°25.816’S, 113°44.633’E (AM C.584720 7p; WAM S74156 2p); Cape Burney Geraldton, 28°52.084’S, 114°38.056’E, WA54-1 (AM C.584749 5p; WAM S74154 5p); Leander Point Port Denison, 29°16.568’S, 114°54.858’E, WA57-1 (AM C.584760 5p, WAM S74157 5p); S end Leander Point Port Denison, 29°16.725’S, 114°54.918’E, WA57-2 (AM C.585517 d); Freshwater Point, 29°36.256’S, 114°58.464’E, WA57-3 (AM C.584693 3p, C.585009 p [SK063], WAM S74158 2p); Illawong Bch rocks, 29°42.198’S, 114°57.551’E, WA57-4 (AM C.584683 2p, WAM S74159 2p); Illawong, 29°42.254’S, 114°57.542’E, WA57-5 (AM C.584694 3p; WAM S74160 2p); Jurien Bay, 30°17.244’S, 115°02.482’E, WA58-1 (AM C.584679 2p; WAM S74161 p); Grey, 30°39.968’S, 115°08.072’E, WA58- 2 (AM C.585366 p); Cape Leschenault, 31°17.508’S, 115°27.089’E, WA58-3 (AM C.584712 5p, WAM S74162 5p); Quinns Rock, 31°39.822’S, 115°41.345’E, WA58- 4 (AM C.585368 p); Longreach Bay Point, Rottnest Is, 31°59.333’S, 115°32.063’E RI01 (AM C.585600 4p, C.585198 p [M311], C.585199 p [M312], C.585200 p [M313], C.584943 p [SK154], Fig. 71H); Point Brown Swan River, 32°02.344’S, 115°45.471’E, WA59-5 (AM C.585369 p [M128]); Fremantle Hbr, breakwater, 32°03.342’S, 115°43.987’E, WA58-5 (AM C.585519 d); Yallingup, 33°38.358’S, 115°01.481’E, WA60-9 (AM C.584724 6p, WAM S74163 5p); Cowaramup Point, 33°51.934’S, 114°58.904’E, WA60-3 (AM C.585370 p); Sarge Bay Cape Leeuwin, WA60-4 (AM C.585809 p); Yanchep, sheltered limestone cliffs, 34°32.783’S, 115°37.962’E (AM C.595972 p) .

External morphology (Fig. 71O). Foot wall usually without irregular black blotches, may be weakly present in some individuals; edge, pneumostomal lobe and cephalic folds all evenly brownish yellow, without any black/darker pigmentation markings, foot sole maybe dark brown/grey, foot edge paler; mantle translucent to transparent, as wide as foot wall, weakly lobed, aligns with undulations of primary shell ribs; the mantle edge thickened with yellowish band, may show dark pigmentation markings aligned with rib interstices; pneumostome wide between right adductor muscles and within mantle; cephalic folds thickened.

Shell (Figs 71D–H, P; Table S9). Medium sized (max sl mean = 17.5 mm SD = 2.7 mm, n = 19); height low to medium; ovate; apex central, apical sides weakly convex; protoconch direction weakly homostrophic (n = 1, Fig. 71P), shell whorl dextral, protoconch area distinctly darker brown; growth lines distinct; rib count (mean = 42, SD = 8.7, n = 19), weakly raised pale white to cream, weakly extend beyond shell edge, rib interstices dark brown; 10–12 evenly spread primary ribs; siphonal ridge prominent raised rounded, formed by 3 primary ribs; shell lip uneven, scalloped. Interior shell lip cream with brown splashes aligning with rib interstices, paler than shell margin, ADM scar prominent; spatula cream sometimes bluish; shell lip often golden brown with dark brown markings flanking shallow golden brown siphonal groove; CMS weakly concave, similar but darker colouration to spatula and shell margin; thickening of inner shell lip and spatula occurs in larger specimens, whitening covers brown colouration of inner shell lip.

Reproductive system (Figs 72B, D; n = 2). Positioned within right side of coelom,against foot wall on foot muscle, under the respiratory cavity; epiphallic parts positioned between RAM and BM. GA relatively small, with singular GP through foot wall; AO medium sized, broad, bluntly pointed, central bend, joined to upper GA; ED elongated, broad, centrally twisted, joins to side of GA; GA, AO, ED all white muscular fibrous tissue; EG medium sized, soft whitish tissue, slightly folded, joins at junction of end of ED and extension of single broad long flagellum (F1), end often looped; BD and CD connect closely together into GA between ED join and GP, both ducts long, slightly bent, smooth, narrow, whitish, featureless, pass closely together through outer side of RAM (BD over CD) into soft white folded tissues of MG; MG / AG complex large; CD connecting to ducts, BD without distal loop, often with loop or fold immediately in front of BC; BC embedded in MG folds, close to embedded SV; BC medium, thin whitish translucent test; HD distinct, short, coiled, links ducts in soft white folded tissues of AG to yellowish granulated HG; outer edge of MG lobbed; AG and HG of similar size, sides match curvature of inner foot wall.

Spermatophore (Fig. 72C). Thread-like, test thin, translucent (length = 6.38 ± 3.71, n = 3), flagella incomplete, head section cylindrical, tip bulbous bluntly rounded, containing a white gelatinous core, tapers into the filamentous transparent flagellum, both sections smooth, featureless, head much thicker than flagellum (length = 5.90 ± 3.02, n = 3, ~71% of SPM length, head width = 119 ± 33 μm, n = 3), two SPM embedded in brown gelatinous mass in one bursa (AM C.584943).

Radula (Figs 83I–L). Dentition formula 32:1:32 (n = 1, AM C.320123); single central rachidian tooth short broad, flanked squarely by 32 half row laterals, 10 are inner, 6 mid and 16 outer laterals; number of transverse rows not counted; central tooth short wide with short unicuspid mesocone; inner laterals (without endo or ectocones) prominent, mesocones of inner and mid laterals bicuspidate (Figs 83I–L), mid laterals with broad pointed ectocone; outer, laterals typically with a ‘chisel’ shaped mesocone, often weakly bicuspidate, flanked by small, pointed single ecto and endocones, angle of separation of each cone from the mesocone varies and maybe inwardly curved (Fig. 83K).

Comparative remarks. Siphonaria restis sp. nov. ( atra group, unit 54) forms a well-differentiated lineage in clade G of the mitochondrial tree (Figs 1, 2). It differs from other species by COI distances of ≥ 21.8% (Table S4). Throughout its range, we found S. restis sp. nov. in sympatry with seven congeners. Two are species are sympatric in south-western WA: For comparisons with S. stowae and S. jeanae refer to comparative remarks under these species. Three are sympatric in northern WA: For comparisons with S. atra, S. viridis, and S. gemina sp. nov. refer to comparative remarks under these species One species is sympatric in western WA: Refer to comparative remarks under S. zelandica . The RS figure of ‘ S. luzonica’ in Hubendick (1955: 3,fig 3) from Rottnest Is, corresponds well with the RS of S. restis sp. nov. shown here (i.e., parallel junction of BD and CD into GA, relative size of AO and twist in BD close to BC, Fig. 72B), and not that of S. sipho, the senior synonym of S. luzonica .

Distribution and habitat. Recorded as endemic to western and northern coasts of WA, Indian Ocean (Fig. 73). In this study, commonly found in sheltered positions on moderately exposed rocky shores, at upper and mid littoral levels.

Etymology. From the Latin ‘restis’ meaning ‘cord’— referring to the cord-like primary ribs on the shell of this species.