Siphonaria diemenensis Quoy & Gaimard, 1833

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 : 44-48

Siphonaria diemenensis Quoy & Gaimard, 1833

( Figs 17C–G, O–Q , 20A–C )

Siphonaria diemenensis Quoy & Gaimard 1833: 327 , pl. 25; figs 1–12 (type locality: “le canal d’Entrecasteaux, à Île de van Diémen” [D’Entrecasteaux Channel, Tasmania]).— Lamarck 1836: 562; 1839: 207; Catlow & Reeve 1845: 100; Jay 1850: 104; H. Adams & A. Adams 1855 (in 1853–58): 271; Reeve 1856: pl. 1, species 4; Hanley 1858b: 151; H. Adams & A. Adams 1863: 271; Angas 1865: 189; Dall 1870: 31, 37; Tenison Woods 1877: 56; Hutton 1878: 42; Adcock 1893: 11; Tate & May 1901: 418; Pritchard & Gatliff 1903: 220; Verco 1907: 105; May 1921: 88; 1923: 87, pl. 41, fig. 2; Cotton & Godfrey 1932: 152, pl. 3, fig. 6; Macpherson & Chapple 1951: 142; Cotton 1959: 411; Macpherson & Gabriel 1962: 262, fig. 299; Burn & Bell 1976: 234; Mapstone 1978: 85; Jenkins 1981: 2; 1983: 29; Hochlowski & Faulkner 1983: 1917; Hochlowski et al. 1983: 7413; Trew 1983: 5; Capon & Faulkner 1984: 2506; Jenkins 1984: 113; Phillips et al. 1984: 78, text-fig; Quinn 1988: 115; Ludbrook & Gowlett-Holmes 1989: 610, fig. 11.29 l, m; Wilson 2002: 172, fig. 172; Grove et al. 2006: 60; Chim & Tan 2009: 270; Grove 2011: 62, pl. 29, fig. 13; White & Dayrat 2012: 62; Colgan & da Costa 2013: 74.

Siphonaria diemensis Anton 1838: 26 .— Menke 1844: 54; Paetel 1873: 117; 1883: 178; 1889: 428; Galindo 1977: 416 (invalid; incorrect subsequent spelling of diemenensis ).

Siphonaria diemanensis Tenison Woods 1878a: 46 ; 1878b: 99 (invalid; incorrect subsequent spelling of diemenensis ).

Siphonaria scabra — Angas 1867: 232 (not S. scabra Reeve, 1856 ).

Siphonaria atra — Angas 1867: 233 (in part) (not S. atra Quoy & Gaimard, 1833 ).

Siphonaria cochlearformis Whitelegge 1889: 117 (in part) (invalid; incorrect subsequent spelling of S. cochleariformis Reeve, 1856 , not S. cochleariformis Reeve, 1856 ).

Siphonaria diemenensis var. denticulata — Tenison Woods 1878a: 47; 1878b: 99; Tate & May 1901: 418 (not S. denticulata Quoy & Gaimard, 1833 ).

Siphonaria (Ductosiphonaria) diemenensis — Hubendick 1945: 70, figs 23, 28–29.— Hubendick 1946: 38, pl. 2, fig. 16.

Siphonaria (Ductosiphonaria) diemenensis var. diemenensis — Hubendick 1946: 38, pl. 2, fig. 16.

Siphonaria (Ductosiphonaria) diemenensis var. denticulata — Hubendick 1946: 38, pl. 2, fig. 17 (not S. denticulata Quoy & Gaimard, 1833 ).

Siphonaria (Ductosiphonaria) diemenensis var. scabra — Hubendick 1946: 38, pl. 2, fig. 14, 15 (not S. scabra Reeve, 1856 ).

Siphonaria (Ductosiphonaria) diemenensis var. macauleyensis — Hubendick 1946: 38 (not S. macauleyensis Oliver, 1915 ).

Hubendickula diemenensis — McAlpine 1952: 42; Cotton 1959: 411; Iredale & McMichael 1962: 82.

Siphonaria (Hubendickula) diemenensis — Ludbrook & Gowlett-Holmes 1989: 610, fig. 11. 29 l, m.

Siphonaria ‘unit 7’— Dayrat et al. 2014: 252, 258, 259, fig. 3 H; González-Wevar et al. 2018: 5.

Material examined. Type material. Lectotype of Siphonaria diemenensis Quoy & Gaimard, 1833 , present designation, from ‘le canal de d’Entrecasteaux, á l’ î le de van Diémen’ [ d’Entrecasteaux Channel , Tasmania] ( MNHN-IM-2000-35952 , Fig. 17C ) . Paralectotype, same data as lectotype ( MNHN-IM-2000-5059 ).

Other, non-type material. Australia, NSW: Terrigal, The Skillion, 33°27.008’S, 151°27.122’E, NSW08-2 ( AM C.585631 5p); Wy-ar-gine Point Balmoral, 33°49.159’S, 151°15.195’E,NSW06-5( AM C.585630 6p); Laings Point Sydney Harbour, 33°50.419’S, 151°16.638’E, NSW06- 3 ( AM C.585404 17p); Bombo Kiama, 34°39.232’S, 150°51.649’E, NSW03-1 ( AM C.585682 7p); Murunna Point Camel Head, 36°22.720’S, 150°04.766’E, NSW02- 1 ( AM C.585402 10p, C.585001 p [SK037]); Oman Point Eden, 37°04.634’S, 149°53.445’E, NSW01-1 ( AM C.585527 20+p). Vic: Bastion Head Mallacoota, 37°34.429’S, 149°45.927’E, V09-1 ( AM C.585611 4p); Cape Conran, 37°48.798’S, 148°43.608’E, V08-2 ( AM C.585543 20+p, C.585293 p [M196]); Frankston , 38°09.236’S, 145°06.457’E, V06-1 ( AM C.585356 p); Point Lonsdale (nr Queenscliff), 38°17.276’S, 144°36.977’E, V05-1 ( AM C.585436 10p); Port Fairy , 38°23.692’S, 142°14.260’E, V01-1 ( AM C.585694 7p); Roadknight Point, 38°25.707’S, 144°11.102’E, V04- 1 ( AM C.585716 8p, C.585286 p [M168], C.585287 p [M169]); WestHeadFlinders, 38°28.883’S, 145°01.727’E, V06-3 ( AM C.585542 20+p, ( AM C.585290 p [SK003], C.585291p [M198]); Loutit Bay Lorne, 38°31.190’S, 143°59.429’E, V03-2 ( AM C.585541 20+p); San Remo, 38°31.489’S, 145°21.858’E, V07-1 ( AM C.585357 p [SK029]); Crofts Bay , 38°35.363’S, 142°50.633’E, V01-3 ( AM C.585680 6p); Marengo Rocks Apollo Bay , 38°46.772’S, 143°39.997’E, V03-1 ( AM C.585433 10+p). Tas: Georges Bay , Burns Bay , 41°16.62’S, 148°28.92’E ( TMAG E41975 3p); Beaumaris, Shelly Point, 41°26.136’S, 148°16.638’E ( TMAG E41965 4p); Denison Beach, Porch Rocks, 41°47.334’S, 148°16.158’E ( TMAG E41963 2p); Bicheno, 41°52.837’S, 148°18.525’E, T02-1 ( AM C.585692 7p); Bicheno Courland Bay , 41°55.866’S, 148°18.414’E ( TMAG E41960 p); Swansea Spiky Beach, 42°11.142’S, 148°4.104’E ( TMAG E41961 7p); Louisville, Alginate Bay , 42°32.4’S, 147°54.6’E ( TMAG E24490 p); Maria Island , Darlington Bay , 42°34.8’S, 148°3.6’E ( TMAG E16769 2p); Maria Island , Hopground Beach, 42°35.4’S, 148°3.6’E ( TMAG E08499 3p); Earlham, foreshore, 42°39.6’S, 147°57’E ( TMAG E08098 6p); Dodges Ferry, 42°51.083’S, 147°36.981’E, T03-1 ( AM C.585428 10+p); Dodges Ferry, Red Ochre Beach, 42°51.6’S, 147°36.6’E ( TMAG E08843 p); Park Beach, Dodges Ferry, 42°51.716’S, 147°36.665’E, T03-4 ( AM C.585260 p [M170], C.585261 p [SK016]); Carlton Beach, Spectacle Island , 42°52.044’S, 147°36.024’E ( TMAG E41955 4p); Primrose Sands, 42°53.4’S, 147°40.2’E ( TMAG E04957 p); Lauderdale, Roches Beach, 42°54.6’S, 147°0.3’E ( TMAG E03265 p); Lagoon Bch (near Saltwater River ), 42°56.903’S, 147°39.962’E, T03-2 ( AM C.585253 p [SK015], C.585254 p [SK185]); Taroona Beach, 42°57.18’S, 147°21’E ( TMAG E41969 14p); Kingston Beach, 42°58.8’S, 147°19.2’E ( TMAG E02012 p); Eaglehawk Neck, eastern side, 43°0.6’S, 147°0.6’E ( TMAG E01661 3p); Blackmans Bay , 43°0.6’S, 147°19.8’E ( TMAG E15878 8p); Saltwater River , 43°01.083’S, 147°43.578’E, T03-11 ( AM C.585725 7p); Tasman Arch, 43°02.033’S, 147°56.963’E, T03- 3 ( AM C.585771 5p, C.585256 p [M175], C.585257 p [M176]); Pirates Bay , Fossil Island , 43°1.8’S, 147°57’E ( TMAG E01299 p); Tinderbox Beach, 43°3.6’S, 147°19.8’E ( TMAG E05223 3p); North Bruny Island , Dennes Point, 43°3.87’S, 147°21.066’E ( TMAG E41968 3p); Nubeena, Parsons Bay , 43°6’S, 147°6’E ( TMAG E05994 p); Kettering, Oyster Cove, 43°6.6’S, 147°16.2’E ( TMAG E05350 3p); Nubeena, White Beach, 43°7.2’S, 147°43.8’E ( TMAG E06016 p); North Bruny Island , Simmonds Bay , 43°7.8’S, 147°21.6’E ( TMAG E02677 2p); Fortescue Bay , 43°8.4’S, 147°57.6’E ( TMAG E05581 2p); Three Hut Point d’Entrecasteaux Channel, 43°16.195’S, 147°14.414’E, T04-3 ( AM C.585482 18p, C.584797 p [SK047], C.585269 p [M112]); Huon Point d’Entrecasteaux Channel, 43°17.471’S, 147°05.778’E, T04-1 ( AM C.585430 10+p); South Bruny Island Coal Point , 43°19.8’S, 147°19.8’E ( TMAG E35239 2p); South Bruny Island , Adventure Bay , Cemetery Bluff, 43°20.388’S, 147°19.44’E ( TMAG E41956 2p); Moss Glen, 43°31.910’S, 146°53.641’E, T05-1 ( AM C.585270 p [M107],C.585271 p [M115]); Fishers Point, 43°34.260’S, 146°55.244’E, T05-4 ( AM C.585570 3p); Flensing Rock, 43°34.291’S, 146°54.856’E, T05- 2 ( AM C.585714 8p, C.585272 p [SK013]); Pancake Bay , 43°34.673’S, 146°55.293’E, T05-5 ( AM C.585273 p [M113]; Cape Portland, Petal Point, 40°46.566’S, 147°56.604’E ( TMAG E41972 3p); Herbies Landing 40°50.112’S, 147°38.724’E ( TMAG E41966 4p); Bridport—beach 40°59.808’S, 147°23.526’E ( TMAG E41957 p); S of Granite Point Bridport, 40°59.739’S, 147°23.468’E, T01-1 ( AM C.585550 22p, C.595920 p [SK552]); Tamar River , Kelso, foreshore, 41°6’S, 146°6’E ( TMAG E16716 2p); Aikenhead Point, Devonport, 41°09.997’S, 146°21.927’E, T01-2 ( AM C.585691 7p); Goat Island , foreshore of island and nearby mainland, 41°8.214’S, 146°8.196’E ( TMAG E41962 p); Somerset, foreshore, 41°2.178’S, 145°49.962’E ( TMAG E41975 14p); Somerset, 41°01.168’S, 145°47.632’E, T01-3 ( AM C.585461 14p, C.585252 p [M117]); Wynyard, Inglis River mouth, 40°58.8’S, 145°43.8’E ( TMAG E02094 2p); Boat Harbour, beach, 40°55.8’S, 145°37.2’E ( TMAG E07953 p); Rocky Cape, Castle Rock Bay , 40°53.238’S, 145°31.356’E ( TMAG E41971 6p); Rocky Cape, Picnic Beach & rocks to S, 40°52.026’S, 145°29.052’E ( TMAG E41958 p); Little Peggs Beach 40°51.084’S, 145°21.384’E ( TMAG E41970 p); Stanley, Godfreys Beach, 40°45.138’S, 145°17.67’E ( TMAG E41959 p); Marrawah, Green Point, 40°54’S, 144°54’E ( TMAG E09069 4p); Lucas Point Pilot Bay Macquarie Harbour, 42°12.241’S, 145°12.005’E, T06-1 ( AM C.585479 17p); Trial Harbour, 41°55.758’S, 145°10.434’E ( TMAG E41964 5p); King Island : E coast, 39°54.6’S, 144°6.6’E ( TMAG E04045 p); Fitzmaurice Bay , 40°3.708’S, 143°52.896’E ( TMAG E41967 p); Lavinia Beach, beach nr Lake Martha Lavinia , 39°39.018’S, 144°4.692’E ( TMAG E41973 2p). SA: Cape Northumberland , 38°03.503’S, 140°40.378’E, SA15-1 ( AM C.585452 12p); Cape Northumberland Port Macdonnell , 38°03.308’S, 140°39.398’E, SA15-2 ( AM C.585676 6p, C.595918 p [SK085]); Cape Thomas , 37°04.461’S, 139°44.659’E, SA14-1 ( AM C.585426 10+p); Fisheries Bay Lands End , 35°37.999’S, 138°06.921’E, SA13- 2 ( AM C.585464 15p); Groper Bay nr West Cape , 35°14.108’S, 136°49.883’E, SA10-1 ( AM C.585722 9p); Pondalowie Bay , 35°13.989’S, 136°49.892’E, SA10- 2 ( AM C.585712 8p, C.585215 p [SK014]); Port Neill , 34°07.102’S, 136°21.271’E, SA06-1 ( AM C.585423 20+p); Port Moonta , 34°03.273’S, 137°33.592’E, SA09- 1 ( AM C.585386 10p); Salmon Point , 33°38.547’S, 134°51.916’E, SA04-2 ( AM C.585549 22p); Wellesley Point , 33°38.483’S, 134°51.963’E, SA04-1 ( AM C.585422 10+p); Whyalla , 33°02.539’S, 137°35.511’E, SA07-1 ( AM C.585721 9p); Rocky Point , 32°12.250’S, 133°14.861’E, SA02-4 ( AM C.585421 10+p); Cape Thevenard , 32°08.703’S, 133°38.553’E, SA03-3 ( AM C.585708 8p); Ceduna , 32°07.438’S, 133°40.260’E, SA03-2 ( AM C.585451 12p); Port Le Hunte Point Sinclair , 32°05.554’S, 132°59.476’E, SA02-2 ( AM C.585447 11p); Cactus Beach Point Sinclair, 32°05.135’S, 132°58.943’E, SA02-3 ( AM C.595959 11p) .

Taxonomic remarks. The lectotype ( Fig. 17C ) is designated herein for the stabilisation of the name and to ensure the unambiguous identity of this taxon (Art. 74.1 of the Code). Our delineation of this species is based on comparative analyses of the morpho-anatomy and mitochondrial genetics of freshly collected topotypes and geographic series of additional specimens (Tables S1–2). We also demonstrate that previous treatments of S. denticulata as a synonym or variety of S. diemenensis are incorrect and that S. diemenensis and S. denticulata are distinct species. Menke (1844: 54) regarded S. diemenensis (as “ diemensis ”) as ‘closely related and associated’ with S. javanica (as “ iavana ” and “ iavanica ”), which is incorrect. The shell of S. diemenensis has more numerous and narrower ribs than that of S. javanica . Both species also differ in RS structure: AO larger, BD longer, narrower, F1 shorter in S. diemenensis than S. javanica . Both species have non-overlapping distributions in cool temperate waters of SE Australia ( Fig. 16 ) and in the Tropical Philippines ( Fig. 11 ), respectively.

Tryon & Pilsbry’s (1891: 25) reference to Patella diemensis Philippi, 1848 from Hobarttown, Tasmania, as a possible siphonariid is incorrect. This taxon is a junior synonym of Patella peronii Blainville, 1825 ( Coan & Kabat, 2017: 110). Hutton (1878: 41) stated that he earlier misidentified specimens of ‘ Benhamina obliquata ’ (= S. obliquata ) from NZ as S. diemenensis . Subsequently, Suter (1909b: 33, 1913: 599) and Hubendick (1946: 24) agreed. Hutton (1878: 10, 42) also incorrectly listed S. denticulata as a synonym of S. diemenensis and was uncertain whether S. diemenensis inhabited NZ. Herein, we establish that S. diemenensis is not present in NZ. Verco (1907: 104) incorrectly considered Trimusculus albida (Angas, 1878) as a possible white form of S. diemenensis . According to Oliver (1915: 546), Suter’s (1907) specimens of S. diemenensis were a misidentification of S. raoulensis .

Hubendick (1946: 38) treated S. denticulata Quoy & Gaimard, 1833 , S. scabra Reeve, 1856 , S. exulum Hanley, 1858 (including ‘ Ellsiphon exulorum’ Iredale, 1940) and S. raoulensis Oliver, 1915 as synonyms of S. diemenensis . Hubendick (1946: 38–39) also treated another five taxa as varieties of the former. We consider that four of these names are incorrectly assigned to S. diemenensis (i.e., denticulata Quoy & Gaimard, 1833 , scabra Reeve, 1856 , exulum Hanley, 1858 , and perplexa Oliver, 1915 ). Siphonaria exulum , S. perplexa and S. macauleyensis are all conspecific with S. e xulum. Hubendick’s (1946: 38) inclusion of S. javanica Blainville, 1827 and S. alternicosta Potiez &Michaud,1838 as possible synonyms of S. diemenensis are also rejected. McAlpine (1952: 41) erroneously treated S. scabra as a junior synonym of S. diemenensis . Yet, these are distinct species. Grove et al. (2006: 60) incorrectly listed S. denticulata , S. javanica Blainville 1827 (not Lamarck, 1819), S. exulum and S. scabra as synonyms of S. diemenensis .

External morphology ( Fig. 17O ). Foot sole smooth, reddish orange, darker at foot edge; foot wall dark yellowish grey with evenly spread white subepithelial pustules becoming more vivid and dense close to the foot sole and around pneumostomal lobe; genital pore inconspicuous, located on foot wall posterior to right cephalic fold; fringing mantle reasonably wide, thin, yellowish, translucent to transparent, extends to shell edge, outer edge lobed, weakly banded yellow and black reflecting corrugations and inner colouration of shell lip and ribs; pneumostomal lobe large and within mantle between the right ADMs, closes the pneumostomal and anal openings at the mantle edge; two small black epithelial eye spots centralised on two thick centrally touching orange grey cephalic folds that darken to their outer edge, covered with white mucous cells similar (but smaller) to those of the foot wall tissue.

Shell ( Figs 17C–G , Table S9). Small to medium sized (max sl mean = 17.7 mm, SD = 3.1 mm, n = 8), ovate; height tall; apex central, usually eroded, apical sides strongly convex, protoconch direction homostrophic (n=6; Fig. 17P ), shell whorl dextral; growth striae indistinct with weak external colour banding aligning with growth stages; rib count (mean = 29, SD = 5.6, n = 8), primary ribs off white, strongly raised, rounded and straight, extend past a fairly even shell lip to scallop the edge; very few secondary ribs, rib interstices dark, strongly prominent, paired primary ribs over an indistinct siphonal ridge; interior shell margin coloured white aligning under primary ribs, very dark brown to black aligning under rib interstices, colour extends from shell lip to spatula region, spatula yellowish brown; ADM scar indistinct, paler colour than spatula, CMS straight. Shell thickening not displayed.

Reproductive system ( Figs 20A–C; n = 2). Positioned within coelom under the respiratory cavity, over foot muscle and against right side of foot wall. GA, EG and ED positioned between BM and RAM; single GP inconspicuous, opening from an extremely small GA through foot wall posterior to right cephalic fold; AO short, wide, bluntly pointed; join of AO, GA and ED distinct, all whitish fibrous muscular tissue; ED very long, thin, bent, twisted; EG wide, lobed, with single curved, indistinct flagellum (F1); BD and CD very thin and long, jointly connect into GA between ED, AO and GP; BD noticeably longer than CD with a prominent central loop over epiphallic parts before joining BC (no distal loop), both ducts smooth, featureless, pass together outside RAM connecting into curved MG, BD ventral to CD; BC bulbous elongated, thin test, internally embedded in folds of MG (0 to 5 SPM in BC); HD long, thick, coiled, links ducts in folds of small AG to elongated narrow yellowish granulated HD; AG larger than HG, MG and AG folded, soft white tissue; SV embedded on left side of AG under BC; outer edge of AG and HG sides match curvature of inner foot wall.

Spermatophore ( Fig. 20B ). Thread-like (length = 9.35 ± 3.61 mm, n = 2), translucent, test thin; head section, tip bluntly rounded, weakly bulbous, elongate, containing a white gelatinous mass; tapers quickly into consistently filamentous transparent flagellum; both sections smooth, featureless. Head shorter and thicker than flagellum (head length = 4.7 ± 0.7 mm, n = 2; mean ~ 20% of SPM length; head width = 260 ± 42 μm; flagellum width = 45 ± 21 μm, n = 2). Typically, tightly coiled in bursa, embedded in white gelatinous mass. The SPM ( Fig. 20B ) reasonably matches the SPM of S. diemenensis figured in Hubendick (1945: 23, fig, 29) apart from width of head section.

Radula ( Figs 83A–D ). Dentition formula 35:1:35 with 141 transverse rows, n = 1, AM C.201772); single central rachidian tooth flanked squarely by 35 half row laterals, of which 3 are inner, 7 mid and 25 outer laterals (n = 1); central tooth with narrow pointed mesocone, inner lateral mesocones predominantly bicuspidate but with an irregular few unicuspidate, endo and ectocones absent ( Figs 83A–B ); mid laterals with pointed mesocone; single ectocone, protrudes at acute angle halfway along the tooth’s length; outer laterals with a broad ‘chisel’ shaped pointed mesocone flanked by small, single, pointed ecto and endocones ( Fig. 83C ), angle of separation of each cone from the mesocone varies, basal plate of outer laterals typically as broad as the tooth’s length.

Comparative remarks. Siphonaria diemenensis ( lateralis group, unit 7) represents the sister group of a clade containing the three species S. jeanae , S. propria , and S. australis ( Figs 1 , 4 ). It is well-differentiated from these species by COI distances of ≥ 18.8% ( S. jeanae ), ≥ 19.5% ( S. propria ), and ≥ 19.9% ( S. australis ) (Table S8). From other species it differs by COI distances of ≥ 20% (Table S8).

Within its range we found eight partially sympatric congeners. With four of these species, it co-occurs in Sydney, NSW, Australia: Siphonaria pravitas sp. nov. has a lower shell with stronger raised ribs and edge scalloping, no BD distal loop, larger BC, wider F1, shorter SPM. Siphonaria scabra has a paler shell with finer ribbing and coarser exterior, a longer AO, BC and F1, and a bursal loop. Siphonaria denticulata has a larger, lower shell with less prominent ribbing and a more scalloped edge, a smaller, pointed AO, shorter and wider ED, no bursal loop and a larger BC. Siphonaria emergens has a smaller, elongate, paler brown shell with a strongly offset apex, less prominent ribbing and edge scalloping.

A further five congeners are sympatric with S. diemenenesis in SE Australia: Siphonaria funiculata has a paler, taller shell with less raised ribs broadening to a fainter scalloped edge, a larger AO, shorter BD and ED, absent to smaller F1, and a larger, drop-like SPM. Siphonaria stowae has a smaller, elongate, and paler shell with a strongly offset apex, less prominent ribbing and edge scalloping, a smaller AO, shorter ED, larger BC, and shorter SPM. Siphonaria tasmanica has a lower, bluish coloured shell with a more offset apex, fainter edge scalloping and less raised ribs broadening to edge, a smaller AO and BD, shorter ED, and short, drop-like SPM. Siphonaria jeanae has a smaller, has a smaller, lower, bluish coloured shell, a smaller AO, shorter ED, and short, drop-like SPM. Siphonaria zelandica has a paler, lower shell with less prominent and finer, narrower ribbing, a shorter ED and BD, and short, drop-like SPM.

Exterior shell characteristics of S. diemenensis resemble those of S. denticulata . Hubendick’s (1946) treatment of S. scabra and S. denticulata as varieties of S. diemenensis is rejected as these are accepted herein as distinct species. A specimen figured as ‘ S. diemenensis ’ by Davey (1998: 113, text-fig.) is identified herein as S. funiculata . Our description of the radula matches that of Hutton (1883: 124, pl. 17, figs E–G), but the dentition formula is more than twice the count of 12:1:12 given by Hubendick (1946: 38). The RSs figured herein ( Figs 20A, C ) closely matches figures by other authors (e.g., Hubendick 1945: fig. 23; McAlpine, 1952: 43, fig. 2). The RS and SPM ( Fig. 20B ). Hubendick;’s (1946: 14, fig. 19) illustrations of RS and SPM of ‘ S. bifurcata ’ from ‘Port Jackson’ (= Sydney) are herein attributed to S. diemenensis with which the largely correspond apart from a narrower and shorter SPM head section. The specimen figured as ‘unit 7’ in Dayrat et al. (2014: fig. 3H) from Portland, Vic closely resembles S. diemenensis . This unit was subsequently referred to as ‘ Siphonaria sp. ( Australia)’ in González-Wevar et al. 2018. The record of ‘ S. diemanensis Quoy & Gaimard 1835 ’ (sic) in Smythe (1979: 69) from the United Arab Emirates is incorrect and well outside the known distribution of this species.

Distribution and habitat. Endemic to cooltemperate waters of south coast Australia, between just north of Sydney through to west of Cape Northumberland, South Australia, including Tasmania ( Fig. 16 ). In this study found on exposed places on intertidal rocky shores, common across upper and mid littoral, associated with mussel and barnacles, home scars common.

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 11. Occurrence records of S. sipho, S. javanica and S. japonica.

FIGURE 16. Known occurrence records of S. obliquata, S. radiata, S. diemenensis, S. australis, S. atra and S. denticulata

FIGURE 17. Shells of S. radiata, S. diemenensis, S. australis and S. capensis. A–B, U–V. S. radiata. A. Malaysia, Port Dickson, neotype AM C.585861 [M408]. B. Malacca, ZRC.MOL.24891 [SK348]. U. Port Dickson, in situ. V. Protoconch, AM C.585921 [SK337]. C–G, O–Q. S. diemenensis. C. Lectotype MNHN-IM-2000-35952. D. Tas, TS, AM C.584797 [SK047]. E. Tas, AM C.585270 [M107]. F. Vic, AM C.585286 [M168]. G. Tas, AM C.585260 [M170]. O. Animal. P. Tas, TS, in situ. Q. Protoconch, Vic, AM C.585357 [SK029]. H–J, R–T. S. australis. H. Lectotype MNHN-IM-2000-5036. I. NZ, Stewart Is, AM C.585249 [M481, SK288]. J. Stewart Is, AM C.585247 [M480, SK289]. K. Holotype of S. inculta USNM 5857. R–S. In situ and animal. T. Protoconch, AM C.265856 [SK511]. L–N. S. capensis. L. Lectotype MNHN IM 2000-38235. M. South Africa, MNHN-IM-2019- 1481 [M585]. N. IM-2019-1477 [M584]. Unlabelled scale bars = 10 mm.

FIGURE 20. Reproductive morphology of S. diemenensis and S. denticulata. A–C. S. diemenensis. A–B. NSW, Murunna Point, AM C.585001 [SK037]. C. Tas, d’Entrecasteaux Channel, TS, AM C.584797 [SK047]. D–H. S. denticulata. D, E. SPM, NSW, Kiama, AM C.585333 [SK043]. F. Qld, Currumbin Point, TS of S. currumbinensis AM C.585123 [SK033]. G–H. Qld, Yeppoon, TS of Ellsiphon marza AM C.585123 [SK030]. Scale bars = 1 mm.

FIGURE 83. Radula morphology of S. diemenensis, S. denticulata, S. restis sp. nov. and S. tasmanica. A–D. S. diemenensis, Tas, Recherche Bay, AM C.201772. A. Inner central area x256. B. central area x585. C. Outer laterals x256. D. Shell. E–H. S. denticulata, NSW, Sydney, AM C.315783 x520. E. Inner central area. F. Central area. G. Outer laterals. H. Shell. I–L. S. restis sp. nov. WA, Rottnest Is, AM C.320123. I. Inner central area x234. J. Central area x466. K. Outer laterals x466. L. Shell. M–P. S. tasmanica, Tas, Eaglehawk Neck, AM C.311615. M. Inner central area x505. N. Central area x505. O. Outer laterals x650. P. Shell. Unlabelled scale bars 1 mm.