Siphonaria stowae Verco, 1906

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 : 121-123

Siphonaria stowae Verco, 1906

( Figs 46A–C, M–O , 47A–B )

Siphonaria stowae Verco 1906: 223–224 , pl. 8, figs 3–8 (type locality: Pandolowie [incorrect spelling of Pondalowie] Bay, Spencers Gulf; SA).— Gatliff 1907: 35; Verco 1907: 105; 1912: 205; Hedley 1915: 752; Hubendick 1945: 70; Cotton 1959: 411; Galindo 1977: 416; White & Dayrat 2012: 68.

Kerguelenia stowae — Hedley,1916b: 215; 1917b: M96; May 1921: 89; Gatliff & Gabriel 1922: 156; May 1922: 156; 1923: 87, pl. 41, fig. 5.

Pugillaria stowae — Iredale 1924: 276; Cotton & Godfrey 1932: 155, pl. 3, fig. 5; Macpherson & Chapple 1951: 142; Cotton 1959: 411; Macpherson & Gabriel 1962: 264; Macpherson 1966: 256; Grove et al. 2006: 60; Jenkins 2018: 276, figs 2A–V, 3A, B, 4A–D.

Pugillaria stowae comita Iredale 1924: 183 (type locality: Twofold Bay, NSW).— Iredale & McMichael 1962: 82; White & Dayrat 2012: 61; Jenkins 2018: 276, figs 2J–O.

Siphonaria (Pugillaria) stowae — Thiele 1931: 472; Morrison 1963: 7.

Siphonaria (Kerguelenia) stowae — Hubendick 1945: 59, 63, 70.

Siphonaria (Liriola) stowae — Hubendick 1946: 26, 28, 29.

Kerguelenella stewartiana — Hubendick 1946: 28 (not K. stewartiana Powell, 1946 ).

Kerguelenella stowae — Burn & Bell 1976: 234.

Siphonaria (Kerguelenella) stowae — Christiaens 1980a: 80.

Pugillaria comita — Grove et al. 2006: 60.

Material examined. Type material. Lectotype of Siphonaria stowae ( SAM D.33484 ; figured in Verco 1906: figs 3–5; Jenkins, 2018: fig. 2A–C). Eight paralectotypes of Siphonaria stowae from Pandolowie [sic Pondalowie] Bay , Spencers Gulf], SA ( SAM D.13590 , lot labelled as ‘holotype’, largest figured in Jenkins 2018: fig. 2D–F).

Three syntypes of Pugillaria stowae comita from Twofold Bay , NSW, [ Australia] coll. R. Bell [undated], T. Iredale coll. ( AM C.265927 , two figured in Jenkins 2018: fig. 2J–O) .

Other, non-type material. Australia, NSW: Woody Head , near Iluka , 29°22.0′S, 153°22.50′E ( AM C.116737 6d); Clarence River , 29°25.50′S, 153°21.00′E ( AM C.398326 2d), 29°25′S, 153°21′E ( AM C.265949 2d); Woolgoolga, 30°06.70′S, 153°12.300′E ( AM C.398328 d); Port Stephens , between beacons, 32°42.397′S, 152°11.502′E ( AM C.265967 d); North Fingal Bay , 32°44.750′S, 152°10.500′E ( AM C.398325 6d); Fingal Bay , 32°45.0′S, 152°10.500′E ( AM C.398324 d); Patonga, BrokenBay, 33°33.111′S, 151°16.570′E ( AMC.2659614d); Collaroy Beach, N of Sydney, 33°44.0′S, 151°18.0′E ( AM C.398336 d), 33°43.700′S, 151°18.0′E ( AM C.398335 d); Manly Beach, 33°47.817′S, 151°17.368′E ( AM C.265964 d); Ocean Beach, Manly, 33°47.853′S, 151°17.398′E ( AM C.265970 3d); Middle Harbour, between Grotto and Dobroyd Points, 33°48.897′S, 151°16.085′E ( AM C.265966 d); Balmoral Beach, 33°49.700′S, 151°15.030′E ( AM C.030179 2d); Off Chinamans Beach, 33°48.870′S, 151°14.965′E ( AM C.265976 2d); Sydney Harbour, Quarantine Bay , 33°50.863′S, 151°14.438′E ( AM C.265973 d); Bradleys Head, 33°51.300′S, 151°14.700′E ( AM C.398327 2d); Sydney , Little Coogee Bay , 33°55.300′S, 151°15.600′E ( AM C.398322 d); Botany Bay , Kurnell, 34°0.580′S, 151°12.380′E ( AM C.398332 2d); Port Hacking , S of Sydney , Cronulla , Gunnamatta Bay , 34°3.950′S, 151°8.550′E ( AM C.398330 d); SW end Gunnamatta Bay , 34°4.300′S, 151°8.700′E ( AM C.398334 d); Sussex Haven and Wreck Bay , 35°10.203′S, 150°41.293′E ( AM C.22532 d; AM C.265932 d); Off Montague Island , Narooma, 36°14.347′S, 150°13.015′E ( AM C.265974 4d); Twofold Bay , Murrumbulga Point, 37°04.702′S, 149°53.103′E ( AM C.150582 p). Vic: 1.6 km N of Gabo Island, 37°34.0′S, 149°56.0′E ( AM C.398323, 1 d); Mallacoota, 37°34.0′S, 149°46.600′E ( AM C.50394 2d); Bear Gully, Waratah Bay , 38°20′S, 146°00′E ( MV F169206 1p); Inverloch, 38°38′S, 145°43′E ( MV F161257 2p); San Remo, Western Port , 38°32.0′S, 145°23.0′E, V07- 1 ( AM C.030683 2d, C.585616 p [SK393]), 38°31.489’S, 145°21.858’E ( AM C.585583 3p); Flinders, Western Port Bay , 38°29.0′S, 145°1.0′E ( AM C.398366 d, AM C.265936 d); ‘ Clondrisse’ E of Cape Schanck, 38°29.583′S, 144°53.654′E ( MV F193073 p); Port Phillip Bay , 38°09′S, 144°46′E ( MV F185072 2p); Cheviot Beach, Point Nepean, 38°18′S, 144°40′E (F.87801 p); Andersons Point, Portland, 38°19.967′S, 141°36.604′E ( MV F126944 p). Tas: King Island : Gulchway, S of Surprise Bay, 40°08.023′S, 143°54.205′E ( MV F193075 p); Fraser Beach, Sea Elephant Bay , 39°54.410′S, 144°06.584′E ( AM C.265930 d); West Head , Greens Beach, Tamar River mouth, 41°5.0′S, 146°45.0′E ( AM C.398367, 1 d); Park Beach Dodges Ferry 42°51.716’S, 147°36.665’E ( AM C.585469 11p, C.584835 p [M109, SK018], C.584914 p [SK216], C.585264 p [SK007], C.585265 p [M110]). SA: Guichen Bay , near Cape Dombey, 37°7.233′S, 139°45.967′E ( SAM D.33486 3d); Stokes Bay , N coast of Kangaroo Island , 35°37′S, 137°12′E ( AM C.265968 2d); Normanville, S of Adelaide, 35°26.800′S, 138°18.500′E ( AM C.398369 d); Adelaide , Glenelg Beach, S of Adelaide, 34°58.0′S, 138°32.0′E ( AM C.265963 d, AM C.398370 d); Henley, 34°55.430′S, 138°29.595′E ( AM C.265962 2d); Grange, 34°58.215′S, 138°30.471′E ( SAM D.33490 4d); Spencer Gulf, Eyre Peninsula, Tumby Bay , 34°22.0′S, 136°8.0′E ( AM C.398372,1 d); Arno Bay , 33°56.0′S, 136°35.0′E ( AM C.398368 10+d); Pondalowie Bay , 35°13.989’S, 136°49.892’E ( AM C.585492 p); Near Salmon Point, Elliston Bay , 33°39.0′S, 134°53.0′E ( AM C.265905 1d); Sceale (sic Sceales) Bay, Cape Blanche, 33°00.237′S, 134°11.502′E ( SAM D.33485 11d); Franklin Islands , Investigator Group, 32°26.450′S, 133°39.735′E ( SAM D.33489 3d); Point Sinclair, 32°6.0′S, 132°59.0′E ( AM C.398371 d). WA: Gnarabup Beach, S of Margaret River, 34°1.0′S, 114°59.0′E ( AM C.398365 d); Kilcarnup, N side Margaret River , 33°57.0′S, 114°59.0′E ( AM C.398360 3d); Ellensbrook (S Cowaramup), near Margaret River mouth, 33°53.0′S, 114°59.0′E ( AM C.398361 d, AM C.265965 9d, AM C.398363 d, AM C.398364 9d); N side Cape Naturaliste Lighthouse, 33°32.752′S, 115°0.418′E ( AM C.265975 d); Bunbury, 33°18.750′S, 115°39.061′E ( SAM D.33488 2d); Point Peron, 48 km S of Perth, 32°16.0′S, 115°41.0′E ( AM C.398358 d, AM C.398357 3d); Garden Island, S of Perth, 32°14.0′S, 115°41.0′E ( AM C.398359 11d); Cockburn Sound, Jervoise Groyne, 1.6 km S of Woodmans Point, 32°9.0′S, 115°46.0′E ( AM C.398362 d); Rottnest Island, 32°00.683′S, 115°30.993′E ( SAM D.33492 7d); Geraldton, 28°46.143′S, 114°36.283′E ( SAM D.33491 d) .

Taxonomic remarks. The lectotype has been designated by Jenkins (2018: 3). Examinations of freshy collected topotypic specimens herein ( Fig 46A–C ) validate the identity of S. stowae and confirm that S. stowae comita is its junior synonym. Hedley (1916a: 220) transferred S. stowae to the genus Kerguelenia . Refer to Jenkins (2018: 276) for comments on type specimens, including labels. The present description is based on the re-description of this species in Jenkins (2018: 276) and is expanded upon for completeness and taxonomic consistency.

External morphology ( Fig. 46O ). Foot wall, mantle, pneumostomal lobe and cephalic folds pale grey to cream, foot sole darker grey paling to foot edge; mantle narrow, thin, translucent with thickened unlobed fringe, even pigmented shading only at foot wall mantle join; pneumostomal lobe on right side within mantle, covering inconspicuous anus in foot wall; two black ‘Eye’ spots prominent centrally on touching cephalic folds; genital pore inconspicuous, positioned in foot wall posterior to right cephalic fold.

Shell ( Figs 46A–C, M ; Table S9). Small sized (max sl <10 mm), ovate, cap-like, arched dorsally, height medium to tall; apex lower than shell height, dorsally aligned close to or over posterior edge ( Jenkins 2018: fig. 2), laterally offset 10–15 ° to left of transverse centre line (cl); exterior white to cream with irregular red-brown apical striations and blotches, coloration and patterning variable; Shell whorl dextral, protoconch direction homostrophic (n=1; Jenkins 2018: fig. 2V); posterior margin weakly concave, other margins convex ( Jenkins 2018: fig. 2); in larger specimens (sl> 8 mm), lip thickened, opaque, ribs prominent, irregularly spaced, flattened, weakly corrugated, often distorted by prominent growth striae ( Jenkins 2018: fig. 2F, M); rib interstices are irregular and red-brownish denoted by coloured apically aligned bands or streaks ( Jenkins 2018: fig. 2A–C); growth striae prominent and uneven; in small specimens, shell translucent, exterior smooth and polished, ribs indistinct, lip thin, unscalloped and translucent to edge, red-brown exterior of irregular rib interstices shows through to interior between ADM scar and lip ( Jenkins 2018: fig. 2H, Q); interior smooth, cream coloured, spatula smooth and white; ADM scar indistinct, weakly indented, posterior of scar shaded red-brown ( Jenkins 2018: fig. 2), cephalic ADM scar (cam) indistinct, straight to slightly convex; siphonal groove weakly indented.

Reproductivesystem ( Fig.47A;n =3).Predominantly located in posterior of coelom; HG granulated, HD and folds of AG situated to posterior under digestive gland and pallial cavity; a small rounded brownish BC and BD located behind pneumostomal opening and beside posterior RAM; BD narrow elongate; HG connected by several short thin translucent ducts; MG and AG with translucent folds; SV positioned to side of these folds; EG, ED and small bulbous GA are situated to right side of BM just behind RAM; two short thick flagellum present at join of ED and EG; outer layer of GA translucent whitish with white opaque central layer; BD passes through the RAM; a thickened coiled CD decreasing in diameter opens into GA; a single (monoaulic) small GP opens from GA through foot wall posterior to right cephalic fold and in front of right anterior RAM; BD and CD open separately into GA close to GP.

Spermatophore ( Fig. 47B ). Thread-like (length = 3.63 ± 1.06mm, n = 2), translucent, test thin; head section, tip bluntly rounded, evenly cylindrical, elongate, containing a white gelatinous mass; taper region into the filamentous transparent flagellum is short; both sections smooth, featureless. Head shorter and thicker than flagellum (head length = 1.46 ± 0.11 mm, ~ 41% of SMP length, head width = 120 ± 20 μm; flagellum width = 13 ± 15 μm). We found 7 SPM tightly coiled each in two bursas.

Radula ( Jenkins 2018: fig. 4A–D). each transverse row has a single narrow central rachidian tooth flanked squarely by mirrored half rows of block-like lateral teeth (fig. 4A); tooth size in a single row decreases rapidly from the more solid (around 4× larger) innermost laterals to smaller outermost mid laterals, the gap between rows notably increases (fig. 4B, D); each half row has on average eight mid and eight outer lateral teeth; inner teeth interlock via forks and notches, centrals anterior dualpronged fork, blunt posterior notch; laterals possess a single outward pointing basal prong and notch (fig. 4B); central tooth significantly lower and smaller than adjacent lateral teeth with single weakly-pointed mesocone, basal plate of similar length, narrower than adjacent laterals (fig. 4A); inner laterals (i.e., without ecto/endocones) uncommon, irregular (fig. 4A); mid lateral mesocones around half length of base, edge shallow ‘U’ shaped, bluntly bi-cuspidate (some weakly tricuspidate), tips of inner lateral mesocones often erode back of tooth in front; single ectocone increasing from almost no ectocone to very prominent ectocone almost width and half height of mesocone (figure 4B); outer lateral (fig. 4B) mesocone single cusped, ecto/endocones variably-shaped bluntlypointed tooth bases progressively widen to outer ribbon edge; outside outer laterals (from tooth 13) possess additional endocone, ecto/endocones appear as separate cones, some almost as large as mesocones size, without an angle of separation from mesocone. Radula dentition agrees with original description ( Verco 1906: 224) apart from having four fewer laterals per half row than Verco’s formulae (‘around 22’); and for the lack of evidence that the central tooth ‘tends to be bilobed’ (i.e., bi-cuspidate). Dentition formula 16:1:16 +/− 2 (n = 3; row count not assessed), 22:1:22 ( Hubendick 1946: 29).

Comparative remarks. Siphonaria stowae ( atra group, unit 52) is member of a subclade of Clade H containing the species S. zelandica (unit 26), S. acmaeoides (unit 91), and S. restis (unit 54) ( Figs 1 , 2 ). It differs from these species by COI distances of ≥ 17.5% (Table S4). Throughout the range of S. stowae we found ten congeners with partly sympatric distributions. Four species are sympatric in south-eastern Australia. Siphonaria emergens has a smaller, mottled orange/ brown shell with less edge scalloping, S. pravitas sp. nov. has a larger, lower shell with stronger ribbing and edge scalloping, a more prominent siphonal ridge, a larger AO and BC, and a longer ED. Siphonaria scabra has a larger, taller shell with greater edge scalloping, a larger AO, longer ED, and a longer SPM. For comparison with S. denticulata refer to comparative remarks under that species. Five species have been found in sympatry in southern Australia: For comparisons with S. diemenensis , S. funiculata , S. jeanae , S. tasmanica , and S. zelandica refer to comparative remarks under these species. One species occurs in sympatry in south-western Australia: Siphonaria restis sp. nov. has a larger, lower shell with stronger raised ribbing and greater edge scalloping, a larger, bulbous, blunt AO, and a longer BC. The combined shell geometry, size and colouration of S. stowae is very distinctive and unlike any other siphonariid.

Distribution and habitat. Southern coasts of Australia, from Iluka, northern NSW, through Vic, Tas, SA to Geraldton, WA ( Fig. 48 ). Found in sheltered rocky intertidal platforms and rocky areas, often on rocks in tidal pools and associated with white Lithothamnion algae, at mid littoral level ( Fig. 46N ).

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 2. Maximum Likelihood phylogram (partial, species not collapsed). Clades G–I (atra group) 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 (seeTables 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 spread over two pages.

FIGURE 46. Shells of S. stowae, S. opposita, S. madagascariensis and S. lentula. A–C, M–O. S. stowae. A–B. Tas, Dodges Ferry. A. AM C.585265 [M110]. B. AM C.584835 [M109]. C. Vic, San Remo, AM C.585616 [SK393]. M. WA, Gnarabup Beach, AM C.398365, protoconch. N. Vic, in situ. O. Vic, animal. D–F, R–T. S. opposita. D. Lectotype of Mallorisiphon oppositus AM C.103714. E. Qld, Yeppoon, TS, AM C.585135 [M424]. F. Qld, Gladstone, AM C.585866 [M213]. P. Qld, Scarborough, AM C.585819 [M458, SK181]. R. Qld, animal. S. Qld, in situ. T. Protoconch, AM C.585126 [SK136]. G–I. S. madagascariensis, Madagascar, Itampolo. G. AM C.584818 [M267]. H. AM C.584959 [M272]. I. AM C.584957 [M270]. J–L, Q. S. lentula. J. Lectotype of Mestosiphon lentulus AM C.103712. K. LHI, TS, AM C.608189 [SK051]. L, Q. Protoconch, LHI, TS, AM C.546718 [SK053]. Unlabelled scale bars = 10 mm.

FIGURE 47. Reproductive morphology of S. stowae, S. opposita, S. madagascariensis and S. lentula. A–B. S. stowae, Tas, Dodges Ferry. A. AM C.584914 [SK216]. B. AM C.585264 [SK007]. C–G. S. opposita. C–D. Qld, Scarborough, AM C.585819 [M458, SK181]. E. Qld, Yeppoon, TS. AM C.585135 [M424, SK237]. F–G. Qld, Scarborough, AM C.585863 [M431, SK135]. H–I. S. madagascariensis, Madagascar, Itampolo, AM C.584818 [M267]. J–K. S. lentula, LHI, TS, AM C.608189 [SK051]. Scale bars = 1 mm.

FIGURE 48. Known occurrence records of S. stowae, S. madagascariensis, S. lentula, S. opposita and S. monticulus