Siphonaria nuttallii Hanley, 1858

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 : 104-107

Siphonaria nuttallii Hanley, 1858

( Figs 39I–J , 40K–N, S, U–V )

Siphonaria nuttallii Hanley 1858b: 153 (type locality: ‘littora insularum sandvicensium’ [coast of the Hawaiian Islands]).— Paetel 1875: 92; Coan & Kabat 2012: 336; White & Dayrat 2012: 66; Dayrat et al. 2014: 266.

Siphonaria nuttalli — Paetel 1873: 117; 1883: 178; 1889: 429; Pilsbry 1920b: 379; Christiaens 1980a: 79 (incorrect subsequent spelling of nuttallii ).

Siphonaria normalis forma chirura Pilsbry 1920b: 380 , fig. 15 (type locality: Hawaii).— Edmondson 1946: 188, fig. 102b.

Siphonaria (Siphonaria) nuttalli — Hubendick 1945: 73; 1946: 17, 50, 51–52, 63, pl. 4, fig. 1–4 (incorrect subsequent spelling of nuttallii ).

Siphonaria chirura — Baker 1964: 159; White & Dayrat 2012: 61.

Siphonaria normalis — Kay 1979: 493, figs 157I–J.

Material examined. Type material. Lectotype of Siphonaria nuttallii Hanley, 1858b , present designation, from Hawaii ( NHMUK 20120166/1 , Fig. 40K ). Four paralectotypes, same data as lectotype ( NHMUK 20120166/2-5 , Fig. 40N ).

Three syntypes of Siphonaria normalis forma chirura Pilsbry, 1921 from Kahoolawe , Hawaii [ USA]; coll. H. A. Pilsbry, 1913 ( ANSP 281800a ; ‘lectotype’, refer Taxonomic remarks).

Other, non-type material. Hawaii; Maui: Ho’okipa Beach , 20°56.029’N, 156°21.411’W HA03-4 ( AM C.585444 11p, C.585661 3p form chirura , C.584894 p [M470, protoconch G7], C.584895 p [M471, SK273, form chirura ], C.584896 p [M472, SK079], C.584897 p [M486, SK305, form chirura ], C.584898 p [SK211]).

Taxonomic remarks. The largest syntype of S. nuttallii is herein designated as the lectotype ( Fig. 40K ) for the stabilisation of the name (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 ( Fig. 40L ) and S. normalis var. chirura ( Fig. 40M ) and geographic series of additional specimens (Table S1). We establish S. normalis var. chirura as a new junior synonym. The designation of lectotype for S. chirura by Baker (1964: 159 ‘ANSP TSD now: 281800a’) is invalid as it is not based on a syntype (Art. 74.1 of the Code). The specimen is badly worn. Pilsbry (1920b: 379) and Cernohorsky (1972: 210) erroneously treated S. nuttallii as a synonym of S. normalis .

External morphology. Foot sole, foot wall, mantle, cephalic folds, pneumostomal lobe evenly grey/green, paler to foot edge; irregular black blotches of pigmentation on foot wall and concentrated over centre cephalic folds; mantle thin, translucent narrower than foot wall, covers exposed inner shell lip, wider at anterior, mantle edge thickened, dark edge band, weakly lobed with even black pigmentation rays aligned with underside of shell rib interstices; genital pore indistinct; small black epithelial eye spot centralised on each of centrally touching cephalic folds; pneumostomal lobe long broad under mantle between the right anterior and right posterior ADMs.

Shell ( Figs 40K–N, S ; Table S9). Small sized (max sl mean = 12.7 mm, SD = 1.9 mm, n = 9), circular ovate; height medium; apex offset weakly posterior and laterally central, apical sides convex to straight; protoconch direction homostrophic to central (n = 3; Fig. 40S ), shell whorl dextral; growth striae prominent in bands, shell thickness thick; rib count (mean = 42, SD = 2, n = 9); exterior uneven with faint radial banding; primary ribs pale tan, fairly straight to wavy, broaden and weakly raised to shell edge, ridges and ends rounded, protrude beyond shell edge; edge finely scalloped and unevenly corrugated; 2–5 finer secondary ribs between primary ribs, rib interstices darker brown with white patches; siphonal ridge formed by paired primary ribs; Interior shell margin white rays under primary ribs, dark brown rays under rib interstices, rays extend from shell lip over shell margin fading to spatula; siphonal groove indistinct, paler than shell margin; spatula mottled dark brown to white; ADM scar distinct, dark brown, CMS convex; no thickening or whitening of shell lip observed.

Reproductive system ( Fig. 39I; n = 4). 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 between BM and RAM; GP small, singular, positioned through foot wall behind right cephalic fold, GA small, prominent; AO large, elongate, broad, bluntly pointed, slightly bent centrally, joins to top of GA in conjunction with relatively short, strongly twisted, very broad ED; EG large white folded, single long narrow looped flagellum F1 appears as an extension of ED at join with EG; AO, GA and ED all muscular white tissue; BD and CD connect closely in opposite directions into GA between connections of ED and AO, both ducts narrow smooth featureless, pass together through RAM connecting into MG, BD above and longer than CD, with distal loop and MA to inner foot wall; BC medium in size, spherical, embedded in folds of MG, test translucent; SV embedded in AG; HD reasonably long, thick coils, brown markings, links AG to smaller yellowish granular HG; MG and AG folded soft white tissue; sides match curvature of inner foot wall on right posterior of coelom; outer edge of MG lobed.

Spermatophore ( Fig. 39J ). Body cylindrical, thread-like (length = 6.7 mm, n = 1), test thin, translucent; head tip tapered bluntly rounded, section containing a white gelatinous core, tapers to a thin flagellum and tip; both sections smooth, featureless; head longer, thicker than flagellum (head length = 5.1 mm; 76% of SPM length; flagellum length = 1.6 mm; head width = 95 μm; flagellum width = 16 μm), 2 SPM tightly coiled in white gelatinous mass in one BC [M471].

Comparative remarks. Siphonaria nuttallii ( plicata group, unit 85; Figs 1 , 2 ) differs from other species by COI distances of ≥ 20% (Table S7). Siphonaria nuttallii occurs in sympatry with S. normalis at Big Island, Hawaii; refer to comparative remarks under that species. Siphonaria nuttallii has a similar shell morphology like other members of the plicata group, such as S. mauiensis sp. nov. (also occurring on Maui, but not found in immediate sympatry), S. plicata , S. tongatapuensis sp. nov. (both from Tonga), S. monticulus (from Lifou), S. namukaensis sp. nov. ( Fiji and NC) and S. poindimiensis sp. nov. However, all these species are genetically well-differentiated. Specimens figured by Hubendick (1946: 91, pl. 4, figs 1–4) as S. nuttallii and S. chirura by Edmondson (1946: 188, figs 102b) are consistent with typical characteristics of S. nuttallii as defined herein and are within the known distribution of this species. Specimens figured as ‘ S. normalis’ in Kay (1979: 493, figs 157I, J) from Hawaii are likely of S. nuttallii for closely resembling the types ( Figs 40K–N ).

Distribution and habitat. Only known from Maui, Hawaii ( Fig. 37 ), found on moderately exposed rocky shores in sheltered positions, mid littoral level ( Fig. 40U ).

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 37. Known occurrence records of S. bifurcata, S. fuliginata, S. lirata, S. exulum, S. belcheri, S. nuttallii, S. incerta and S. tasmanica

FIGURE 39. Reproductive morphology of S. carbo, S. belcheri, S. exulum and S. nuttallii. A–B. S. carbo, Mozambique, MNHN IM 2019-16165 [M587]. C–D. S. belcheri, Pakistan, Karachi. C. AM C.585500 [SK146]. D. AM C.595930 [SK533]. E–H. S. exulum. E. NI, TS, AM C.585025 [SK041]. F. LHI, AM C.546717 [SK052]. G–H. Kermadec Is, Raoul Is, TS of S. raoulensis. G. AM C.475847 [M513]. H. AM C.475848 [M512]. I–J. S. nuttallii, Hawaii, Maui, TS. I. AM C.584898 [SK211]. J. AM C.584895 [M471, SK273]. Unlabelled scale bars = 1 mm.

FIGURE 40. Shells of S. belcheri, S. nuttallii and S. thersites. A–J, R. S. belcheri. A. Lectotype NHMUK 1900.3.19.29. B–G. Paralectotypes NHMUK 1900.3.19.30-34. G. NHMUK 1900.3.19.28. H. Pakistan, Karachi, AM C.585102 [M227]. I. Karachi, AM C.585500 [SK146]. J. Karachi, AM C.585101 [M238]. R. Karachi, in situ. K–N, S, U–V. S. nuttallii. K. Lectotype NHMUK 20120166/1. L. Hawaii, Maui, TS, AM C.584898 [SK211]. M. TS of S. chirura AM C.584895 [M471, SK273]. N. Paralectotypes NHMUK 20120166. S. Protoconch, AM C.584894 [M470]. U. Maui, in situ. O–Q, T. S. thersites, O. Holotype USNM 11852. P–Q. Alaska, Cook Inlet. P. CBG 11BIOAK-0592 [SK553]. Q. 11BIOAK-0589 [SK554]. T. Washington, Neeah Bay, TS, in situ. Unlabelled scale bars = 10 mm.