Siphonaria campestra, B. W. Jenkins & Köhler, 2024

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 : 141-142

Siphonaria campestra sp. nov.

( Figs 53C–D , 54A–C, M–N )

Material examined. Type material. Holotype, from Dolokoan Beach 8°31.424’S, 125°37.091’E, N of Dili, Timor-Leste; coll. B.W. Jenkins, TL01-1, 14 July 2019 ( AM C.584823 [M447, SK230 (RS)], Fig. 54A ). Three paratypes, same data as holotype ( AM C.585353 p [SK265], AM C.585354 p [SK266], Fig. 54B ; AM C.585355 p [SK267], Fig. 54C ).

External morphology ( Fig. 54N ). Foot sole evenly grey; foot edge and cephalic folds cream, slightly lobed; foot wall, mantle and pneumostomal lobe evenly shaded dark grey, lighter to foot edge; mantle narrower than foot wall, translucent, elongated at anterior, edge thickened, lobed with grey/black banding (over mantle width) aligning with rib interstices and interstice width; pneumostome elongated.

Shell ( Figs 54A–C ; Table S9). Small sized (max sl mean = 8.1 mm, SD = 0.6 mm, n = 4), ovate; height low to medium; apex offset to posterior and slightly left; apical sides convex, concave and elongated to posterior; protoconch direction homostrophic (n = 1), shell whorl dextral; growth striae prominent uneven, shell thickness thin; shell edge uneven; rib count (mean = 28.3, SD = 2.3, n = 4), exterior with dual shaded bands, paler apical (white ribs and pale brown interstices) and darker shell edge (white ribs and black/dark brown interstices); primary ribs white, crooked, broaden to shell lip, weakly protrude beyond shell lip to unevenly scallop and corrugate the edge, 0–1 interspersed pale white finer secondary ribs; loosely paired primary ribs form siphonal ridge, no more prominent than other primary ribs; interior shell margin very dark brown to black, white rays on shell margin to lip align under primary/secondary ribs, siphonal groove indistinct, spatula very dark chocolate to black with some underlying white; ADM scar distinct, CMS straight; thickening of shell lip not apparent.

Reproductive system ( Fig. 53C; n = 2). Positioned within entire right side of coelom, against foot wall on foot muscle, under the respiratory cavity occupying large proportion of animal body volume; epiphallic parts positioned over BM. GA small, with singular GP through foot wall; AO very small, narrow, bluntly pointed, joined to lower ED and upper GA; ED very short, very broad, centrally bent, joins to side of GA; GA, AO, ED all white muscular fibrous tissue; EG very large, soft whitish tissue, slightly folded, joins ED; extension joins in parallel to single very broad flagellum (F1), similar width to ED, appears as an extension of ED; BD and CD connect side-by-side into GA between ED join and GP, both ducts short, slightly bent, smooth, thickened, whitish, featureless, pass closely together inside outer RAM ( BD over CD) into soft white folded tissues of MG; MG / AG complex medium; CD connecting to ducts, BC embedded in folds close to embedded purplish SV; BD without distal loop and MA, with loop immediately prior to BC; BC relatively large, spherical, thin whitish translucent test; HD short, narrow, coiled, links ducts in soft white folded tissues of AG to yellowish granulated HG; outer edge of MG lobbed; AG larger than HG, outer sides match curvature of inner foot wall.

Spermatophore ( Fig. 53D ). Broad head with short flagellum (length = 2.38 mm, n = 1); head section cylindrical, bulbous, centrally twisted, rounded tip; test thin, smooth, featureless, translucent encasing a white opaque central core; short tapering section merges head to filamentous flagellum; head shorter, wider than translucent flagellum (head length = 0.95 mm, ~ 40% of SPM length, head width = 103 μm; flagellum width = 17 μm, n = 1); 1 SPM found coiled in two BCs ( Fig. 53D ).

Comparative remarks. Siphonaria campestra sp. nov. ( normalis group, unit 82) is most closely related to S. normalis , S. madangensis , S. fuliginata , and S. costellata , with which it forms a sub-clade in the normalis group ( Figs 1 , 4 ). However, it is well-differentiated from other species by COI distances of ≥ 18% (Table S2). This species has been found in sympatry with five congeners in TL: For comparisons with S. alba , S. javanica , and S. viridis refer to comparative remarks under these species. Siphonaria forticosta sp. nov. has a larger, darker shell with a more distinct siphonal ridge, a larger BC and narrower ED. Siphonaria planucosta sp. nov. has a larger shell with more raised ribbing, a less prominent siphonal ridge, a narrower AO, BD with distal loop, and a larger BC.

Distribution and habitat. Recorded from Dolokoan Beach, Timor-Leste ( Fig. 51 ). In this study, found in sheltered positions (mainly crevices) on moderately exposed rocky shores, upper and lower littoral levels ( Fig. 54M ).

Etymology. From ‘campestris’ (Latin = level, even), referring to the level or even primary ribs on the shell.

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 51. Known occurrence records of S. alba, S. asghar, S. propria, S. jeanae, S. emergens, S. oblia and S. campestra sp. nov.

FIGURE 53. Reproductive morphology of S. jeanae, S. campestra sp. nov., S. camura sp. nov., S. caubianensis sp. nov and S. christmasensis sp. nov. A–B. S. jeanae, WA, Rottnest Is, AM C.585820 [SK215]. C–D. Holotype of S. campestra sp. nov., Timor- Leste, Dili, AM C.584823 [M447, SK230]. E–F. Holotype of S. camura sp. nov., Okinawa, Tancha Bay, AM C.585614 [M491, SK310]. G–H. S. caubianensis sp. nov., Philippines, Polillo Is, WAM S113803 [M600, SK557]. I. Holotype of S. christmasensis sp. nov., CI, Flying Fish Cove, AM C.595957 [M298]. J. CI, AM C.585321 [SK083]. Scale bars = 1 mm.

FIGURE 54. Shells of S. campestra sp. nov., S. caubianensis sp. nov., S. christmasensis sp. nov. and S. costellata sp. nov. A–C, M–N. S. campestra sp. nov., Timor-Leste, Dili. A. Holotype AM C.584823 [M447, SK230]. B. Paratype AM C.585354 [SK266]. C. Paratype AM C.585355 [SK267]. M. In situ. N. Animal. D–E, O–P. S. camura sp. nov., Okinawa, Tancha Bay. D. Holotype AM C.585614 [M491, SK310]. E. Paratype AM C.584920 [M490, SK309]. O. In situ. P. Protoconch, AM C.585613 [SK510]. F–G. S. caubianensis sp. nov., F. Philippines, Caubian Is., holotype AM C.595933 [SK560]. G. Philippines, NW Polillo Is, WAM S113803 [M600, SK557]. H–J, Q–R. S. christmasensis sp. nov., CI, Flying Fish Cove. H. Holotype AM C.595957 [M298]. I. Paratype WAM S74040 [SK069]. J. Paratype, Ethel Bch AM C.584846 [M308]. Q. Protoconch AM C.585319 [SK071], R. CI, in situ. K–L, S–T. S. costellata sp. nov. K. Singapore, Lazarus Island, Holotype AM C.585236 [M416, SK100]. L. Paratype AM C.585226 [M338]. S. Protoconch, AM C.585233 [SK099]. T. In situ. Unlabelled scale bars 10 mm.