Lyonsiella tentaculata, Pacheco & Teso & Pastorino, 2024

Pacheco, Leonel I., Teso, Valeria & Pastorino, Guido, 2024, Use of traditional tools and micro-computed tomography for the taxonomy of carnivorous bivalves from the deep waters of Southwestern Atlantic, Zoological Journal of the Linnean Society 202, pp. 1-23 : 16-18

publication ID

https://doi.org/ 10.1093/zoolinnean/zlae118

publication LSID

lsid:zoobank.org:pub:1C0D753-0F6F-4D0C-BD1D-8D1C6D588F30

persistent identifier

https://treatment.plazi.org/id/03857E58-A10F-FF99-FC63-FAEDFED8FE9A

treatment provided by

Plazi

scientific name

Lyonsiella tentaculata
status

sp. nov.

Lyonsiella tentaculata sp. nov.

( Figs 11A, B, D, F, G View Figure 11 , 12 View Figure 12 )

urn:lsid:zoobank.org:act:1443D27C-D033-4721-B12CE1B7BA98F3E8

Type material: Holotype: MACN-In 44327, one individual. Paratypes: MACN-In 44326, two valves.

Type locality: Mar del Plata submarine Canyon (38°01 ʹ 26″S, 53° 51 ʹ 01″W), 2212 m GoogleMaps .

Etymology: Ŋe name tentaculata , from the Latin tentaculum, refers to the numerous siphonal tentacles in comparison to other species of the genus.

Distribution

New records: Mar del Plata Submarine Canyon (1395–2212 m) and Burdwood Bank (647 m).

Bathymetry: 647–2212 m.

Material examined: MACN-In 44328 (37°49 ʹ 40″S, 54°07 ʹ 56″W, 1395 m) one individual; MACN-In 44326 (54°36 ʹ 14″S, 62°50 ʹ 55″W, 647 m) two valves (paratypes).

Diagnosis

Shell ≤ 14 mm long, ornamented by ≤50 radial lines spaced by radially oriented groups of pyramidal spines. Siphons surrounded by 25 siphonal tentacles, 12 associated with inhalant siphon and 13 with exhalant.

Description

Shell medium in size (≤ 14 mm L, 11 mm H, 4.6 mm W), fragile, somewhat translucid, oval-trapezoidal, inequilateral. Inequivalve; left valve more rectangular, right valve slightly larger and with dorsal and ventral margins projecting beyond the left valve. Surface covered by ≤50 radial lines spaced by radially oriented groups of four to eight pyramidal spines, usually covered by debris. Umbo prosogyrus, displaced anteriorly. Anterodorsal margin diagonally inclined, lunule weak, anterior to resilium. Anterior margin rounded, slightly extended beyond umbo. Posterodorsal margin somewhat straight, almost parallel to ventral margin; both margins connect with nearly vertical posterior margin through rounded corners. Hinge edentulous, with elongated lithodesma. Interior iridescent, with radial lines corresponding to external striae. Adductor muscle scars slightly marked, anterior more than posterior. Palial line noticeable. Ctenidium composed of a reduced outer demibranch and an inner demibranch with ~50 and ~60 branchial filaments, respectively. Inhalant siphon with 12 inner arborescent tentacles on the edge of the aperture and 10 outer small tentacles surrounding it, plus two small dorsal tentacles. Exhalant siphon surrounded by 13 outer small tentacles (seven larger intercalated by six smaller). Byssus present.

Remarks

Lyonsiella abyssicola View in CoL is a comparable species; however, it has 16 tentacles surrounding both siphons, whereas L. tentaculata has 25. The number of tentacles is the same both in the largest individual (MACN-In 44327, 14 mm L) and in the smallest individual (MACN-In 44328, 7 mm L), with a similar size to L. abyssicola View in CoL , hence it can be discarded as a variation attributable to size. Additionally, the new species reaches a larger size and exhibits more radial lines than L. abyssicola View in CoL , (≤ 14 mm and 50 lines vs. 5 mm and 20 lines) ( Fig. 11A, B View Figure 11 ). A clear character visible by SEM is the shape of the microscopic spines. Lyonsiella tentaculata has pyramidal and acuminated spines, whereas L abyssicola View in CoL , Lyonsiella frieli Allen & Turner, 1974 and Allogramma formosa (Jeffreys, 1882) View in CoL , have thinner spines with stellated termination ( Oliveira and Absalão 2010a) ( Fig. 12C, D View Figure 12 ).

Other comparable Lyonsiella species include Lyonsiella subquadrata (Jeffreys, 1882) View in CoL , distinguished by a wider, more prolonged, and ovate anterior margin ( Fig. 11E View Figure 11 ); Lyonsiella perplexa Allen & Turner, 1974 View in CoL , with an angular anterior margin and a lower number of tentacles (~15); Lyonsiella fragilis View in CoL , with a much more horizontal anterodorsal margin, a more prolonged anterior margin, and fewer radial lines (8–18); and Lyonsiella pipoca Oliveira & Absalão, 2010 View in CoL , with short and wider spines oriented irregularly, not radially, and with a few isolated delicate ‘projections’.

Kingdom

Animalia

Phylum

Mollusca

Class

Bivalvia

Family

Lyonsiellidae

Genus

Lyonsiella

Loc

Lyonsiella tentaculata

Pacheco, Leonel I., Teso, Valeria & Pastorino, Guido 2024
2024
Loc

L. tentaculata

Pacheco & Teso & Pastorino 2024
2024
Loc

Lyonsiella tentaculata

Pacheco & Teso & Pastorino 2024
2024
Loc

Allogramma formosa (Jeffreys, 1882)

Machado et al. 2019
2019
Loc

Lyonsiella pipoca Oliveira & Absalão, 2010

Oliveira & Absalao 2010
2010
Loc

Lyonsiella frieli

Allen & Turner 1974
1974
Loc

Lyonsiella perplexa

Allen & Turner 1974
1974
Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF