Leiosolenus (Labis) patagonicus (d’Orbigny, 1846 in 1834-1847)

Delfino, Marina Inés & Signorelli, Javier Hernán, 2022, Leiosolenus (Labis) patagonicus (Bivalvia: Mytilidae) from Argentinean sea, taxonomic revision and anatomical notes, Papéis Avulsos de Zoologia 62, pp. 1-12 : 3-5

Leiosolenus (Labis) patagonicus (d’Orbigny, 1846 in 1834-1847)

( Figs. 2 A-K, 3A-G, 4A-I)

Lithodomus patagonicus d′Orbigny, 1846 in 1834-1847: 650, pl. 82, figs. 24, 25, pl. 85, figs. 19-20 – Rochebrune & Mabille, 1889: 119.

Lithophaga patagonica d′Orbigny – Dunker, 1882: 9, pl. 6, figs. 6-7; Ihering, 1900: 96-97; Carcelles & Williamson, 1951:328; Castellanos,1957:9,10,pl.2,fig.9,pl.4fig.10; 1970: 213, pl. 17, fig. 10; Bernard, 1983: 21; Pastorino, 1995: 13, pl. 3, fig. 18a, b; Scarabino, 2003: 232; Scarabino et al., 2006: 62; Rios,2009: 490,fig. 1375.

Lithodomus patagonica d′Orbigny – Charcot et al., 1903 -1905: 16.

Lithophaga (Diberus) patagonica d′Orbigny – Carcelles, 1944: 272, pl. 6, figs. 58-63.

Lithophaga (Labis) patagonica d′Orbigny – Turner & Boss, 1962: 102-104, pl. 68, figs. 1-4; Rios, 1966: 29.

Leiosolenus (Labis) patagonicus d′Orbigny – Huber, 2010: 121.

Leiosolenus patagonicus d′Orbigny – Zelaya, 2016: 253.

Type locality: Ensenada de Ross, Río Negro province, Argentina.

Type material: NHMUK 1854.12.4.790, holotype. The examined material consists of the substrate where the valves studied by d′Orbigny were found. No valves were found into the type cabinet ( Figs. 2 A-C).

Additional material examined: Argentina: Buenos Aires coast: MACN 15801 , 25 complete specimens, subtidal. MACN 15223 , 1 empty shell ; Santa Clara del Mar : MLP 4206 , 16 empty shells and 13 complete specimens ; Mar del Plata : MACN 9361 , 4 empty shells ; MACN 16869 , 1 empty shells ; MACN 12201-1 , several valves with calcareous conical tubes ; MACN 2399-1 , 1 complete specimen ; Miramar : MLP 1246 , 2 complete specimens ; MACN10036 , 1 empty shell ; MACN29444 , 20 empty shells ; MACN 13107-1 , 9 empty shells ; Necochea : MACN 9368-2 , 1 empty shell ; Puerto Quequén : CNP-INV 2864, 20 complete specimens,intertidal ; MACN 18506 , 13 empty shells and 30 complete specimens. Río Negro , Caleta de los Loros: MACN 39037 , specimens extracted from oysters ; Bahía Creek : MLP 4071-3 , several complete specimens ; San Matías gulf: MACN 21284 , 2 complete specimens ; MACN 30799 , 1 complete specimen ; MLP 4169 , 2 empty shells ; CNP-INV 2870,8 empty shells. Chubut, Punta Norte : MACN 11504 , 3 empty shells with calcareous conical tubes ; MACN11504 b,shells with calcareous conical tubes ; San José gulf: MACN 24475 , 4 empty shells, MACN 26488 , 4 complete specimens ; MACN 9179-1 , 5 empty shells ; Villarino : CNP-INV 2866, 2 empty shells, intertidal ; CNP-INV 2865, 4 empty shells, intertidal; CNP-INV 2863, 19 empty shells, intertidal; Isla de los Pájaros : MLP 3777 , 4 empty shells and 1 complete specimen ; Punta Gales: CNP-INV 2876, 3 empty shells, intertidal ; CNP-INV 2877, 14 empty shells, intertidal; CNP-INV 2875, 15 empty shells; Bahía Fracasso : CNP-INV 2883, 7 empty shells, intertidal ; Puerto Pirámides : MLP 4233 , 4 empty shells and 2 complete specimens ; Punta Pardelas : CNP-INV 2892, 2 empty shells, intertidal ; CNP-INV 2893, 1 specimen, intertidal; CNP-INV 2871, 7 complete specimens; MLP 50053 , 10 complete specimens ; MLP 50054 , 6 empty shells and 2 complete specimens ; MLP 50056 , 1 complete specimen ; Puerto Madryn : MLP 1933 , 5 empty shells and 2 complete specimens ; MLP 1939 , several complete specimens ; MLP 4915 , 2 empty shells and 1 complete specimen ; MACN 10336 , 4 complete specimens within coral algae (Order Corallinales ) ; MACN 23242 , 8 empty shells ; MACN 9172-8 , 4 empty shells and 1 complete specimen ; MACN 9219-1 , 2 empty shells ; MACN 9281-1 , 1 complete specimen ; Punta Cuevas : CNP-INV 2884, 2 articulated shells and 6 complete specimens, intertidal ; Punta Este : CNP-INV 2873, specimens with calcareous conical tubes, intertidal ; CNP-INV 2885, 6 pairs of articulated shells, intertidal; CNP-INV 2878, 33 complete specimens and habitats, intertidal; CNP-INV 2881, 5 complete specimens, subtidal; Paraná Beach : CNP-INV 2861, several specimens, intertidal ; CNP-INV 2887, 2 complete specimens, intertidal; CNP-INV 2888, 1 complete specimen, intertidal; CNP-INV 2880, 1 complete specimen, intertidal; Cerro Avanzado : MLP 13083 , 20 complete specimens ; CNP-INV 2862, 25 complete specimens, intertidal; CNP-INV 2890, 1 complete specimen, intertidal; CNP-INV 2891, 1 empty shell, intertidal; CNP-INV 2872, several specimens, intertidal; Cracker Bay : MLP 13019 , 2 complete specimens ; MACN 26489 , several specimens ; Punta Ninfas : CNP-INV 2886, 6 complete specimens, intertidal ; CNP-INV 2882, 1 complete specimen, intertidal; Comodoro Rivadavia : MACN 6840 , 8 complete specimens. Santa Cruz, Puerto Deseado: MACN 33643 , 1 empty shell ; Puerto San Julián : CNP-INV 2889, 2 complete specimens, intertidal ; CNP-INV 2868, 20 complete specimens, intertidal; CNP-INV 2869, 1 complete specimens, intertidal.

Diagnosis: Shell oval, medium size, with smooth calcareous projections behind posterior end; calcareous depositions on the outer surface of the shell with a granular appearance.

Description

Shell – equivalve, thin, fragile, oval, rounded ends, circular in cross section, length up to 40 mm. (MACN 15801); umbo prosogyrate, anterior, poorly developed; dorsal margin slightly arched, ventral margin straight, poorly defined concentric and irregular growth lines, covered by calcareous granular depositions on the posterior and ventral area of the external surface, hiding juvenile ridges; smooth calcareous projections extending beyond the limits of posterior end of valves ( Figs. 2H, J ); inner surface blue to violet, vitreous luster; pallial sinus and scar adductor muscles poorly visible; hinge plate adonta, extremely small teeth; opisthodetic ligament ( Figs. 2F, H ).

Internal anatomy – mantle folds with purple coloration ( Fig. 3A ); middle mantle fold smaller than others; siphons well developed, different in size and shape, usually with a purple coloration ( Figs. 3 B-D); fused at the base, excurrent siphon smaller than incurrent, free of tentacles over the opening ring; incurrent siphon free of tentacles, opened along ventral edge, with a basal siphonal valve, flap-like with finger-like edges, placed at the base ( Fig. 3E ); some specimens provided with a tubular structure, over the edge of incurrent siphon, which secreted a whitish and viscous substance ( Figs. 3 F-G); two pairs of demibranchs along antero-posterior axis; internal and external demibranchs equals in length, filibranch type B (1) from Atkins (1937) ( Figs. 4 A-C), filaments connected by vascular connections give reticulate appearance ( Fig. 4B ); food groove present at distal border of each demibranch ( Fig. 4C ); labial palps longer than wide, triangular in shape, smooth external surfaces,internal provided of transverse folds ( Figs. 4 D-E); foot poorly developed, longer than wide ( Figs. 4 F-H); anterior adductor muscle smaller than posterior, lenticular shape, closely located to dorsal edge; posterior adductor muscle oval ( Fig. 3A ); byssal pit relatively deep, with golden filaments of byssus, placed posteriorly to the foot ( Figs. 4 H-I).

Figures

Figure 2. L.patagonicus.Shell morphology.(A-C)substrate belonging to the holotype (NHMUK 1854.12.4.790,not found);(D-K) internal and external view of shell (CNP-INV 2887).

Figure 3. L.patagonicus.Mantlecavity organsof the specimendepositedas CNP-INV2873.(A) generalviewof the organismafterremoval of theleft valve;(B-D) detail of the siphon morphology;(E)basal siphonal valve.(F-G) tubular structure secretingmucous substance.Abbreviations:AAM = anterior adductor muscle;BSV = basal siphonal valve;ES = excurrent siphon;IS = incurrent siphon;PAM = posterior adductor muscle.

Figure 4. L. patagonicus. Mantle cavity organs of the specimen deposited as CNP-INV 2873.(A) ventral view,observing the foot and gills on sides;(B) external and internal demibranch details;(C) detail of food groove over the distal edge of outer demibranch;(D-E) labial palps;(F-G) morphology of the foot;(H-I) byssus gland. Abbreviations:BF = byssal filaments;BG = byssus gland; F = foot; FG = Food groove; ID = inner demibranch; LILP = left inner labial palp;LOLP = left outer labial palp;OD = outer demibranch;RILP = rightinner labial palp;ROLP = right outer labial palp.