Falsimacme kobelti ( Strebel, 1905 ) Strebel, 1905

Pastorino, Guido, 2016, Revision of the genera Pareuthria Strebel, 1905, Glypteuthria Strebel, 1905 and Meteuthria Thiele, 1912 (Gastropoda: Buccinulidae) with the description of three new genera and two new species from Southwestern Atlantic waters, Zootaxa 4179 (3), pp. 301-344 : 323-326

Falsimacme kobelti ( Strebel, 1905) new comb.

Figures 15 A–L, 16A–D

Euthria Glypteuthria kobelti Strebel, 1905: 632 , pl. 21, figs. 15, 15a.

Euthria Glypteuthria kobelti Strebel. Melvill & Standen, 1914: 122 ; Powell, 1951: 138; 1960: 148. Meteuthria martensi Strebel. Castellanos, 1992: 20 , pl. 1, fig. 9 only; Linse, 2002: 101, pl. 12, figs. 9.1.1-93/96 (non Strebel, 1905).

Type material. All material from Strebel’s collection housed in ZMH should be regarded as syntypes: 1 spm., Puerto Bridges, 7 fms. [12.8 m] depth, (M 164) (Number 9 in Strebel, 1905: 632,), this specimen ( Fig. 14 A–C) is here designated as lectotype in order to preserve stability of nomenclature, in agreement with ICZN article 74. 1 spm., Mollyneux Sound, 27 fms. [49.3 m] depth (Number 1 in Strebel, 1905: 632); 5 spms., Puerto Eugenia, 10–15 fms.

[18.2–27.4 m] depth, (SE 6229 (768)) (Number 5 in Strebel, 1905: 632); 2 spms., Hope Harbor, 6–10 fms. [10.9–18.2 m] depth, (SE 6198 (44)) Number 6 in Strebel, 1905: 632); 1 spm., Puerto Harris, 15 fms. [27.4 m] depth, (SE 6190) (Number 7 in Strebel, 1905: 632); 1 spm., Ushuaia, 12-15 fms. [21.9–27.4 m] depth, (SE 6149 (789)) (Number 8 in Strebel, 1905: 632); 2 spms., Puerto Pantalón, Tierra del Fuego, 7 fms. [12.8 m] depth, (M189) (Number 10 in Strebel, 1905: 633); 2 spms., Picton Is., Banner Cove, 3fms. [5.4 m] depth, (M 168) (Number 12 in Strebel, 1905: 633).

Type locality. Here restricted to Puerto [Islas] Bridges , Beagle Channel , Tierra del Fuego.

Description. Shell small, up to 10 mm in height, fusiform, of 6 slightly convex, distinct whorls, color red, brownish, bright, outside and inside; protoconch ( Figs 15 I–K) of 1 1/2 convex whorls, translucent, entirely smooth but faint growth lines are present, transition to teleoconch weakly defined; suture impressed, somewhat channelled; aperture elliptical, labrum thick; siphonal canal deep, oblique and long; parietal callus thin; growth lines closely spaced over the entire shell; spiral ornamentation of thick threads, 3 on the first two whorls, 4 to 5 on the others; axial sculpture of 14 to 15 varices, which develop nodes when crossing the spiral threads; periostracum thin and translucent.

Operculum ( Fig. 15 L) thick, pale yellowish, elliptical shape, nucleus subterminal, attachment area central.

Radulae ( Figs 16 A–D) with rachidian teeth absent; laterals somewhat rectangular, Prosipho -like with the outer portion of the basal plate produced into a typical “handle” that is nearly half the width of the tooth, with 5 to 8 cusps pointing posteriorly. The number and size of the cusps are sometimes different in both laterals of the same row and decrease in size from the center to the sides of the radula.

Material examined. Argentina: 25 spms., Puerto Deseado , Santa Cruz, (MACN-In 17757); 2 shells, 55°07’S, 66°33W, 82 m depth, (MACN-In 23944-1); 3 spms. , Bahía Laura , Santa Cruz, (MACN-In 36951); 1 spm. , Cabo Blanco , Santa Cruz, (MACN-In 17843-1); 1 shell, 52°40’S, 74°58’W, Mouth of Strait of Magellan, 64 m depth, St. 960, Cr. 11, RV ELTANIN, ( USNM 894557 ) ; 3 shells 52°41’S, 74°35’W, Strait of Magellan,, 247 m depth, (USNM 898755); 2 shells, 52°40’S, 74°58’W, 64 m depth, (USNM 898866); 1 shell, 53°48’42”S, 70°24’06”W, 18 m depth, (USNM 887620); 1 shell, 54°48’S, 64°42’W, Staten Island, 18 m depth, ( USNM 898349 ) ; 1 shell, 54°48’S, 64°42’W, Le Maire Strait, 18 m depth, (USNM 887624); 5 spms., Ushuaia, (MACN-In 40508); 1 spm., Ushuaia, (MLP4963-2).

Chile: 1 shell, Punta Arenas, (MACN-In 8648-6).

Distribution. Puerto Deseado, Santa Cruz province in the north, to Tierra del Fuego Is. including Beagle Channel, Straits of Magellan and, Malvinas and Lively Is. ( Melvill & Standen, 1914).

Remarks. There are very few citations of F. kobelti after the original description in the Magellanic literature, perhaps because of its similarity to Argeneuthria euthrioides and Glypteuthria meridionalis . It was originally included by Strebel in the genus Glypteuthria , an assignment later followed by Powell (1951: 138, 1960: 147) and Melvill and Standen (1914) who cited shells collected from Lively Is. The radula, here illustrated for the first time, has no rachidian teeth and the laterals are quite different from any described genus, despite certain resemblance to those of Anomacme smithi Strebel (according to the material studied and illustrated here in Figures 10A–E and by Thiele (1912, pl. 16, fig. 14), later repeated by Powell (1951: 193)). The peculiar radula of A. smithi has a tricuspid rachidian. Castellanos (1992) included F. kobelti as a synonym of M. martensi despite clear radular differences that were not recognized by this author. In addition, the shell of F. kobelti has a longer, more slender spire and the whorls are distinctive because of the presence of a sutural furrow. Also, there are usually three spiral threads in the first two whorls but four in M. martensi . Finally fresh shell colour is also distinctive, brownish and whitish respectively. Similarities with A. euthrioides are discussed under this species.

Figures

FIGURE 14. Meteuthria batialis n. sp. A – B. Two views of the radula, scale bars: A = 25 µm, B: 100 µm. C. External and internal view of the operculum, scale bar = 1 mm. D. Penis, critical point dried, scale bar = 500 µm.

FIGURE 15. Falsimacme kobelti (Strebel, 1905). A – C. Euthria Glypteuthria kobelti Strebel, 1905, lectotype, Puerto Bridges, M 164. D – F. Mollyneux Sound, paralectotype. G – H. Puerto Deseado, Santa Cruz, MACN-In 17757; Scale bar = 3 mm. I – K. Three views of the protoconch, scale bar = 300 µm. L. External and internal view of the operculum, scale bar = 500 µm.

FIGURE 16. Falsimacme kobelti (Strebel, 1905). A – D. Four views of the radula, scale bars A = 50 µm; B: 30 µm; C: 20 µm; D: 10 µm.

FIGURE 10. A – E. Anomacme smithi Strebel, 1905. A. MACN-In 35381, scale bar = 2 mm; B. radula, scale bar = 50 µm; C. detail of the marginal teeth, scale bar = 20 µm; D. operculum, external view, scale bar = 500 µm, E. protoconch, scale bar = µm. F – J. “ Anomacme ” multituberculata Castellanos, Rolán & Bartolotta, 1987; F. protoconch, USNM 870453, same scale bar as E; G. operculum, external view, scale bar = 500 µm; H: radula, scale bar = 100 µm; I. detail of the radula, scale bar = 10 µm; J. USNM 870453, scale bar = 1 mm.