Anatoma corralae Gofas & Luque, 2021

Gofas, Serge, Luque, Ángel A., Oliver, Joan Daniel, Templado, José & Serrano, Alberto, 2021, The Mollusca of Galicia Bank (NE Atlantic Ocean), European Journal of Taxonomy 785 (1), pp. 1-114 : 40-43

Anatoma corralae Gofas & Luque sp. nov.

urn:lsid:zoobank.org:act:990DA613-088E-477A-97C1-45B6207C044B

Fig. 10

Etymology

The specific name honours Eva Corral Prado, in recognition of her valuable contribution to malacology of this area.

Type material

Holotype GALICIA BANK • 1 sh ( Fig. 10 D ‒ F , 4.0 mm in diameter); 42°41.87′ N, 11°26.71′ W; 1720 m; 8 Aug. 2011; BANGAL 0711 V10; MNCN 15.05 /200138H.

Paratypes GALICIA BANK • 12 spm and 19 sh; same collection data as for holotype; MNCN 15.05 /200138P .

Other material examined

GALICIA BANK • 6 spm, 14 sh; 43°00.12′ N, 11°57.67′ W; 1706 m; 29 Jul. 2011; BANGAL 0711 V2; MNCN • 3 sh; 42°56.77′ N, 11°58.53′ W; 1631 m; 2 Aug. 2011; BANGAL 0711 V5; MNCN .

Description

Shell up to 3.3 mm high and 4.1 mm maximum diameter, with low conical spire, angulate periphery, moderately inflated base and a small umbilicus. Protoconch of ¾ whorl, about 240 µm in maximum diameter, terminated by a slightly flaring edge; protoconch sculpture of irregular granules which tend to form spiral lines towards the periphery. Teleoconch I (until the beginning of the selenizone) about 1.1 whorl, with about 45‒50 faint axial riblets, more indistinct in their adapical part, and with a distinct spiral thread abutting on the beginning of the selenizone. Teleoconch II with 2 to 2.5 whorls, separated by a deep suture, and the space between suture and selenizone (the “sutsel” according to Geiger 2012) somewhat wider than the latter. Marked peripheral keel, accentuated by the abapical edge of selenizone, which is more prominent than the adapical edge. Selenizone delimited by two narrow lamellae, inside with weakly marked growth stages. Adapical surface of whorls with axial riblets and very thin spiral threads; the riblets arched, much narrower than the interspaces, uneven and very irregularly spaced, attenuated upon reaching the selenizone, about 70 on the first whorl of teleoconch II, about 110‒120 on the last whorl; spiral threads, about 20 in the last half-whorl, attenuated in the part that borders the selenizone. Base regularly convex, with sculpture of axial riblets and spiral threads similar in density and appearance to those of the adapical part; the ribs are somewhat flexuous and prolonged inside the umbilicus; the spiral cords, about 35‒40, are somewhat weaker towards the periphery. Umbilicus small, without apparent funiculus. Aperture rounded, interrupted by an incision which extends on about ¼ of the last whorl and narrows at the edge. Colour white.

Distribution

So far only known from deep-water off the GB.

Remarks

Anatoma corralae sp. nov. is most similar to A. schiottei Høisaeter & Geiger, 2011 , described from the Norwegian Sea, and was mistaken for it in the preliminary report of INDEMARES BANGAL ( Gofas et al. 2014b). It differs in being larger (4 mm, compared to 2.25 mm in A. schiottei ), having a longer teleoconch I (more than one whorl vs 0.75 whorl) with much more numerous axial riblets (50 vs 15), and in lacking a funiculus in the umbilicus (conspicuous in A. schiottei , see Høisaeter & Geiger 2011: fig. 48). Nevertheless, both species share the same angular outline, the microsculpture of the protoconch with granules tending to be aligned along spiral lines, and the shape of the edge of the protoconch, which is only slightly flaring and has no secondary thickening. The protoconch microsculpture, unusual in the genus, suggests that they may be related.

Among the species locally present, Anatoma umbilicata , which is found together in the same hauls, differs clearly by its broad umbilicus and in being practically smooth. Anatoma tenuisculpta is quite similar to Anatoma corralae sp. nov. in size and outline, but differs in having a much coarser axial sculpture forming a regular lattice with small nodules at the intersections of riblets and spiral threads; it also has a much shorter teleoconch I, hardly over half a whorl. Anatoma richardi , which is found on GB but not in the same depth interval, also has such coarser sculpture, and its last whorl is more ample and its suture is not so far below the selenizone.

“Skeneimorph” species

This informal group includes the members of the family Skeneidae W. Clark, 1851 but also members of other Vetigastropod families including several genera of uncertain phylogenetic affinity ( Hoffman et al. 2020c) which have been shown by Kano et al. (2009) to be related to the superfamily Seguenzioidea or to other non-vetigastropod clades, like neomphalids or heterobranchs ( Haszprunar et al. 2011, 2016).

Key to the “skeneimorph” species found in the GB

1. Shell smooth and glossy, with reduced or filled umbilicus ............................................................... 2

– Shell smooth, but not glossy, or sculptured, with definite umbilicus ............................................... 3

2. Shell nearly as high as broad .............. Cirsonella romettensis (Granata-Grillo, 1877) ( Fig. 14A–C )

– Shell definitely broader than high (h/w less than 0.7) ........................................................................ ........................................... Seamountiella azorica (Dautzenberg & H. Fischer, 1896) ( Fig. 14D–F )

3. Axial sculpture obvious .................................................................................................................... 4

– No axial sculpture.............................................................................................................................. 5

4. Axial sculpture of narrow, widely spaced ribs .................................................................................... .............................................................. Vetulonia paucivaricosa (Dautzenberg, 1889) ( Fig. 13F–H )

– Axial sculpture of tightly packed wrinkles ......................................................................................... .............................................. “ Skenea ” ponsonbyi (Dautzenberg & H. Fischer, 1896) ( Fig. 15E–F )

5. Surface, at least around the umbilicus, with a distinct sculpture ...................................................... 6

– No conspicuous sculpture, or only subsutural and/or periumbilical keel ....................................... 13

6. Sculpture essentially spiral ............................................................................................................... 7

– Sculpture different ............................................................................................................................ 9

7. Spiral sculpture only surrounding the umbilical area, sometimes a subsutural cord at least on the early whorls ..................................................................................... Moelleriopsis sp. ( Fig. 15C–D )

– Spiral sculpture all over the shell ...................................................................................................... 8

8. Shell yellowish, sculpture of small but definite spiral ridges ............................................................. ............................................................................. Rugulina fragilis (G.O. Sars, 1878) ( Fig. 14G–H )

– Shell whitish, sculpture of minute spiral threads ................................................................................ ....................................................................... Anekes spiralis Gofas & Luque sp. nov. ( Fig. 17A–H )

9. Sculpture of oblique threads, which form a mesh ......................................................................... 10

– Sculpture of minute granules all over the shell (may be very tenuous) .......................................... 12

10. Sculpture forming an oblique mesh all over the shell .....................................................................11

– Sculpture tenuous, restricted to apical and umbilical areas ................................................................ ................................................................................. Anekes paucistriata Warén, 1992 ( Fig. 16F–K )

11. Shell conical, aperture height about half of total height ..................................................................... .................................................................................... Anekes affinis (Jeffreys, 1883) ( Fig. 16A–E )

– Shell globose, aperture height about two thirds of total height .......................................................... .................................................................................... Granigyra inflata ( Warén, 1992) ( Fig. 17I–L )

12. Aperture very broad, more than half the shell diameter ..................................................................... ............................................................................. Granigyra pruinosa (Jeffreys, 1883) ( Fig. 15G–J )

– Aperture diameter less than half the shell diameter ............................................................................ ................................................................................ Granigyra tenera (Jeffreys, 1883) ( Fig. 15K–L )

13. Spiral keel present at least on the first teleoconch whorl ................................................................ 14

– Whorls convex, with no spiral keel even around umbilicus ............................................................... .............................................................................. Akritogyra similis (Jeffreys, 1883) ( Fig. 15A–B )

14. Abapical keel sharp and distant from the umbilicus ...... Trenchia biangulata Rubio & Rolán, 2013

– Abapical keel blunt and situated within the umbilicus, or at its edge ............................................ 15

15. Shell higher than broad, subsutural keel on most whorls ................................................................... .......................................................................................... Mikro scalaroides ( Rubio & Rolán, 2013)

– Shell wider than high, subsutural keel fading on last whorls ............................................................. ............................................................................. Mikro minimus (Seguenza G., 1876) ( Fig. 14I–L )

Figures

Fig. 10. Anatomidae 4. Anatoma corralae Gofas & Luque sp. nov. A–C. Paratype (MNCN 15.05/200138P), BANGAL 0711, V10, 1720 m, 4.0 mm diameter. D–F. Holotype (MNCN 15.05/200138H), SEM micrograph, BANGAL 0711, V10, 4.1 mm diameter. E–F. Details of early teleoconch whorls and protoconch of the holotype. G–H. Shell and detail of the protoconch, SEM micrographs, from BANGAL 0711, V5, 1631 m, 2.1 mm diameter. Scale bars: A–D, G = 1 mm; E = 200 µm; F, H = 100 µm.

Fig. 14. Skeneimorph species 1. A–C. Cirsonella romettensis (Granata-Grillo, 1877), SEAMOUNT 1, DW116, 985–1000 m, 2.3 mm. D–F. Seamountiella azorica (Dautzenberg & H. Fischer, 1896), SEAMOUNT 1, DW108, 1120–1125 m, 4.2 mm. G–H. Rugulina fragilis (G.O. Sars, 1878), BANGAL 0711, V2, 1706 m, 2.8 mm. I–J. Mikro minimus (Seguenza, 1876), BANGAL 0711, V5, 1631 m, 0.95 mm. K–L. Mikro minimus, SEM micrograph, same shell, and detail of protoconch and apical whorls. Scale bars: A–K = 1 mm: L = 100 µm.

Fig. 13. Seguenzioidea and Colloniidae. A–B. Asthelys munda (Watson, 1879), BANGAL 0711, DR15, 1410 m, 3.2 mm. C–E. Basilissopsis watsoni Dautzenberg & H. Fischer, 1897, BANGAL 0711, DR12, 1585 m, 1.8 mm. F–H. Vetulonia paucivaricosa (Dautzenberg, 1889), BANGAL 0711, V6, 909 m, diameter 3.3 mm. I–J. Adeuomphalus sinuosus (Sykes, 1925), BANGAL 0711, DR12, 1585 m, diameter 1.5 mm. K–L. Cantrainea globuloides (Dautzenberg & H. Fischer, 1896), SEAMOUNT 1, DW116, 985–1000 m, 4.7 mm. Scale bars = 1 mm.

Fig. 15. Skeneimorph species 2. A–B. Akritogyra similis (Jeffreys, 1883), BANGAL 0711, V5, 1631 m, diameter 2.2 mm. C–D. Moelleriopsis sp., SEAMOUNT 1, DW108, 1120–1125 m, 2.7 mm. E–F. “Skenea” ponsonbyi (Dautzenberg & H. Fischer, 1896), BANGAL 0711, V9, 1671 m, 3.2 mm. G–H. Granigyrapruinosa (Jeffreys, 1883), BANGAL 0711,V10, 1720 m, 3.7 mm.I–J. SEM micrograph, same shell, and detail of microsculpture. K–L. Granigyra tenera (Jeffreys, 1883), BANGAL 0711, V10, 1720 m, 2.3 mm. Scale bars: A–I, K–L = 1 mm; J = 200 µm.

Fig. 17. Skeneimorph species 4. A–H. Anekes spiralis Gofas & Luque sp. nov. A–B. Holotype (MNCN 15.05/200139H), BANGAL 0711, V5, 1631 m, diameter 1.7 mm.C–D. SEM micrograph of the holotype. E. Apical view, protoconch and early teleoconch whorl of the holotype. F. Detail of the microsculpture of the adapical part of the last whorl. G. Detail of the umbilical area of the holotype. H. Paratype (MNCN 15.05/200139P), SEM micrograph, same locality, 2.0 mm. I–J. Granigyra inflata (Warén, 1992), BANGAL 0711, V5, 1631 m, diameter 1.8 mm. K–L. Same shell, SEM micrograph and detail of the microsculpture of the last whorl. Scale bars: A–D, H–K = 1 mm; E, G, L = 200 µm; F = 50 µm.

Fig. 16. Skeneimorph species 3. A–B. Anekes affinis (Jeffreys, 1883), BANGAL 0711, V5, 1631 m, diameter 1.4 mm. C–E. SEM micrograph, same specimen, and detail of protoconch and apical whorls, showing the characteristic “Anekes sculpture”. F–G. Anekes paucistriata Warén, 1992, BANGAL 0711, V5, 1631 m, live taken specimen, diameter 1.9 mm. H–K. SEM micrograph of another shell, detail of protoconch and apical whorls, and detail of the umbilical area. Scale bars: A–D, F–I = 1 mm; E, J–K = 200 µm.