Myurella Hinds, 1845

Fedosov, Alexander E, Malcolm, Gavin, Terryn, Yves, Gorson, Juliette, Modica, Maria Vittoria, Holford, Mandë & Puillandre, Nicolas, 2019, Phylogenetic classification of the family Terebridae (Neogastropoda: Conoidea), Journal of Molluscan Studies The Malacological Society of London 85 (4), pp. 359-388 : 14-15

Genus Myurella Hinds, 1845

( Fig. 7 A–D)

Type species: Terebra affinis Gray, 1834 ; SD, Cossmann (1896).

Synonyms: Clathroterebra Oyama, 1961 (type species Terebra fortunei Deshayes, 1857 ; OD); Decorihastula Oyama, 1961 (type species Terebra affinis Gray, 1834 ; OD); Terenolla Iredale, 1929 (type species Terebra pygmaea Hinds, 1844 ; OD).

Definition: Primarily defined based on phylogenetic analysis of Modica etal. (2019), comprising species in clade E1 of Modica etal. (2019) and additionally those that show shell morphology, anatomical or genetic characteristics closely comparable with Myurella affinis or any genetically proven member of the clade.

Diagnosis: Diagnostic nucleotide combinations in Table 6 .

Shell: very small to medium-sized, with elongated, with high orthoconoid spire; sculpture of arcuate or undulating ribs, fine and narrow to flat and wide.

Anatomy: Rhynchodeal introvert very large, proboscis, radula and venom gland absent, salivary glands and accessory proboscis structure present in few species.

Distribution: Indo-Pacific; intertidal to upper bathyal depths.

Remarks: In regard to shell morphology, four distinct groups can be recognized:

Myurella affinis group. Shell medium-sized; axial sculpture of low, wide, flattened ribs; subsutural band with elongate nodules separated by punctations, which are also pronounced in interspaces between axial ribs. Similar species that were earlier classified in Myurella , but do not belong in the T. affinis clade (i.e. M. undulata , M. columellaris and M. kilburni ) are here reclassified in the genus Myurellopsis . Typical Myurella species can be recognized by the lower axials and shallower interstices between them. Because of the overall flatter axials, the subsutural band is visually continuous in Myurella ; on the contrary, in Myurellopsis , due to the more elevated ribs, the subsutural band is represented by a row of nodules.

Myurella pseudofortunei group. Shell elongate, of variable size (17–60 mm), with very high, slender spire, evenly convex whorls, indistinct subsutural band and narrow, clearly arcuate axial ribs; interspaces with regular striae. Species of this group exhibit a very distinctive morphotype, which has little in common with other species here attributed to Myurella . Terebrids with this morphology were previously placed in the genus Clathroterebra ; however, in the analysis of Modica etal. (2019), they formed several lineages unrelated to Clathroterebra ; morphological differences between these lineages are still to be studied.

Myurella pygmaea group. Shell small, c. 10 mm; convex spire profile, straight sides to whorls; very short, tapering siphonal canal. Axial sculpture of numerous fine oblique ribs; subsutural band and other spiral elements absent. The group includes one species, M. pygmaea , formerly classified in the monotypic genus Terenolla . The very small but rather solid, finely ribbed shell is easily recognizable among terebrids; its recognition is further aided by the pattern of flesh-colour background with contrasting dark brown spiral line just below the suture.

Myurella amoena group. Shell medium-sized; sculptured with fine to strong ribs, subsutural band defined by line of punctuations, spiral sculpture of narrow grooves or cords. The species of this group form a well-supported clade and exhibit a shallow-water morphotype that was formerly classified in Hastulopsis . Similar deeper-water species are found in Maculauger n. gen., most of which can be recognized by having a row of large spots on the periphery. The other similar species remain within Hastulopsis , comprising a number of Indian Ocean and Japanese endemic species. Species of the M. amoena group have strong but narrow ribs that are notably stronger than spiral elements. In Myurellopsis the ribs are about as strong as in the M. amoena group, but are wider and rounded, with interstices narrower than the ribs. Both Hastulopsis and Maculauger comprise species with axial and spiral elements of comparable strength, resulting in a rather cancellate pattern, and a continuous subsutural band.

Included species:

Myurella affinis (Gray, 1834) 1;

M. amoena (Deshayes, 1859) 1;

M. andamanica (Melvill & Sykes, 1898) 1 ∗;

M. bilineata (Sprague, 2004) 1;

M. brunneobandata (Malcolm & Terryn, 2012) 1;

M. burchi (Bratcher & Cernohorsky, 1982) 1;

M. conspersa (Hinds, 1844) 1;

M. dedonderi (Terryn, 2003) 1;

M. eburnea (Hinds, 1844) 1;

M. flavofasciata (Pilsbry, 1921) 1;

M. fortunei (Deshayes, 1857) 1;

M. mactanensis (Bratcher & Cernohorsky, 1982) 2;

M. mindanaoensis (Aubry, 2008) 1;

M. multistriata (Schepman, 1913) 1;

M. nebulosa (G. B. Sowerby I, 1825) 1;

M. pertusa (Born, 1778) 1;

M. picardali (Aubry, 2011) 2;

M. pseudofortunei (Aubry, 2008) 1;

M. pygmaea (Hinds, 1844) 1 n. comb.;

M. russoi (Aubry, 1991) 2;

M. suduirauti (Terryn & Conde, 2004) 2;

M. wellsilviae (Aubry, 1994) 1.

Figures

Figure 7. Genera Myurella, Maculauger n. gen. and Myurellopsis n. gen. A. Myurella affinis, MNHN-IM-2013-17860, PAPUA NIUGINI Stn PR196, 05◦12.3'S, 145◦48.8'E, 0 m, 39.8 mm. B. Myurella fortunei, MNHN-IM-2013-58677, KAVIENG 2014 Stn DW4468, 02◦45'S, 150◦37'E, 190–472 m, 25.2 mm. C. Myurella amoena, MNHN-IM-2013-46861, KAVIENG 2014 Stn KR02, 02◦37.5'S, 150◦46.5'E, 10–14 m, 24.9 mm. D. Myurella pygmaea, MNHN-IM-2009- 10121, off Lovanono, S Madagascar, 0–5 m, 6.1 mm. E. Maculauger pseudopertusa, MNHN-IM-2009-9954, MIRIKY Stn DW3230, 13◦25'S, 47◦57'E, 71–158 m, 42.9 mm. F. Maculauger campbelli, MNHN-IM-2013-52252, EXBODI Stn CP3836, 22◦08'S, 167◦11'E, 415–420 m, 20.5 mm. G. Myurellopsis undulata, MNHN-IM-2013-10252 PAPUA NIUGINI Stn PR07, 05◦12.5'S, 145◦48.5'E, 2–17 m, 31.9 mm. H. Myurellopsis kilburni, MNHN-IM-2013-12712, PAPUA NIUGINI Stn PS11, 05◦04.7'S, 145◦48.9'E, 0–5 m, 24.8 mm. I. Myurellopsis joserosadoi, MNHN-IM-2013-52369, INHACA 2011 Stn MR13, 25◦59.7'S, 32◦54.5'E, 2–5 m, 17.9 mm.