Mitromorpha (Mitrolumna) wilhelminae

Amati, Bruno, Smriglio, Carlo & Oliverio, Marco, 2015, Revision of the Recent Mediterranean species of Mitromorpha Carpenter, 1865 (Gastropoda, Conoidea, Mitromorphidae) with the description of seven new species, Zootaxa 3931 (2), pp. 151-195 : 169-171

Mitromorpha (Mitrolumna) wilhelminae (van Aartsen, Menkhorst & Gittenberger, 1984)

( Figs 14 A–K; 15A–I; 16A–E; 17; 27I –L; 28D, E)

Mitrolumna wilhelminae van Aartsen, Menkhorst & Gittenberger, 1984: 42, fig 205 Mitrolumna crenipicta Mifsud, 1993:15 , 16 non Dautzenberg, 1889

Mitromorpha (Mitrolumna) cf. karpathoensis Mifsud, 2001:15 , pl. 2, fig. 27 non Nordsieck, 1969

Type material: Holotype RMNH 55669 (H. 7.7 mm); paratypes, from the type locality, coll. van Aartsen 9937/7, 17627/>25; BMNH /2; coll. Menkhorst, Krimpen/>25; MNHN /2; RMNH 55679/10; USNM /2.

Type locality: Spain, province of Cadiz, Getares (4 km S. of Algeciras).

Other material examined. Spain: Getares South, 0.30 m under rocks, 6 lv (IN); Getares, 15 m, 12 sh (AR); Punta Carnero, Getares, 15 m, 5 sh (SB-MS); Gibraltar, 1 sh ( MCZR, coll. Monterosato M- 21-17319) ( Fig. 15 H, I); Alboran Is., “Mediterraneo 92” stn ALB C 35° 56’ 10” N 003° 01’ 48” E, 17 m, bioclastic sand, 17 sh (typical) + 6 sh (white) (MO); Alboran, Stn ‘Alb 926’, 17 m, 3. viii.1992, 11 sh (white) (IN); Alboran Is., 150 m, red coral fishing by-catch, 3 sh (CS), 80–150 m, 1984, 27 sh (CS); Chafarinas Islands, 120–180 m, 2 sh (IN); Alboran Sea, 87 sh (PC). Morocco: Cala Iris, Morocco, 5 m, bioclastic sand, 18. vi.1993, 1 sh (MO).

Distribution and habitat. Alboran Sea (Western Mediterranean). Recent. Empty shells from the intertidal down to 400 m depth in bioclastic sediments. Morph A, live specimens collected amidst photophylous algae (1–30 m), kelp (30–60 m), more rarely on hard coralligenous bottoms (60–250 m) ( Peñas, Rolán, Luque, Templado, Moreno, Rubio, Salas, Sierra & Gofas (2006). Shells of morph B from deeper waters (80–180 m), on red coral bottoms ( Gofas, Moreno & Salas 2011: 329). Found sympatric with M. columbellaria .

Description. Shell of medium size for the genus ( Figs 14 A–K; 15A–I; 16A; 27I –L), height 5.8–8 mm, width 3.1–3.85 mm. solid, fusiform, biconic, slender, H/W=2.064–2.133. Protoconch paucispiral ( Figs 16B,C ; 28D, E) shiny, of 1.3–1.4 convex whorl, d 0.20–0.225 mm, Do 0.35–0.40 mm, DM 0.55–0.575 mm, h 0.45 mm, sculptured by sparse microgranules. Protoconch-teleoconch boundary well marked, flexuose, opisthocline. Teleoconch of da 5–5.3 barely convex whorls. Sculpture starting with 3 spiral cordlets crossed by 14–15 opisthocline axial ribs on the first whorl. Additional spiral cordlets between the adapical ones, and between the suprasutural one and the suture. Axial ribs present on all whorls (18 weak, orthocline or slightly prosocline axials on the penultimate whorl) except the last one, and producing nodules at the intersection with the spirals. Last whorl sculptured over the entire surface by 20–23 weak spiral cordlets, flat, equidistant, of equal size, as broad as the interspaces, of which 4–6 above the aperture. Two columellar folds, equal in size. Growth lines visible over the entire surface. Outer lip not sharp, thickened internally with 7 denticles, the second or third posterior more pronounced. Anal sinus very shallow. Siphonal canal short, and wide. Coloration, beige in the background with 16 chestnut-brown spiral stripes narrower than the spiral cordlets. Cordlets I, IV, VI, VIII, XI, XIV and XVI of the same background color. Often, whitish subsutural blotches in correspondence with the axials. Protoconch brown with lighter spiral suprasutural band. Aperture and columella lighter. Soft parts white translucid, with black eyes ( Peñas et al. 2006: 131, figs442,443).

Remarks. M. wilhelminae , known so far only from the area of Gibraltar and the Alboran Sea, is easily recognized by its shell inflated even in the first whorls, nearly keeled at the periphery, with weak spiral and axial sculpture, a light background color, with numerous fine spiral brown striae, often with bright coloration darker on the base, and blotches at the periphery. A peculiar deep water morph (corresponding to the western cline of M. karpathoensis sensu Mifsud 2001 ) is recognizable by its stouter outline, its usually more numerous spirals on the last whorl (34) and above the aperture (8), and its peculiar coloration with a beige-pinkish background with some darker spirals, and a darker peripheral band (corresponding to 3–4 spirals) with two spiral series of whitish rounded spots ( Mifsud 1993, 2001; Rolán & Boyer 2001; Gofas et al. 2011).

Mitrolumna wilhelminae is very similar to M. columbellaria , both having 4–6 spirals above the aperture (with the exception of the deep water morph of wilhelminae , which can have up to 9); and both showing occasional white specimens, so that Vera-Peláez (2002) has synonymised the two taxa. However, the typical M. wilhelminae is distinguished from M. columbellaria in its more convex outline, more evident in the juveniles (which often are almost keeled), in its weaker sculpture, the coloration with spiral striae, and the white color of the soft parts ( v. the yellowish-orange color of columbellaria ). The deep water morph is even more distinct, given the higher number of spirals above the aperture, and the more brilliant coloration of the shell. M. olivoidea is distinguished from M. wilhelminae ( Figs 8 A–O; 9A–E; 27G) in its chromatic pattern, monochrome or with alternate darker and lighter blotches at the periphery, and in the higher number of spirals above the aperture (8– 11 v. 5–6 in wilhelminae ) (vd. Table I). See under M. karpathoensis and M. nofronii n. sp. for the distinction with these species.

Figures

FIGURE 8. Mitromorpha olivoidea (Cantraine, 1835). A – B. lectotype of Mitra olivoidea Cantraine, ‘ Mediterraneo’, H = 8.3 mm (IRSN, IG 3354); C – D. Holotype of Mitromorpha melitensis (Mifsud, 1993), Malta, H = 9 mm (MZB- 011673); E – H. Cala Gonone, Sardegna, Italy, H = 9.2 mm (BA); I. Marina di Camerota 90 m, Italy, H = 9 mm (CS); J – K. Elba Is., Italy, H = 7.2 mm (MCZR, M- 21 - 17319); L-M. Palermo, Italy, H = 7.3 mm (MCZR, M- 21 - 17319); N – O: S. Vito lo Capo, Italy, H = 7.75 mm (MCZR, M- 21 - 17319).

FIGURE 14. Mitromorpha wilhelminae (Aartsen, Menkhorst & Gittenberger, 1984). A – C. Alboran Is., Spain, 17 m, H = 7.9 mm (MO); G. Alboran Is., Spain, 17 m, close-up of the first whorls (MO); D – F. Alboran Is., Spain, 17 m, juvenile, H = 3.55 mm (MO); H. Alboran Sea, Spain, white specimens, H = 7.4 mm (PC); I. Alboran Is., Spain, 17 m, white specimens, H = 6.6 mm (IN), J – K. Alboran Is., Spain, 17 m, juvenile white specimen, H = 4.6 mm (IN).

FIGURE 15. Mitromorpha wilhelminae (Aartsen, Menkhorst & Gittenberger, 1984), morph A. A – C. Chafarinas Islands, Spain, H = 7.5 mm (IN); D. Alboran Is., Spain, 80 – 150 m, H = 8.45 mm (CS); E. Alboran Is., Spain, 80 / 150 m, H = 7.45 mm (CS); F. Chafarinas Islands, Spain, close-up of the first whorls (IN); G. Alboran Is., Spain, 80 / 150 m, H = 2 mm (CS); H, I. Gibraltar, UK, H = 8.2 mm (coll. Monterosato, MCZR, M- 21 - 17319).

FIGURE 16. A – E. Mitromorpha wilhelminae (van Aartsen, Menkhorst & Gittenberger, 1984), (SEM), Alboran Is. A. specimen juv. H. 2.6 mm; B, C. First whorls; D, E. Radular tooth. Scale bars: 1 mm (A), 100 µm (B), 500 µm (D), 10 µm (D), 50 µm (E).