Marshallora monteiroi ( Rolán & Fernández-Garcés, 2015 ) Fernandes, 2024

Fernandes, Maurício Romulo, 2024, Triphoridae (Gastropoda) from Martinique sampled by the MADIBENTHOS expedition, with notes on shallow-water species from Guadeloupe, Zoosystema 46 (18), pp. 457-503 : 470-472

Marshallora monteiroi ( Rolán & Fernández-Garcés, 2015) n. comb.

( Figs 7 ; 8 ; 20 I-J)

“ Triphora ” monteiroi Rolán & Fernández-Garcés, 2015: 47 , pl. 3.

Triphora portoricensis non Rolán & Redfern, 2008 – Lamy & Pointier 2018: 289, pl. 92, fig. 11.

TYPE MATERIAL. — Holotype. Guadeloupe • sh; Basse-Terre, Baie de Baille-Argent ; KARUBENTHOS 1 sta. GD21, 16°15’33”N, 61°48’48”W; depth 40 m; MNHN-IM-2000-30473 .

TYPE LOCALITY. — Guadeloupe: Basse-Terre, Baie de Baille-Argent; KARUBENTHOS 1 sta. GD21, 16°15’33”N, 61°48’48”W; 40 m.

MATERIAL EXAMINED. — Guadeloupe. KARUBENTHOS 1 • 1 sh [previously identified as Marshallora modesta – this shell is from the type locality]; sta. GD21; MNHN .

Martinique. MADIBENTHOS. ‘Nord Atlantique’ • 1 sh; sta. AD263; MNHN • 1 sh; sta. AD275; MNHN • 1 sh; sta. AB350; MNHN. — ‘Sud Atlantique’ • 1 sh; sta. AS252; MNHN. — ‘Nord Caraibe’ • 10 sh, 1 spm; sta. AD283; MNHN • 1 sh; sta. AD290; MNHN • 1 sh; sta. AS482; MNHN.

BATHYMETRIC DISTRIBUTION. — Recorded depth in Guadeloupe: 40 m (including a live specimen). Recorded depth in Martinique: 10-80 m (live specimen at 37-40 m).

GEOGRAPHIC DISTRIBUTION. — Guadeloupe and Martinique.

EMENDED DESCRIPTION

Shell sinistral, conical to slightly pupoid, rectilinear to slightly convex profile, up to 4.6 mm long, 1.2 mm wide, length/width ratio 2.4-3.9; adult shells reach at least 2.0 mm in length. Protoconch sub-columnar, slightly inflated, of 2.75-3.0 whorls, 0.44-0.51 mm long, 0.41-0.48 mm wide, weak distinction between protoconch and teleoconch; first smooth, globose, but on subsequent whorls axial ribs soon appearing, with their adapical part emerging on the abapical part of the smooth whorl above, assuming an irregular shape, often considerably sigmoid on second whorl, but usually slightly sigmoid or nearly orthocline (sometimes opisthocline) towards the end of protoconch, where it numbers 20-22 ribs; one main spiral cord emerging soon after the axial ribs, keel-shaped and often smooth (but wrinkled in some shells), situated at 47-60% of last whorl height. Teleoconch with up to nine whorls; two spiral cords (adapical and abapical) at the beginning, the abapical one continuous to that of protoconch; median spiral cord emerging at the beginning of second to the end of third whorl, reaching the same size than other cords after one to two whorls; at the body whorl, the three cords are equidistant and have nearly the same size; 22-24 nearly orthocline axial ribs on the sixth whorl; rounded nodules of medium size; distinct suture, with a sutural cord; slightly nodulose to smooth subperipheral cord, two smooth, well-developed basal cords; no supranumerical cords; aperture ovate (with a minute notch in the posterior end), 0.50-0.81 mm long, 0.40-0.61 mm wide, length/width ratio 1.3-1.5; anterior canal short, open, 0.13-0.25 mm long, 0.14-0.28 mm wide, length/width ratio 0.8-0.9. Protoconch brownish, cream, golden or white; teleoconch dark to light brown, rarely beige; head-foot white, translucent.

REMARKS

This species was previously known only from the holotype, which has a light brown teleoconch and white protoconch ( Rolán & Fernández-Garcés 2015). An additional shell from the type locality in Guadeloupe is illustrated ( Fig. 7J ), with a darker teleoconch, which is the common pattern in shells of Marshallora monteiroi n. comb. from Martinique ( Fig. 7 ). An exception is a shell with a gradual (not abrupt) color transition between the lighter protoconch and the cream/beige teleoconch ( Fig. 7K ), which is more similar to the planktotrophic species Marshallora ostenta Rolán & Fernández-Garcés, 2008 , and it perhaps does not belong to M. monteiroi n. comb. The color of the protoconch is variable among shells of M. monteiroi n. comb., from white to brownish ( Fig. 7 ). There are also slight variations in the protoconch sculpture, with a spiral cord usually smooth and situated at the mid portion of the whorl, but sometimes wrinkled or situated at a lower portion, in addition to the variable axial ribs ( Fig. 8 ). Remarkably, the adult shell length ranges from 2.0 to 4.6 mm.

This species is placed under the Atlantic genus Marshallora owing to the brown teleoconch, smooth basal cords ( Fig. 7 L-M), absence of supranumerical cords ( Fig. 7N ) and white head-foot ( Fig. 20 I-J), among other features. There are other Caribbean species with paucispiral protoconchs currently allocated under the catch-all taxon “ Triphora ” that, otherwise, fit into the concept of Marshallora , following the above-mentioned features [including the white head-foot of one species – Redfern (2013: fig. 356B)]. These species are herein transferred to Marshallora , pending future anatomical and genetic studies to test these allocations: Marshallora abacoensis (Rolán & Lee, 2008) n. comb., Marshallora armandoi (Espinosa & Ortea, 2020) n. comb., Marshallora calva ( Faber & Moolenbeek, 1991) [already cited in this genus by Fernandes & Pimenta 2020] and Marshallora grenadensis (Rolán & Lee, 2008) n. comb. The latter, only known from the holotype, is the most similar species to M. monteiroi n. comb., regarding slight differences in the color and sculpture of the protoconch ( Rolán & Fernández-Garcés 2015), and possibly having a less inflated protoconch and slightly later emergence of the median spiral cord (emerging narrowly at the end of fourth teleoconch whorl – Rolán & Fernández-Garcés 2008: fig.30D), requiring additional material for further comparisons.

Figures

FIG. 7. — Marshallora monteiroi (Rolán & Fernández-Garcés, 2015) n. comb.: A, L, MNHN, sta. AD283, 4.2 mm; B, MNHN, sta. AS482, 2.8 mm; C, MNHN, sta. AB350, 2.0 mm; D, MNHN, sta. AD275, 3.7 mm; E-H, N, MNHN, sta. AD283, 3.0 mm, 3.0 mm, 3.5 mm, 3.0 mm; I, MNHN, sta. AS252, 3.0 mm; J, MNHN, sta. GD21 (KARUBENTHOS 1), 4.6 mm; K, M, MNHN, sta. AD263, 2.7 mm. Scale bars: A-K, 1 mm; L-N, 200 μm.

FIG. 8. — Marshallora monteiroi (Rolán & Fernández-Garcés,2015) n. comb.: A, MNHN,sta. AD283 (Fig.7A); B, MNHN,sta.AS482 (Fig. 7B); C, MNHN,sta. B350 (Fig. 7C); D, MNHN, sta. AD275 (Fig. 7D); E, MNHN, sta. AD283 (Fig. 7E); F, MNHN, sta. AD283 (Fig. 7F); H, MNHN, sta. AS252 (Fig. 7I); H, MNHN, sta. AD263 (Fig. 7K). Scale bars: 100 μm.

FIG. 20. — Live triphorids from Martinique and Guadeloupe (marked with asterisk): A-D, Nototriphora decorata (C.B. Adams,1850),MNHN,sta. GR10 (A), AS253 (B), AB382 (C), AB161 (D); E, F, Sagenotriphora osclausum (Rolán & Fernández-Garcés, 1995), MNHN, sta. AB191; G, H, Triphora ellyae De Jong & Coomans, 1988, MNHN, sta. AB308; I, J, Marshallora monteiroi (Rolán & Fernández-Garcés, 2015) n. comb., MNHN, sta. AD283 (I), GD21 (J). Credits: MNHN team.