Fenimorea culexensis Usticke, 1969

Fallon, Phillip J., 2016, Taxonomic review of tropical western Atlantic shallow water Drilliidae (Mollusca: Gastropoda: Conoidea) including descriptions of 100 new species, Zootaxa 4090 (1), pp. 1-363: 158-160

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http://doi.org/10.11646/zootaxa.4090.1.1

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scientific name

Fenimorea culexensis Usticke, 1969
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Fenimorea culexensis Usticke, 1969 

( Plate 74View PLATE 74)

Fenimorea culexensis Usticke, 1969: 28  , fig. 1124. Nowell-Usticke (1971: 23, pl. 4, fig. 1124); Maes (1983: 318, figs. 9, 20); Faber (1988: 78, 96); Boyko & Cordeiro (2001: 67); Williams (2005; 2009: species 1562).

Type material. The specimen in AMNH 195462 was invalidly designated the holotype by Nowell-Usticke in 1971, after the date of the publication of the original description in 1969. Because of this later designation, Boyko & Cordeiro (2001: 67) erroneously state that the designation of a holotype was actually a lectotype designation. However, the inference of a lectotype from a holotype designation is invalid (ICZN 2000 Article 74.5). The existence of at least one other type is inferred from the range in lengths and localities given by Nowell-Usticke in his original description, but the whereabouts of other types is unknown. The specimen in AMNH 195462 (12.0 x 6.0 mm), which matches the size of the one Nowell-Usticke intended as the type, and the original description, is here declared the lectotype.

Type locality. Virgin Gorda, British Virgin Is. The type locality was amended from just " Virgin Gorda " to the more specific locality, “The Baths”, by Nowell-Usticke (1971: 23). "The Baths" is written on the lectotype’s label.

Other material examined. An additional 42 specimens were examined: 23 spec. (11 measured): 13.3 x 5.7, 12.6 x 5.3, 11.5 x 4.9, 11.3 x 5.0, 10.5 x 4.5, 10.2 x 4.5, 10.0 x 4.0, 14.0 x 5.9, 9.0 x 4.4, 8.7 x 4.5 & 7.2 x 3.8 mm, in 3–4 m, on sand-drifted rocks, Muskmelon Bay, Guana I., Br. Virgin Is., 18 ° 29 ′06″N, 064° 34 ′ 40 ″W, V. O. Maes! Feb 1976 – 78 (ANSP 355001); 1 spec., 12.0 x 5.3 mm, Virgin Gorda, Br. Virgin Is., G. Dewey! (MCZ 294069); 1 spec. 16.5 x 6.7 mm, in 12 m, Tourmaline Reef, Puerto Rico, G. Mackintosh!, 12 Mar 1993 (author’s coll.); 2 spec., 15.4 x 6.4 & 14.0 x 6.0 mm, in 12 m, Tourmaline Reef, Puerto Rico, G. Mackintosh!, 12 Mar 1993 (USNM 900212); 14 spec., 4 measured: 14.1 x 5.7, 12.7 x 5.5 12.8 x 5.4 & 11.6 x 5.2 mm, in 1.5–2 m, W side of Icacos Cay, off Fajardo Puerto Rico, F. St. Clair! 5 Aug 1962 (UF 163020); 1 spec., 11.1 x 5.2 mm, in 4.6–6 m, Icacos Cay, off Fajardo Puerto Rico, C. J. Finlay!, Apr 1976, ex H.G. Lee coll. (UF 470300).

Range and habitat. British Virgin Is. ( Virgin Gorda; Guana I.), and Puerto Rico (Tourmaline Reef, off Mayaguez, W coast; Icacos Cay, off NE coast). Reported live from 1.5–12 m depths on fine sand.

Description. Shell small (to 16.5 mm), stoutly fusiform with a truncated anterior; whorls to about 8 ½, profile flat in sulcus, slightly convex on anterior ½, last whorl somewhat squarish, 68 % of total length. Surface smooth; axial ribs the predominant sculptural element. Protoconch lip could not be found on examined specimens; estimate approximately 2 smooth whorls Axial sculpture of low, weak, very irregular ribs, 12–16 on penultimate, 8–11 on last whorl to varix, ribs irregular in width, curved in sulcus, somewhat nodulose on whorl periphery, evanesce rapidly below whorl periphery. Ribs may coalesce or split, be narrow or wide on whorl shoulders. Growth striae present, develop into fimbriations at the whorl’s suture in some populations. Varix broad, hump-like, about ⅓-turn from edge of outer lip. Spiral sculpture of very fine spiral threads intersected and made jagged by subequal growth striae (the shell surface microsculpture). 6–7 widely spaced shallow spiral grooves from whorl periphery to shell base that override microsculpture. Sulcus flat, angled from whorl periphery to suture, demarcated by an abrupt change in rib strength at the sulcus. Ribs broader, more irregular in shape than at periphery. Outer Lip flattened to lip’s edge; slight bumps at the terminus of the spiral grooves on edge of lip appear like they were formed by pinching the lip at these points. Edge of lip forms a low arc from anal sinus to end of anterior canal; stromboid notch absent. Anal sinus a deep U-shaped notch, slightly constricted by parietal lobe and upward turn of outer lip. Inner lip narrow, thick and erect anteriorly, thin and recumbent on parietal wall, formed into a lobe posteriorly. Anterior canal very short, open, notched; anterior fasciole not swollen, surface with spiral threads, closer and larger than on shell base. Color creamy white with brownish-yellow penciled lines between ribs and similar penciled lines in spiral grooves; irregularly placed patches appear on whorl shoulders, and a large patch on varix; ribs in sulcus white.

Remarks. Taxonomy. Fenimorea culexensis  is recognizable as belonging in Fenimorea  : microsculpture typical for the genus, a short anterior canal, a broad hump-like varix, and ribs to the suture but strongly modified in the sulcus. It is unique in its color pattern of dark radial streaks between ribs and spiral lines that form a striking checkerboard pattern on the last whorl. Its highly irregular ribs are also unique. Variability. Average total length of 21 measured specimens is 11.93 (7.2–16.5 mm), their average W/ L ratio  is 0.443. Small differences are seen in the pattern of markings among populations. Specimens examined from Guana I. have a more distinct checkerboard pattern on the last whorl than those from the two Puerto Rican localities. Specimens from Tourmaline Reef, Mayaguez, have more white on whorl shoulders. Identification. Fenimorea culexensis  may appear similar in color and form to small F. fucata (Reeve, 1845)  from the same region ( U.S. and Br. Virgin Is.) but F. fucata  , along with other differences, lacks the checkerboard pattern of brownish-yellow spirals and axial stripes on the last whorl, and has more pronounced teeth on the outer lip in mature individuals. Fenimorea culexensis  resembles other small F. fucata  -like species: F. caysalensis  , new species, F. jongreenlawi  , new species, and F. f a ba e, new species. From F. caysalensis  it differs in possessing a more angular shoulder, a squarish last whorl, and different coloration. These same differences apply to F. jongreenlawi  and F. f a ba e. In addition to these difference, F. culexensis  possesses small bumps on the edge of the lip at the terminus of spiral grooves, both grooves and bumps are absent in F. jongreenlawi  and F. fabae  .