Supplanaxis nancyae (Petuch, 2013) Strong & Bouchet, 2020

Strong, Ellen E. & Bouchet, Philippe, 2020, Hidden in plain sight: two co-occurring cryptic species of Supplanaxis in the Caribbean (Cerithioidea, Planaxidae), ZooKeys 991, pp. 85-109 : 85

Supplanaxis nancyae (Petuch, 2013) comb. nov. Figs 3C , 4H-O , 6 , 7A-L at left

Planaxis (Supplanaxis) nancyae Petuch, 2013: 193, fig. 6.13A, B

Holotype.

HAITI • 11 mm in height; off southern Gonave Island; depth 2 m; under rocks; FMNH 328402 (Fig. 3C )

Other material.

ANGUILLA • 6 spms; 29 Apr. 1958; Smithsonian - Bredin Caribbean Expedition; USNM 738885?

ANTIGUA AND BARBUDA • 9 spms; Antigua, Shell Beach; CI Aslaksan leg.; USNM 608782; • 2 spms; Antigua, Nonsuch Bay, N side of Bird Island; depth 4 ft; 24 Apr. 1958; Smithsonian - Bredin Caribbean Expedition; R/V Freelance; shore coll.; USNM 683510; • 21 spms; Redonda Island, lee side; 10 Apr. 1956; Smithsonian - Bredin Caribbean Expedition; R/V Freelance; W Schmitt leg.; wave washed rocks; USNM 714035; • 67 spms; Antigua, Green Island; [17°04'12"N, 61°40'08"W]; 24 Apr. 1958; Smithsonian - Bredin Caribbean Expedition; R/V Freelance; J Clarke leg.; USNM 1620283 (ex USNM 738725).

BAHAMAS • 5 spms; Rawson leg.; USNM 1620260 (ex USNM 54705); • 2 spms; New Providence, The Caves; [25°04'10"N, 77°27'02"W]; H Dodge leg.; USNM 1620274 (ex USNM 603895).

BARBADOS • 1 spm; USNM 19768; • 1 spm; EW Williams, CB Lungren leg.; USNM 341803; • 4 spms; beach; USNM 459982; • 32 spms; off Needham Pt.; low tide; USNM 459983; • 1 spm; Hastings Rocks; 13°04'25"N, 59°35'39"W; Nov. 2018; P Bouchet leg.; GenBank: MT921879, MT921911; MNHN-IM-2019-1729; • 1 spm; ibid; GenBank: MT921880, MT921912; MNHN-IM-2019-1707; • 1 spm; ibid; GenBank: MT921881, MT921913; MNHN-IM-2019-1708; • 1 spm; ibid; GenBank: MT921882, MT921914; MNHN-IM-2019-1709; • 1 spm; ibid; GenBank: MT921883, MT921915; MNHN-IM-2019-1710; • 1 spm; ibid; GenBank: MT921884, MT921916; MNHN-IM-2019-1711; • 1 spm; ibid; GenBank: MT921885, MT921917; MNHN-IM-2019-1712; • 1 spm; ibid; GenBank: MT921886, MT921918; MNHN-IM-2019-1713; • 1 spm; ibid; GenBank: MT921887, MT921919; MNHN-IM-2019-1714.

BELIZE • 4 spms; Carrie Bow Cay, NE Cay, Glover’s Reef; 15 Aug. 1973; CCRE - Caribbean Coral Reef Ecosystems, Belize; RS Houbrick leg.; intertidal on rocks; USNM 1620286 (ex USNM 771083).

BRITISH VIRGIN ISLANDS • 5 spms; Tortola; Kjaer leg.; USNM 6488; • 4 spms; Jost Van Dyke Island, Little Harbour; Apr. 1958; Smithsonian - Bredin Caribbean Expedition; R/V Freelance; shore coll.; USNM 683404.

COLOMBIA • 4 spms; New Grenada, Sabanilla; USNM 103165; • 11 spms; “Albatross”, Sabanilla; USNM 193614; • 7 spms; New Grenada, Sabanilla; USNM 224969.

CURAÇAO • 5 spms; Slangenbaai; 1 Dec. 1971; KB Meyer leg.; on rocks just above tide; USNM 702302; • 1 spm; Willemstad; 23 Jun. 1925; J Eldred leg.; tide pools just above high tide; USNM 889594; • 1 spm; Willemstad; 23 Jun. 1925; J Eldred leg.; tide pools just above high tide; USNM 889598; • 1 spm; S shore, beach in front of CARMABI research station; 12°07'20"N, 68°58'08"W; 18 May 2015; E Strong leg.; among cobbles; GenBank: MT921875, MT921907; USNM 1618949; • 1 spm; ibid; GenBank: MT921876, MT921908; USNM 1618950; • 1 spm; ibid; GenBank: MT921877, MT921909; USNM 1618951; • 1 spm; ibid; GenBank: MT921878, MT921910; USNM 1618952.

DOMINICA • 11 spms; Marigot; RG Fennah leg.; USNM 513253; • 3 spms; Scotts Head, windward coast; 27 Feb. 1966; Manning and Hobbs leg.; among rocks above or at high tide level; USNM 678753; • 1 spm; Prince Rupert Bayat Cabrits; 9 Mar. 1966; Hobbs and Manning leg.; rocky; USNM 678763; • 1 spm; W of Portsmouth; 19 Apr. 1939; Smithsonian - Bredin Caribbean Expedition; Nicholson, et al leg.; among boulders and off shingle beach; USNM 682469; • 81 spms; Berekua; 8 Feb. 1965; Smithsonian - Bredin Caribbean Expedition; WW Wirth leg.; on rocks on beach; USNM 709072.

DOMINICAN REPUBLIC • 1 spm; Oro Oro Beach [sic, possibly Playa Dorada], S. shore; [19°46'27"N, 70°38'30"W]; H Dodge leg.; USNM 1620275 (ex USNM 603900).

GRENADA • 5 spms; Saline Point; 14 Mar. 1956; Smithsonian - Bredin Caribbean Expedition; R/V Freelance; W Schmitt and F Chace leg.; USNM 714033.

GUADELOUPE • 46 spms; Aug. 1946; on rocks; USNM 1620270 (ex USNM 487939); • 1 spm; Plage de Malendure; 16°10'28"N, 61°46'47"W; 7 May 2012; KARUBENTHOS Expedition stn. GM7; GenBank: MT921870, MT921902; MNHN-IM-2009-26684; • 1 spm; Plage de Malendure; 16°10'28"N, 61°46'47"W; 1 Apr. 2017; D Lamy leg.; GenBank: MT921871, MT921903; MNHN-IM-2019-1703; • 1 spm; ibid; GenBank: MT921872, MT921904; MNHN-IM-2019-1704; • 1 spm; ibid; GenBank: MT921873, MT921905; MNHN-IM-2019-1705; • 1 spm; ibid; GenBank: MT921874, MT921906; MNHN-IM-2019-1706.

HAITI • 3 spms; Orcutt leg.; USNM 1620262 (ex USNM 383065); • 166 spms; Département de l’Ouest, Saltron; Orcutt leg.; USNM 1620267 (ex USNM 439970); • 6 spms; Département du Sud, Port-Salut; Orcutt leg.; USNM 1620268 (ex USNM 440004).

HONDURAS • 34 spms; Utilla Island; [16°05'47"N, 86°55'44"W]; Simpson leg.; USNM 1620264 (ex USNM 434879); • 1 spm; Webb leg.; USNM 1620266 (ex USNM 434885).

JAMAICA • 1 spm; St. Mary, Markham Hill; Orcutt leg.; USNM 377918; • 1 spm; Pt. Antonio; CWJ leg.; USNM 1620265 (ex USNM 434882); • 4 spms; Portland, near Buff Bay; Orcutt leg.; USNM 1620269 (ex USNM 441213); • 1 spm; Portland, Port Antonio; Vendeyes, Orcutt leg.; USNM 1620271 (ex USNM 518050); • 8 spms; St. Mary, 2 mi. N Port Maria; 18°24'19"N, 76°53'18"W; JI McCurkin leg.; 1 ft above splash line under cobbles; USNM 1620285 (ex USNM 770590).

MEXICO • 2 spms; Quintana Roo, Mujeres Island, Naval Station; 29 Mar. 1960; Smithsonian - Bredin Caribbean Expedition; R/V Blue Goose; W Schmitt leg.; USNM 662200; • 2 spms; Cozumel, 1 mi. N of San Miguel, in front of Cabanas del Caribe property; [20°31'59"N, 86°56'21"W]; 3 Apr. 1960; Smithsonian - Bredin Caribbean Expedition; R/V Blue Goose; H Rehder, W Schmitt and E Bousfield leg.; on rocks from above high tide to below water line; USNM 1620276 (ex USNM 662773); • 1 spm; Quintana Roo, Cozumel Island; 9 Apr. 1960; Smithsonian - Bredin Caribbean Expedition; R/V Blue Goose; H Rehder and E Bousfield leg.; splash pool high up; USNM 735218; • 1 spm; Quintana Roo, Ascension Bay, Suliman Pt. to 300 yds. to SW shore; 19 Apr. 1960; Smithsonian - Bredin Caribbean Expedition; R/V Blue Goose; W Schmitt, F Daiber, E Bousfield, J Clarke, H Rehder, Haynes and Harvey leg.; reef to sand flats; USNM 736379.

MONTSERRAT • 24 spms; Fox Bay, just N of Plymouth; 20 Apr. 1959; Smithsonian - Bredin Caribbean Expedition; R/V Caribee; black sand beach; USNM 1620281 (ex USNM 682493).

NETHERLANDS ANTILLES • 12 spms; St. Martin; Ford leg.; USNM 1620263 (ex USNM 434878).

PANAMA • 1 spm; San Blas; TG Thompson leg.; USNM 1620273 (ex USNM 597416); • 3 spms; Puerto Perme, NW of Cape Tiburon; [8°44'13"N, 77°32'41"W]; 14 Mar. 1953; RH Stewart leg.; USNM 1620279 (ex USNM 664216).

PUERTO RICO • 1 spm; Culebra, Ensenada Honda; USNM 161343; • 15 spms; E of Guanica, Tamarindo Beach; 23 Feb. 1958; GL Warmke leg.; under rocks; USNM 655599; • 2 spms; Fajardo; 10 Dec. 1951; J Weber leg.; USNM 1620277 (ex USNM 663091).

ST. LUCIA • 3 spms; Pigeon Island, N of Pigeon Island Club; 15 Apr. 1959; Smithsonian - Bredin Caribbean Expedition; R/V Caribee; sand and boulder flats around breakwater; USNM 682400.

ST. VINCENT AND THE GRENADINES • 9 spms; St. Vincent; Chamberlain leg.; USNM 1620261 (ex USNM 131804).

U.S. VIRGIN ISLANDS • 3 spms; St. Thomas; CB Adams leg.; USNM 1620259 (ex USNM 6419); • 1 spm; St. Croix; Helen F Dunn leg.; USNM 363994; • 9 spms; St. Croix, Davies Bay; Jan. 1936; HA Beatty leg.; from rocks; USNM 423961; • 12 spms; St. Thomas; Petit leg.; USNM 1620272 (ex USNM 530351); • 2 spms; St. Thomas, S end Magens Bay; M Jones leg.; rocks adjacent to beach; USNM 1620280 (ex USNM 666148); • 4 spms; St. John, Caneel Bay; [18°20'34"N, 64°47'13"W]; 25 Mar. 1958; Smithsonian - Bredin Caribbean Expedition; R/V Freelance; C Shuster and J Finlay leg.; USNM 1620284 (ex USNM 738775).

UNITED STATES • 2 spms; Miami Beach, South Beach, at jetty; [25°45'48"N, 80°07'45"W]; 12 Aug. 84; RS Houbrick leg.; intertidal rock and boulders; USNM 1620287 (ex USNM 842270); • 5 spms; Miami Beach, South Beach, at jetty; [25°45'48"N, 80°07'45"W]; 20 Nov. 83; RS Houbrick leg.; intertidal, on rocks and boulders; USNM 1620288 (ex USNM 842272); • 2 spms; South Miami Beach; 16 Jan. 1984; RS Houbrick leg.; USNM 1620289 (ex USNM 858456).

VENEZUELA • 5 spms; Cubagua Island; WL Schmidt leg.; low cliffs just back of sand beach; USNM 604065; • 1 spm; La Orchila Island; Sep. 1950; S Arias-Carbonell leg.; USNM 656012.

Description

. Shell. Shell (Figs 3C , 4H-O , 7A-L at left) medium-sized for the genus, solid, littoriniform, high-spired, consisting of 5+ (apex generally broken or corroded in adults) weakly convex whorls separated by impressed suture, last whorl occupying ca 75-80% of total shell height. Shell surface rarely smooth, usually covered with 15-17 even, incised spiral grooves extending over all shell height, especially well marked on base. Aperture ovoid, occupying ca 50% of total shell height, with or without sharp internal lirae, 7-11 in number, outer lip regularly convex, columellar pillar truncated above broad siphonal notch, callus adpressed to parietal and columellar areas, particularly expanded adapically, its outer edge thickened and slightly raised, parietal tooth strong, blunt. Color uniformly reddish brown to dark violet, parietal tooth and columellar callus often lighter. Height 11-13.5 mm.

Radula . Radula taenioglossate (Fig. 6A ). Rachidian pentagonal, with broad basal plate, long basolateral extensions, and short, rounded, median basal projection (Fig. 6B, D ). Upper lateral part of basal plate with robust, rounded basal denticle. Rachidian cutting edge rather narrow, comprising one-half width of tooth, but thick and heavily buttressed. Cutting edge sharply concave at midline, with narrowly rectangular, pointed median cusp, flanked by two to four smaller, robust, pointed denticles on each side. Lateral tooth with broad, high basal plate with central supporting ridge, rounded margins, and long lateral basal extension (Fig. 6C ). Cutting edge broad with large, squarish, central cusp flanked by three to four inner and two to three sharp outer denticles. Marginal teeth elongate with curved paw-like tips (Fig. 6A, F ). Inner marginal tooth with narrow flange along length of shaft outer edge, and with concave, rake-like tip with nine to ten rounded denticles. Outer marginal tooth with broad, membranous flange along distal outer edge, and with broad, bilobed tip bearing approximately 32 to 34 small, rounded denticles.

Distribution and ecology.

The range of Supplanaxis nancyae extends from Miami Beach, Florida, in the north, to the northern coast of South America, from Veracruz, Mexico in the west ( Tunnell 1974) and as far east as Trinidad and Tobago off Venezuela, including the Gulf of Mexico, Caribbean Sea and the Antillean Arc (Fig. 7 ). This species can occur in syntopy with Supplanaxis nucleus (Fig. 8 ) and museum lots across its range may comprise mixtures of the two species; ~ 30% of museum lots in the USNM with more than a single specimen included both species. Guadeloupe specimens of the two species are illustrated by Lamy and Pointier (2017: pl. 40, fig. 6A, B [ nucleus ], 6C-E [ nancyae ], both as S. nucleus ). It is unknown whether this species also occurs in Bermuda.

Remarks.

Petit (2013: 9) questioned the precision of the type locality and presented circumstantial evidence that Petuch’s original material consisted of shells occupied by hermit crabs.

Planaxis nancyae was described based on two specimens, both unusually smooth and reddish for the species. In the absence of sequenced topotypic material, we are confident of the identity of the holotype based on our examination of more than 2,100 specimens of Supplanaxis from all over the Caribbean, and particularly material from Jamaica and the Virgin Islands that conforms with both our sequenced material from the Lesser Antilles and the Haiti holotype. The shell of S. nancyae differs from that of S. nucleus in its generally smaller size and lighter color, the regularly convex shape of the aperture, and its adapically expanded callus.

The protoconch figured by Houbrick (1987: fig. 17H) for S. nucleus may be that of S. nancyae , as all the adult shells in that lot (USNM 714035) represent the latter species. The radula of S. nancyae was described and figured as S. nucleus by Bandel (1984: fig. 59; pl. 2 figs 6, 8), as is evident from the morphology of the rachidian. Indeed, Bandel (1984) mistook the comparatively short lateral extensions of the rachidian described by Troschel (1858) as erroneous, but the latter were based on S. nucleus which has a broader cutting edge and comparatively shorter lateral extensions. The radular morphology of S. nancyae differs from that of S. nucleus primarily in its narrower and thicker cutting edge of the rachidian, the robustness and shape of the rachidian basal denticle, the narrower and more pointed rachidian central cusp, and the slightly greater number of denticles on the outer marginal tooth. There may be fewer flanking denticles on the rachidian in S. nancyae caused by fusion of the innermost denticles with the central cusp, as seen in the specimens examined herein from Guadeloupe (Fig. 6B, D ), but the range of variation overlaps in the two species. These differences in tooth morphology strongly suggest the two species differ in trophic ecology, but this deserves further research. Regardless, in addition to features of the aperture of the shell, the characteristic rachidian provides diagnostic characters sufficient to separate S. nancyae from its co-occurring congener.

We note a strong resemblance with the fossil Planaxis ame Woodring, 1928 (342, pl. 25, fig. 16), known from the Upper Pliocene of Jamaica (type locality) and from the Upper Miocene Cercado Formation of the Dominican Republic (Landau, pers. comm.). Woodring compared Planaxis ame with P. nucleus , then the only known Recent Caribbean planaxid species, but the smooth forms of Supplanaxis nancyae are a better match, and we do not rule out that P. ame might turn out to be a senior synonym of S. nancyae .

Figures

Figure 3. Type specimens of Supplanaxis nucleus and relevant planaxids. A Buccinum nucleus Bruguiere, 1789. Neotype, MNHN-IM- 2000 - 35804 B Planaxis planicostatus G. B. Sowerby I, 1825. Syntype NHMUK 1966623 (© The Trustees of the Natural History Museum, London, http: // creativecommons. org / licenses / by / 4.0 /; https: // data. nhm. ac. uk / object / 4767541 c-a 5 d 1 - 41 db-aa 0 c- 0 c 03724 e 970 a) C Planaxis (Supplanaxis) nancyae Petuch, 2013. Holotype, FMNH 328402 (© Field Museum of Natural History-CC BY-NC; https: // collections-zoology. fieldmuseum. org / catalogue / 2877223) D Planaxis niger Quoy and Gaimard, 1833. Syntype, one of 22 specimens, MNHN-IM- 2000 - 27769 E Planaxis nucleola Moerch, 1876. Probable holotype, ZMK 152749. Scale bar: 1 cm.

Figure 4. Shell morphology of Supplanaxis from the Caribbean. Sequenced vouchers A-G S. nucleus H-O S. nancyae A-C Guadeloupe, Plage de Malendure A MNHN-IM- 2019 - 1716 B MNHN-IM- 2009 - 26686 C MNHN-IM- 2009 - 26687 D-E Barbados, Hastings Rocks. D Neotype, MNHN-IM- 2000 - 35804 E MNHN-IM- 2019 - 1728 F-G Curacao, S shore, beach in front of CARMABI research station F USNM 1618956 G USNM 1618953 H-J Guadeloupe, Plage de Malendure H MNHN-IM- 2019 - 1703 I MNHN-IM- 2019 - 1704 J IM MNHN- 2009 - 26684 K-L Barbados, Hastings Rocks K MNHN-IM- 2019 - 1729 L MNHN-IM- 2019 - 1711 M-O Curacao, S shore, beach in front of CARMABI research station M USNM 1618949 N USNM 1618951 O USNM 1618952. Scale bar: 1 cm.

Figure 6. Radular morphology of Supplanaxis nancyae (MNHN-IM- 2019 - 1703, except as noted) A Radular ribbon B Rachidian and lateral teeth C Detail of lateral teeth D Detail of rachidian. Note fusion of innermost denticle with central cusp E Rachidian and lateral teeth viewed at a ~ 45 ° angle from above, showing detail of cutting edge F Internal and external lateral teeth (MNHN-IM- 2019 - 1704). Scale bars: 200 µm (A), 50 µm (B, C, D, E, F).

Figure 7. Comparative shell morphology of Supplanaxis around the Caribbean. Supplanaxis nancyae is shown at left, and S. nucleus is at right, for each pair. The individuals from each pair were sampled from the same site and were originally part of the same lot A Florida, Miami Beach, South Beach, at jetty (at left, USNM 1620287; at right, USNM 842270) B Bahamas, New Providence, The Caves (at left, USNM 1620274; at right, USNM 603895) C Mexico, Cozumel, 1 mi. N of San Miguel (at left, USNM 1620276; at right, USNM 662773) D Jamaica, St. Mary, 2 mi. N Port Maria (at left, USNM 1620285; at right, USNM 770590) E Dominican Republic, Oro Oro Beach [sic, possibly Playa Dorada], S. shore (at left, USNM 1620275; at right, USNM 603900) F Virgin Islands, St. John, Caneel Bay (at left, USNM 1620284; at right, USNM 738775) G Antigua and Barbuda, Antigua, Green Id. (at left, USNM 1620283; at right, USNM 738725) H Honduras, Utilla Id. (at left, USNM 1620264; at right, USNM 434879) I Panama, Puerto Perme, NW of Cape Tiburon (at left, USNM 1620279; at right, USNM 664216) J Curacao, S shore, beach in front of CARMABI research station (at left, USNM 1618952; at right USNM 1618956; sequenced vouchers) K Guadeloupe, Plage de Malendure (at left, MNHN-IM- 2019 - 1703; at right MNHN-IM- 2009 - 26687; sequenced vouchers) L Barbados, Hastings Rocks (at left, MNHN-IM- 2019 - 1729; at right, neotype, MNHN-IM- 2000 - 35804; sequenced vouchers). Base map: Wikimedia Commons contributors (2017).

Figure 8. Habitat A Curacao, S shore, beach in front of CARMABI research station B Supplanaxis nucleus and S. nancyae individuals among cobbles.