Edentellina caribbea, (Edmunds, 1963)

EdenTellina caribbea ( Edmunds, 1963)

( Figs 5G, H, 18–20)

Berthelinia caribbea Edmunds 1963: 731–737 View in CoL , figs 1–5, pl. 1. Type locality: Port Royal , Jamaica.

Type material

Berthelinia caribbea , holotype, complete specimen, not examined ( NHMUK 1962261 About NHMUK ), six paratypes ( NHMUK 1962262 About NHMUK , NHMUK 1962263 About NHMUK ) .

Additional material examined

Bermuda: Sandys Parish , Bermuda, 1 m depth, 18 June 2009, three specimens 2.5–3 mm long (shell), leg. Pola et al. ( CASIZ 181198–181200 ). St. George Island , Bermuda, 4 m depth, 10 June 2009, one specimen 2 mm long (live), leg. Pola et al. ( CASIZ 181097 ) .

Caribbean : Canal off Snake Creek , Plantation Creek, Florida, 14 July 1978, one specimen (dry) 4 mm long, leg. M. Miller ( CASIZ 112229 ) . Andros Island , Bahamas, 3 m depth, 28 August 1971, one valve 0.9 long, leg. D. R. Moore ( CASIZ 112231 ) . Sweeting Cay , Bahamas, tissueonly, isolateBcar10 Swe 01. Abaco, Bahamas, one specimen 4 mm long (shell), leg. C. Redfern ( NHMLA 011629 ) . Grande Caye , St. Martin, 4–6 m depth, 21 April 2012, one specimen 3 mm long (shell), leg. G. Paulay & F. Michonneau ( FMNH 451025 About FMNH ) . Petite Terre , Guadeloupe, 26 May 2012, one specimen 1 mm long (shell), isolate JC45, Karubenthos 2012 Expedition (stn. GB31) ( MNHN IM-2013-53075 ) . Lagon de Saint François , Guadeloupe, 28 May 2012, one specimen 3 mm long (shell), isolate JC46, Karubenthos 2012 Expedition (stn. GB35) ( MNHN IM-2013-53074 ) ; one specimen 2.5 mm long (shell), isolate JC44, Karubenthos 2012 Expedition (stn. GB35) ( MNHN IM-2013-53076 ) ; one specimen 2 mm long (shell), isolate JC43, Karubenthos 2012 Expedition (stn. GB35) ( MNHN IM-2013-53077 ) . Guayama Bay , Puerto Rico, 24 November 1964, three specimens 3–3.5 mm long (shells), leg. Warmke & Modovar ( CASIZ 074790 ) . La Parguera , Puerto Rico, 10 April 1965, two specimens (dry) 1.2–1.8 mm long, leg. P. Glynn ( CASIZ 201950 ) . Puerto Viejo , Limón, Costa Rica, 1–8 m depth, 30 October 1986, one valve 2.5 mm long, leg. R. C. Brusca & P. M. Delaney ( NHMLA 1986 - 202.28 ) . 1 km northeast of Punta Manzanillo , Limón, Costa Rica, 23 m depth, 13 March 2001, one specimen 4.8 mm long (shell), leg. S. Avila ( MZUC INB3321518 ) .

Brazil: Plage de Gaibu, Cabo de Santo Agostinho , Pernambuco , Brazil, 1985–89, seven valves 1.8–3.5 mm long, leg. P. Maestrati ( MHNH). Base of Mushroom Reef, 3 km southeast of Santa Barbara Island, Abrolhos Archipelago , Brazil, 23 m depth, 27 July 1977, seven valves and fragments, 1–3 mm long, leg. E. Petuch ( CASIZ 112230 ) .

Description

Body elongate, ≤ 6.5 mm in length, completely retractable inside of shell. Body colour bright green, with numerous minute white speckles throughout, but more densely arranged on the dorsal side of head ( Fig. 5G, H). Head elongate, with eye spots located on dorsal swelling near centre, surrounded by white pigment; two parallel brown lines run between base of rhinophores and eye spots, then merge into single brown line running backwards to pericardium; brown spots scatered over rest of head in some specimens. Rhinophores enrolled, green, with high concentration of small white and brown speckles. Oral tentacles short, green, with white speckles at base. Foot lighter than rest of animal. Mantle visible through shell, dark green, covered with large, irregular whitish-beige patches, variable in size, and numerous transverse white and brown lines; edge surrounded by alternating opaque white patches composed of densely arranged speckles and dark brown patches. Foot not extending to posterior end of shell, forming small triangular projection.

Shell up to 4.8 mm × 3.5 mm in size, tallest point near anterior margin, widest point near ventral margin; shell shape ovoid, dorsal margin regularly curved with distinct apex, ventral margin more flatened; anterior margin convex, irregularly curved, slightly more flatened dorsally, posterior margin shorter, narrowing gradually ( Fig. 18G, H). Protoconch on lef valve of teleoconch, ~110 µm long, with 1.5 whorls ( Fig. 18K). Hinge on dorsal margin of shell, formed by flatened, corrugated, nearly straight area, margin on both valves; large, rounded condyloid tooth at posterior end of hinge on right valve, triangular, fossete-like hinge socket on lef valve, at posterior end of hinge ( Fig. 18I, J). Shell translucent, with no visible markings or spots on shell surface, sof parts of body visible through it ( Fig. 18A–D).

Adductor muscle in line with highest and widest points of shell ( Fig. 19A), connected to narrow and elongate head retractor muscle. Adductor scar visible on shell ( Fig. 18H). Gill large, occupying almost height of body, posterior to adductor muscle, covering anterior portion of digestive gland. Anterior half of body in preserved specimens with pair of elongate pharyngeal appendages visible above adductor muscle ( Fig. 19B), connecting to the pharyngeal bulb posteriorly ( Fig. 19C). Penis elongate; distal end pointed, with no stylet visible; proximal end wider, with strong retractor muscle and long, tubular deferent duct ( Fig. 19D).

Radula with 25 teeth in descending limb and 11 fully formed teeth + 1 ghost tooth in ascending limb, in 3-mm-long specimen from Abaco, Bahamas ( NHMLA 011629) ( Fig. 20A). Active tooth ~110 μm long ( Fig. 20B), with sharp, harpoontip shaped, pointed tip; blade elongate, with central row of numerous short, delicate denticles ( Fig. 20D); base short, curved. Ascus containing three disorganized elongate pre-radular teeth ( Fig. 20C).

Biology

According to Grahame (1969), E. caribbea feeds on Caulerpa verticillata J. Agardh, 1847. Individuals have a short life span, with rapid growth rate and high fecundity ( Grahame 1969). Te number of eggs per egg mass varies from 14–32 ( Davis 1967) to 35–40, occasionally 80–100 ( Grahame 1969). Eggs were ~100 µm in diameter ( Clark and Jensen 1981), encased in ovoid capsules ~300 µm, developing into lecithotrophic larvae with a shell width of 230 µm ( Grahame 1969); newly hatched veligers setle almost immediately on Caulerpa and begin to feed.

Range

Western Atlantic Ocean: Bermuda (present paper), Florida Keys ( Moore and Miller 1979, Clark 1994; present paper), Bahamas ( Valdés et al. 2006, Redfern 2001, 2013; present paper), Cuba ( Espinosa et al. 2006), Puerto Rico ( Warmke 1966, Grahame 1969; present paper), Jamaica ( Edmunds 1962, 1963), St. Martin (present paper), Guadeloupe ( Ortea et al. 2012; present paper), Mexico ( Ortigosa et al. 2013, 2015), Belize ( Clark and DeFreese 1987), Costa Rica ( Espinosa and Ortea 2001, Camacho-García et al. 2014; present paper), Panama ( Meeder and Moore 1972), and Brazil ( Meeder and Moore 1972, Mello and Perrier 1986; present paper).

Remarks

Edmunds (1963) described Berthelinia caribbea Edmunds, 1963 based on live animals collected in Jamaica. Te most distinctive external characteristic of this species is the presence of irregular horizontal bands of dark reddish-brown or yellowish-brown on the mantle, showing clearly through the transparent shell in both live and preserved specimens.

Redfern (2013: 280, fig. 780A–C) described and illustrated a second species of Berthellinia from the Bahamas, based on shells with a slightly different shell morphology and a more coiled protoconch than those of B. caribbea , which he also illustrated. Tese animals might constitute a distinct species, but in the absence of material for anatomical and molecular work, it cannot be described.

For this paper, we examined and sequenced several specimens from the Caribbean region and Brazil matching the original description of B. caribbea . Geometric morphometrics analyses confirmed the shells of these specimens are morphologically similar to those of other species of Edentellina . Additionally, molecular data confirm that B. caribbea is sister to the rest of Edentellina . Based on those two lines of evidence, we transfer B. caribbea to Edentellina and confirm that E. caribbea is a valid species name.

Te ABGD species delimitation analyses based on 16S split E. caribbea into two different groups, but this split was not recovered in the COI and H3 analyses. Moreover, there are no obvious morphological differences between these two groups, thus they are here maintained in the same species. Te two groups recovered have different geographical ranges, one including Bahamian specimens and the other Caribbean-proper specimens, suggesting a certain degree of genetic isolation between the two populations. Further research including a larger sample size might yet support cryptic diversity in E. caribbea .