Mothocya bertlucy, Hadfield, Kerry A., Sikkel, Paul C. & Smit, Nico J., 2014

Hadfield, Kerry A., Sikkel, Paul C. & Smit, Nico J., 2014, New records of fish parasitic isopods of the gill-attaching genus Mothocya Costa, in Hope, 1851 from the Virgin Islands, Caribbean, with description of a new species, ZooKeys 439, pp. 109-125 : 111-117

Taxon classification Animalia Isopoda Cymothoidae

Mothocya bertlucy sp. n. Figs 3-7

Material examined.

All material from the gills of the redlip blenny, Ophioblennius macclurei .

Holotype. Ovigerous ♀ (8.0 mm TL; 4.5 mm W), collected from Lameshur Bay, 18°18'59"N, 64°43'25"W, St. John Island, US Virgin Islands, July 2013, coll. L. Renoux & J. Sellers (AMNH_IZC 00197449).

Paratypes. ♀ dissected (7.0 mm TL; 3.5 mm W), three immature ♂♂, one dissected (5.5-6.0 mm TL; 2.0-2.5 mm W), collected from Brewers Bay, 18°20'24"N, 64°58'44"W, St. Thomas Island, Caribbean Sea), 19 May 2013, coll. J. A. Barry & A. McCammon (AMNH_IZC 00197450). Ovigerous ♀ (9.0 mm TL; 5.0 mm W), collected from Lameshur Bay, 18°18'59"N, 64°43'25"W, St. John Island, US Virgin Islands, July 2013, coll, L. Renoux & J. Sellers (AMNH_IZC 00197451). Ovigerous ♀ (7.5 mm TL; 4.0 mm W), mature ♂ (6.0 mm TL; 4.0 mm W), collected from Guana Island, 18°28'0"N, 64°33'59"W, British Virgin Islands, 07 July 2013, coll: R. Ditter & J. Barry (AMNH_IZC 00197452).

Ovigerous female holotype.

Body oval and moderately twisted, 1.9 times as long as greatest width, widest at pereonite 3, most narrow at pereonite 1, lateral margins slightly convex. Cephalon 0.7 times longer than wide, visible from dorsal view. Eyes oval with distinct margins, 0.2 times width of cephalon, 0.4 times length of cephalon. Pereonite 1 smooth, anterolateral angle rounded. Posterior margins of pereonites smooth and slightly curved laterally. Coxae narrow with rounded point, shorter or same length as pereonite. Pereonites 1-3 increasing in length and width; 4-7 decreasing in length and width, becoming progressively rounded posteriorly. Pleon with pleonite 1 largely concealed by pereonite 7, visible in dorsal view; pleonites posterior margin smooth, mostly concave; pleonite 2 partially overlapped by pereonite 7; pleonite 5 posterior margin slightly concave. Pleotelson 0.6 times as long as anterior width, dorsal surface smooth, lateral margins weakly concave, posterior margin converging to blunt caudomedial point.

Antennula comprised of 8 articles; articles 1 and 2 distinct and articulated with plumose setae; article 2 0.9 times as long as article 1; article 3 1.2 times as long as wide, 0.5 times as long as combined lengths of articles 1 and 2 with plumose seta; short simple setae present on last four articles, last article terminating in 4-8 short simple setae. Antenna comprised of 9 articles; article 3 1.3 times as long as article 2, 1.3 times as long as wide; article 4 1.4 times as long as wide, 1.1 times as long as article 3; article 5 as long as article 4, 1.4 times as long as wide; short simple setae on last three articles, last article terminating in 6-7 short simple setae.

Molar process present, mandible palp without setae. Maxillula with 4 terminal robust setae. Mxilla lateral lobe with 2 recurved robust setae; mesial lobe with 2 large recurved robust setae. Maxilliped comprised of 3 articles, palp article 2 without simple setae, article 3 with 3 recurved robust setae, and no simple setae.

Pereopods without robust or simple setae. Pereopod 1 basis 1.8 times as long as greatest width; ischium 0.6 times as long as basis; merus proximal margin without bulbous protrusion; carpus with straight proximal margin; propodus 1.4 times as long as wide; dactylus slender, 1.3 times as long as propodus, 2.6 times as long as basal width. Pereopod 2 propodus 1.3 as long as wide; dactylus 1.3 as long as propodus. Pereopod 7 basis 1.7 times as long as greatest width; ischium 0.7 as long as basis, without protrusions; merus proximal margin with slight bulbous protrusion, 0.4 as long as ischium, 0.6 times as long as wide; carpus 0.9 as long as ischium, without bulbous protrusion, 0.6 times as long as wide; propodus 0.9 as long as ischium, 1.3 times as long as wide; dactylus slender, 1.7 as long as propodus, 2.7 times as long as basal width.

Pleopod 1 exopod 1.3 times as long as wide, lateral margin weakly convex, distally narrowly rounded, medial margin weakly oblique, mesial margin strongly convex; endopod 1.8 times as long as wide, lateral margin weakly convex, distally narrowly rounded, mesial margin straight, peduncle 0.4 times as wide as long. Pleopods 2-5 similar to pleopod 1. Proximomedial lobes present and increasing in size from pleopod 1 to 5. Peduncle lobes absent.

Uropod more than half the length of pleotelson, peduncle 1.2 times longer than rami, peduncle lateral margin without setae; rami not extending beyond pleotelson, marginal setae absent, apices broadly rounded. Endopod apically rounded, 2.8 times as long as greatest width, lateral margin straight, mesial margin straight, terminating without setae. Exopod extending beyond endopod, 1.7 times longer than endopod, 4.2 times as long as greatest width, apically rounded, lateral margin straight, mesial margin straight, terminating without setae.

Male.

Males similar to females but smaller. Body more oval and not twisted, 2.1 times as long as wide. Maxilliped article three with three recurved robust setae. Maxilla with one recurved robust seta on the medial lobe and two on the lateral lobe. Penis set close together, medially united. Pleopod 2 appendix masculina basally swollen, 0.8 times as long as endopod, distally bluntly rounded. Pleotelson triangular converging to a sharp caudal point. Uropods extend past posterior margin of pleotelson and endopod is longer, exopod 1.5 times as long as endopod.

Size.

Ovigerous females (7.0-9.0 mm TL; 3.5-5.0 mm W), non-ovigerous females (7.0 mm TL; 3.0 mm W); mature male (6.0 mm TL; 4.0 mm W), immature males (5.5-6.0 mm TL; 2.0-2.5 mm W).

Etymology.

This species is named in honour of Ernest H. ( “Bert”) Williams Jr. and Lucy Bunkley-Williams on the occasion of their retirement and in recognition of their contribution to Caribbean marine parasitology; noun in apposition.

Distribution.

Known from St. John, St. Thomas, and Guana Islands, Caribbean Sea.

Hosts.

Only known from the redlip blenny, Ophioblennius macclurei (Silvester, 1915).

Remarks.

Mothocya bertlucy sp. n. can be identified by its unique host (redlip blenny), small size (like those reported from atherinids), relatively small eyes, the small pleotelson with a narrowly rounded caudomedial point, large uropod peduncle with short rami, uropods which do not extend past the pleotelson posterior margin, and the narrow pleon which is only slightly overlapped by pereonite 7.

The species most similar to Mothocya bertlucy sp. n. is Mothocya rosea Bruce, 1986 found on the Mexican and Californian coasts. In comparison to Mothocya bertlucy , Mothocya rosea has more produced proximomedial lobes on pleopods 3-5, larger eyes, broad truncate pleotelson, and four setae on the maxilliped article 3.

The three small Mothocya species from atherinids ( Mothocya argenosa ; Mothocya epimerica ; and Mothocya waminda Bruce, 1986) were all compared to the current species. Mothocya argenosa from the western Atlantic measures 5.6-9.8 mm, but has larger eyes, longer uropods, the pleotelson is more rounded and the posterolateral margins of pereonite 7 are acute. Mothocya epimerica from the Mediterranean has a more pointed rostrum, rounded pleotelson, larger eyes and four setae on the maxilliped. Mothocya waminda from the Indo-Pacific has an appendix masculina on pereopod 2 in the female and longer uropods.

Mothocya bertlucy sp. n. differs from all the other known Caribbean species in that Mothocya bohlkeorum has much larger and more produced coxae and a larger truncate pleotelson; Mothocya nana has a wider pleotelson, truncate rostrum and larger coxae; Mothocya bermudensis has an antennula with only seven articles, large eyes and an arched body; and Mothocya omidaptria has longer uropods extending past the pleotelson, a strongly produced rostrum and acute coxae as well as posterolateral angles of pereonite 7.

This is the first account of a Mothocya species from the US Virgin Islands and is also the first record on a blenny, which helps establish its status as a new species as Bruce (1986) commented that "host identity may be useful in making a Mothocya identification."