Hexabothriids of Devil Rays (Mobulidae): New Genus and Species from Gill ofMobula hypostomain the Northern Gulf of Mexico and Redescription of a Congener FromMobula rochebruneiin the Eastern Atlantic Ocean

Abstract

A new species of Hexabothriidae, Mobulicola enantiomorphica n. gen., n. sp., is described on the basis of specimens collected from the gill of a lesser devil ray, Mobula hypostoma (Bancroft, 1831) (Rajiformes: Mobulidae), captured in the northern Gulf of Mexico (30°13'49.22″N, 88°20'31.69″W) off Dauphin Island, Alabama. We also herein redescribe Mobulicola dubium (Euzet and Maillard, 1967) n. comb. on the basis of the holotype (36HG-69-1) and paratypes (36HG-69-2 and 36HG-69-3) collected from the gill of a lesser Guinean devil ray, Mobula rochebrunei (Vaillant, 1879), captured in the eastern Atlantic Ocean off the island of Gorée (14°40'02.26″N, 17°23'4.96″W), Senegal. Mobulicola has the following combination of diagnostic features that differentiate it from other hexabothriid genera: haptor symmetrical; vasa efferentia narrow for entire length (not dilated distally), glandular-walled, joining medially immediately anterior to testicular field; vas deferens glandular for part or all of length and extensively convoluted; male copulatory organ massive, oblong, unarmed, dilated for entire length, lacking prostatic region; seminal receptacle present; ootype lacking longitudinal rows of large cells (ootype côtelé); vaginae parallel, with well-differentiated proximal (narrow, tube-like) and distal (laterally expanded, musculoglandular) portions; uterine eggs with 2 elongate filaments. Mobulicola is morphologically most similar to Branchotenthes Bullard and Dippenaar, 2003 but differs from it by the combination of having short, delicate vasa efferentia that are narrow for their entire length and that each extends slightly anteriad from the testicular field before uniting medially, a vas deferens that is convoluted between the common vitelline duct and male copulatory organ, an ovate, compact seminal receptacle, an ovary that ascends, descends, then ascends, and a proximal uterus that is extensively convoluted posterior to the male copulatory organ. The new species differs from M. dubium by the combination of having a proportionally shorter sclerite hook (19-29% of sclerite shaft total length), a vas deferens that is glandular-walled and laterally expanded proximally and nonglandular and narrow distally, and a common vitelline duct with dextral and sinistral loops extending anteriad. This is only the second report of a hexabothriid from a mobulid and the first report of a monogenoid from Mobula hypostoma.

Lesser devil rays Mobula cf. hypostoma from Venezuela are almost twice their previously reported maximum size and may be a new sub‐species

“…A subsequent specimen from New Jersey was 108 inches wide (274·3 cm) (Fowler, ), but its large size cast doubt about whether it truly was M. hypostoma , or another species [devil ray Mobula mobular (Bonnaterre 1788)] that originated from European waters (Bigelow & Schroeder, ). A beach‐cast specimen, however, recovered in 1965 in Venezuela that was probably M. hypostoma , was 150 cm disc width ( W D ) (Cervigón & Alcalá, ) and a more recent specimen caught off Alabama was 129 cm W D (Patella & Bullard, ). Collectively, these sparse observations have led to the commonly reported conclusion that M. hypostoma attain a maximum W D of 120 cm (Robins & Ray, ; Cervigón & Alcalá, ; McEachran & Carvalho, ; Tobón‐López et al ., ; Navia & Mejía‐Falla, ).…”

“…150 cm disc width (W D ) (Cervigón & Alcalá, 1999) and a more recent specimen caught off Alabama was 129 cm W D (Patella & Bullard, 2013). Collectively, these sparse observations have led to the commonly reported conclusion that M. hypostoma attain a maximum W D of 120 cm (Robins & Ray, 1986;Cervigón & Alcalá, 1999;McEachran & Carvalho, 2002;Tobón-López et al, 2011;Navia & Mejía-Falla, 2014).…”

Hexabothriid monogeneans from the gills of deep-sea sharks off Algeria, with the description of Squalonchocotyle euzeti n. sp. (Hexabothriidae) from the kitefin shark Dalatias licha (Euselachii, Dalatiidae)

“…The number of genera included in the family has slowly increased from eleven (Euzet & Maillard, 1974) and thirteen (Boeger & Kritsky, 1989) to a total of fi fteen in most (Patella & Bullard, 2013). However, the hexabothriid literature is plagued with confusion and discrepancies (Vaughan & Christison, 2012) but probably no more than any large family of monogeneans.…”

“…(Table 2). It cannot be excluded, however, that some of the small species were described from immature specimens, as it was the case for Mobulicola dubium (Euzet & Maillard, 1974) Patella & Bullard, 2013(Euzet & Maillard, 1967Patella & Bullard, 2013). Squalonchocotyle euzeti is differentiated from S. laymani by much longer sclerites (ca 2,000 vs ca 600), different hosts (Dalatias licha vs Mustelus manazo) and widely separated localities (Mediterranean vs Japan).…”

Neonchocotyle violantei n. sp. (Monogenea, Hexabothriidae) from Pseudobatos lentiginosus (Rhinopristiformes, Rhinobatidae) of Yucatán, Gulf of Mexico

“…Hexabothriidae Price, 1942 (Monogenea) includes 16 genera and approximately 77 species, although recent authors do not agree on those numbers (BOEGER & KRITSKY, 1989, 13 genera;PATELLA & BULLARD, 2013;KHEDDAM et al, 2016, 15), often not including Pristonchocotyle Watson & Thorson, 1976. Members of the family infect the gills of Chondrichthyes (BOEGER & KRITSKY, 1989).…”