Haliotrematoides, Kritsky, Yang & Sun, 2009

Kritsky, Delane C., Tingbao, Yang & Yuan, Sun, 2009, Dactylogyrids (Monogenoidea, Polyonchoinea) parasitizing the gills of snappers (Perciformes, Lutjanidae): Proposal of Haliotrematoides n. gen. and descriptions of new and previously described species from marine fishes of the Red Sea, the eastern and Indo-west Pacific Ocean, Gulf of Mexico and Caribbean Sea, Zootaxa 1970 (1970), pp. 1-51 : 7-9

Haliotrematoides n. gen.

Type species: Haliotrematoides hatzenbuehlerae n. sp. from Lutjanus adetii (Lutjanidae) .

Other species: H. brachyflagellocirrus ( Wang, Liu & Zhou, 2003) n. comb. from L. argentimaculatus (Lutjanidae) . H. caesionis ( Yamaguti, 1953) n. comb. from Caesio cuning (Caesionidae) . H. calcaris ( Bychowsky & Nagibina, 1971) n. comb. from Lutjanus sp. (Lutjanidae) . H. cornigerum ( Zhukov, 1976) n. comb. from L. synagris and L. mahogoni (both Lutjanidae ). H. gracilihamus ( Zhukov, 1976) n. comb. from L. griseus , L. jocu , L. cyanopterus , L. aratus , L. mahogoni and L. apodus (all Lutjanidae ). H. guttati ( García-Vargas, Fajer-Ávila & Lamothe-Argumedo, 2008) n. comb. from L. guttatus (Lutjanidae) . H. heteracantha ( Zhukov, 1976) n. comb. from L. analis , L. griseus , L. synagris , L. mahogoni , L. apodus and Ocyurus chrysurus (all Lutjanidae ). H. isolens n. sp. from Pterocaesio marri (Caesionidae) . H. lanx Kritsky & Justine n. sp. from L. quinquelineatus (Lutjanidae) . H. longihamus ( Zhukov, 1976) n. comb. from L. griseus , L. mahogoni , L. synagris and L. analis (all Lutjanidae ). H. longitubocirrus ( Bychowsky & Nagibina, 1971) n. comb. from L. lutjanus , L. vitta , L. russellii , L. fulvus and L. quinquelineatus (all Lutjanidae ). H. magnigastrohamus ( Zhukov, 1976) n. comb. from L. analis , L. mahogoni , L. synagris and Ocyurus chrysurus (all Lutjanidae ). H. mastigion Kritsky & Mendoza-Franco n. sp. from L. argentiventris (Lutjanidae) . H. mediohamides Kritsky & Mendoza-Franco n. sp. from Calamus brachysomus (Sparidae) . H. mediohamus ( Zhukov, 1983) n. comb. from C. calamus and C. bojonado (both Sparidae ). H. nagibinae n. sp. from L. argentimaculatus (Lutjanidae) . H. noncalcaris ( Bychowsky & Nagibina, 1971) n. comb. from L. argentimaculatus (Lutjanidae) . H. noncalcaroides n. sp. from L. argentimaculatus (Lutjanidae) . H. novaecaledoniae Kritsky & Justine n. sp. from L. argentimaculatus (Lutjanidae) . H. overstreeti Kritsky & Bullard n. sp. from L. cyanopterus (Lutjanidae) . H. parvicirrus ( Zhukov, 1983) n. comb. from C. calamus and C. bojonado (both Sparidae ). H. patellacirrus ( Bychowsky & Nagibina, 1971) n. comb. from L. lutjanus , L. russellii , L. vitta , L. fulviflamma , L. fulvus , L. quinquelineatus and L. ehrenbergii (all Lutjanidae ). H. plectridium Kritsky & Mendoza-Franco n. sp. from L. guttatus (Lutjanidae) . H. potens Kritsky & Justine n. sp. from L. argentimaculatus (Lutjanidae) . H. prolixohamus Kritsky & Medoza-Franco n. sp. from C. brachysomus (Sparidae) . H. shenzhenensis ( Wang, Liu & Zhou, 2003) n. comb. from an apparent secondary or unnatural host, Sciaenops ocellatus (Sciaenidae) . H. spinatus Kritsky & Mendoza-Franco n. sp. from L. guttatus (Lutjanidae) . H. tainophallus Kritsky & Justine n. sp. from L. fulviflamma (Lutjanidae) . H. zhukovi Kritsky & Bullard n. sp. from L. mahogoni (Lutjanidae) .

Diagnosis: Body fusiform, slightly flattened dorsoventrally, comprising body proper (cephalic region, trunk, peduncle) and haptor. Tegument smooth. One terminal, 2 bilateral cephalic lobes; 3 pairs of bilateral head organs, each comprising groupings of terminations of cephalic-gland ducts; cephalic glands posterolateral to pharynx. Four eyespots; chromatic granules minute, subovate; accessory granules few or absent in cephalic region and anterior trunk. Mouth subterminal, midventral at level of eyespots, opening into buccal tube; buccal tube extending posteriorly to pharynx; pharynx a muscular glandular bulb; esophagus short; intestinal caeca two, confluent posterior to gonads, lacking diverticula. Common genital pore midventral, usually posterior to intestinal bifurcation. Gonads tandem, intercaecal; germarium pretesticular. Proximal portion of vas deferens extending anteriorly from testis along body midline dorsal to female reproductive organs, then looping left intestinal caecum anterior to germarium; seminal vesicle a simple dilation of vas deferens; prostate anterodorsal to male copulatory organ (MCO); single prostatic reservoir. MCO tubular, a coiled tube arising from base; coil clockwise or counterclockwise. Accessory piece absent. Germarium comprised of few oocytes; oviduct short, receiving common vitelline duct and ducts from seminal receptacle and Mehlis’ gland; seminal receptacle a simple expansion of vaginal canal slightly to right of body midline; uterus extending anteriorly along body midline to common genital pore. Vaginal pore dextromarginal; vagina usually with distal vestibule, tubular canal extending to seminal receptacle. Vitellarium coextensive with gut, absent in regions of other reproductive organs; bilateral vitelline ducts converge anterior to germarium to form common vitelline duct emptying into ootype. Haptor a simple extension of peduncle, armed with dorsal and ventral anchor/bar complexes and variable number of hooks (depending on hook distribution). Ventral anchor with superficial and deep roots, elongate shaft, recurved point; distal portion of shaft and/or point usually with longitudinal surface grooves. Dorsal anchor with perforated base, elongate depressed superficial root, poorly developed (or absent) deep root, elongate shaft, strongly recurved point; distal portion of shaft and/or point usually with longitudinal superficial grooves. Ventral bar usually with two submedial pockets on anterior margin. Seven pairs of similar hooks; pairs 1, 2, 3 on ventral surface of peduncle (pairs 2, 3 may extend anteriorly on trunk to level of testis); pair 7 on dorsal surface of peduncle; pair 5 associated with points and shafts of ventral anchors; pairs 4, 6 on respective ventral and dorsal surfaces of haptor at level of anchor bases; one or both latter two pairs may be shifted forward to junction of peduncle and haptor. Hook with upright acute thumb, slender shank comprising single subunit; filamentous hook (FH) loop slightly shorter than hook shank. Parasites of gills of marine fishes ( Lutjanidae , Caesionidae and Sparidae ).

Remarks: The diagnosis of Haliotrematoides includes features in common with those of Euryhaliotrema , Euryhaliotrematoides Plaisance & Kritsky, 2004 and some species in Haliotrema (s. l.). In part, these include a dextromarginal vaginal pore, tandem gonads (germarium pretesticular), hooks with upright acute thumbs, a vas deferens looping the left intestinal caecum and confluent intestinal caeca. The new genus is differentiated from these genera (and species) by its members having 1) an unique hook distribution including all pairs, except pair 5 and usually pairs 4 & 6, located on the peduncle or posterior trunk anterior to the anchor/bar complexes; 2) a copulatory complex lacking an accessory piece; 3) dorsal anchors with perforated bases lacking well-developed deep roots, elongate relatively straight shafts and superficial grooves on the distal portion of the shafts and/or points; 4) ventral anchors with developed basal roots, elongate shafts and grooved distal portion of the shafts and/or points; and 5) a ventral bar generally with two submedial pockets along the anterior margin. These combined features distinguish Haliotrematoides from all other dactylogyrid genera.

Some species of Haliotrematoides , including the type species H. hatzenbuehlerae , possess blades on the inner surfaces of the anchor shafts. However, blades are not present in all species and are not restricted to members of this genus. They have been reported from species of other dactylogyrid genera, including Pterocleidus Mueller, 1937 , Haliotrema (s. l.), and Dactylogyrus Diesing, 1850 , among others, and from species of Rhabdosynochus Mizelle & Blatz, 1941 within the Diplectanidae , suggesting that blades developed independently many times within the suborder Dactylogyrinea and probably have little significance for defining taxa above the species level. Although blades may have phylogenetic significance within Haliotrematoides , it is uncertain whether their presence represents a synapomorphy or a secondary feature within the genus. Character analysis using the presumed outgroups Euryhaliotrema , Haliotrema (s. l.) and Euryhaliotrematoides , however, suggests that blades are secondary with probable occurrences of subsequent loss in Haliotrematoides .

DNA samples were available from only four species of Haliotrematoides : H. brachyflagellocirrus , H. noncalcaris , H. noncalcaroides and H. nagibinae all from L. argentimaculatus in China. Although the number of species of Haliotrematoides available for molecular analyses was small, phylogenetic analyses of both total 18S rDNA and partial 28S rDNA support Haliotrematoides as a natural apparently monophyletic taxon. Results from total 18S rDNA, including that of H. brachyflagellocirrus , H. noncalcaris and H. nagibinae , produced a most parsimonious cladogram (length = 1192; consistency index = 0.5604; retention index = 0.7375; and rescaled consistency index = 0.4133) that did not resolve the basal origins of the genus among the 24 ingroup species, although it did indicate that the three species of Haliotrematoides formed a monophyletic clade with 100% bootstrap support ( Fig. 1). Inspection of the cladogram developed from 28S rDNA (length = 2223; consistency index = 0.4993; retention index = 0.7056; and rescaled consistency index = 0.3523) and including H. brachyflagellocirrus , H. noncalcaroides and H. nagibinae , provided additional support for the monophyletic status of the genus (100% bootstrap support). The origin of Haliotrematoides using 28S rDNA data, however, is suggested to have occurred within the paraphyletic clade of the 19 Haliotrema species subjected to study ( Fig. 2).