Sciadicleithrum Kritsky, Thatcher & Boeger, 1989

Bellay, Sybelle, Takemoto, Ricardo Massato, Yamada, Fábio Hideki & Pavanelli, Gilberto Cezar, 2009, Two new species of Sciadicleithrum (Monogenea: Dactylogyridae), gill parasites of Geophagus proximus (Castelnau) (Teleostei: Cichlidae), from the upper Paraná River floodplain, Brazil, Zootaxa 2081, pp. 57-66 : 58-59

Sciadicleithrum Kritsky, Thatcher & Boeger, 1989

Type-species: Sciadicleithrum uncinatum Kritsky, Thatcher & Boeger, 1989 from Cichla ocellaris Bloch & Schneider.

Others species: Sciadicleithrum tortrix Kritsky, Thatcher & Boeger, 1989 from Uaru amphiacanthoides Heckel ; Sciadicleithrum umbilicum Kritsky, Thatcher & Boeger, 1989 and Sciadicleithrum ergensi Kritsky, Thatcher & Boeger, 1989 from Cichla ocellaris Bloch & Schneider ; Sciadicleithrum geophagi Kritsky, Thatcher & Boeger 1989 from Geophagus surinamensis (Bloch) ; Sciadicleithrum iphthimum Kritsky, Thatcher & Boeger 1989 from Pterophyllum scalare ( Lichtenstein) ; Sciadicleithrum aequidens ( Price & Schlueter, 1967) Kritsky, Thatcher & Boeger, 1989 from Aequidens maroni (Steindachner) ; Sciadicleithrum cavanaughi ( Price, 1966) Kritsky, Thatcher & Boeger, 1989 from Aequidens maroni (Steindachner) ; Sciadicleithrum variabilum ( Mizelle & Kritsky, 1969) Kritsky, Thatcher & Boeger, 1989 from Symphysodon discus Heckel ; Sciadicleithrum mexicanum Kritsky, Vidal-Martínez & Rodriguez-Canul, 1994 from Cichlasoma urophthalmus (Günther) , Cichlasoma trimaculatum (Günther) , Parachromis dovii (Günther) , Parachromis managuense (Günther) , Tomocichla tuba (Meek) , Vieja maculicauda (= Cichlasoma maculicauda ) (Regan), Vieja synspila (= Cichlasoma synspilum )(Hubbs), Rocio octofasciata (= Cichlasoma octofasciatum ) (Regan), Parachromis friedchstahlii (Heckel) , Petenia splendida Günther , Theraps aureus (= Cichlasoma aureum )(Günther); Sciadicleithrum bravohollisae Kritsky, Vidal-Martínez & Rodriguez-Canul, 1994 from Cichlasoma pearsei (Hubbs) , Vieja synspila (Hubbs) , Petenia splendida Günther , Vieja fenestrata (Günther) , Vieja maculicauda (Regan) , Theraps lentiginosus (Steindachner) , Cichlasoma salvini (Günther) , Cichlasoma geddesi (Regan) , Parachromis managuensis (Günther) ; Sciadicleithrum splendidae Kritsky, Vidal-Martínez & Rodriguez-Canul, 1994 from Petenia splendida Günther and Parachromis friedrichstahlii (Heckel) ; Sciadicleithrum meekii Mendoza-Franco, Scholz & Vidal-Martínez, 1997 from Thorichthys meekii (= Cichlasoma meeki ) (Brind), Amatitlania nigrofasciata (= Archocentrus nigrofasciatus ) (Günther), Thorichthys callolepis (Regan) , Thorichthys helleri (Steindachner) ; Sciadicleithrum maculicaudae Vidal- Martínez, Scholz & Aguirre-Macedo, 2001 from Vieja maculicauda (Regan) ; Sciadicleithrum nicaraguense Vidal-Martínez, Scholz & Aguirre-Macedo, 2001 from Amphilophus alfari (Meek) ; Sciadicleithrum bicuense Vidal-Martínez, Scholz & Aguirre-Macedo, 2001 from Amatitlania nigrofasciata (Günther) ; Sciadicleithrum panamensis Mendoza-Franco, Aguirre-Macedo & Vidal-Martínez, 2007 from Aequidens coeruleopunctatus (Kner) ; Sciadicleithrum frequens Bellay, Takemoto, Yamada & Pavanelli, 2008 and Sciadicleithrum guanduensis Carvalho, Tavares & Luque, 2008 from Geophagus brasiliensis (Quoy & Gaimard) ; Sciadicleithrum joanae Yamada, Takemoto, Bellay & Pavanelli, 2009 from Crenicichla niederleinii (Holmberg) and Crenicichla britskii Kullander ; and Sciadicleithrum satanopercae Yamada, Takemoto, Bellay & Pavanelli, 2009 from Satanoperca pappaterra (Heckel) .

Emended diagnosis: Body divisible into cephalic region, trunk, peduncle, haptor. Tegument thin, smooth. Mouth subterminal, midventral; pharynx muscular, glandular; oesophagus present; intestinal ceca 2, confluent posteriorly, lacking diverticula. Four pair of head organs; 2 terminal, 2 bilateral cephalic lobes; unicellular cephalic glands composed of 2 groups posterolateral to pharynx. Eyes present; accessory granules. Gonads overlapping or slightly overlapping, intercecal, testis dorsal to ovary. Vas deferens looping around left intestinal cecum, seminal vesicle a dilation of vas deferens; 1 or 2 prostatic reservoirs. Male copulatory organ (MCO) composed of a base from which a coiled tube arises, a clockwise or counterclockwise coil of about less than 1 to more than 2 rings. Accessory piece present. Genital pore midventral at level of intestinal bifurcation. Oviduct short; uterus delicate, extending anteriorly along midline; seminal receptacle ventral to anterior end of ovary; vagina sinistral, dextral, or ventral. Vitelline follicles well developed, scattered throughout trunk. Haptor armed with dorsal and ventral pairs of unmodified anchors, ventral and dorsal bars, 7 pairs of similar hooks with ancyrocephaline distribution. Longitudinal lateral grooves on the shafts and points of ventral and dorsal anchors present or absent; hook shanks slender, thumb erect, variation in size present or absent; ventral bar with 1 or 2 variably developed umbelliform membranes or cavities on anterior bar margin; medial projection in bars present or absent; dorsal bar with umbelliform membranes present or absent. Parasites of gills of Neotropical Cichlidae (Perciformes) .

Remarks: When Sciadicleithrum was erected, six species were described ( S. uncinatum , S. tortrix , S. umbilicum , S. ergensi , S. geophagi , S. iphthimum ), and three species were presented as new combinations ( S. aequidens , S. cavanaughi , S. variabilum ) later another 12 species were described, which introduced characteristics not used in the original description of the genus: gonads slightly overlapping ( S. bravohollisae , S. cavanaughi , S. mexicanum , S. splendidae ), ventral bar with umbelliform membrane unique ( S. guanduensis ), longitudinal lateral grooves on the shafts and points of ventral and dorsal anchors ( S. bravohollisae , S. maculicaudae , S. mexicanum , S. nicaraguense , S. splendidae , S. frequens ), variation in the size of the hooks pairs ( S. frequens , S. satanopercae ), dorsal bar with umbelliform membranes ( S. nicaraguense , S. joanae ), medial projection in bars ( S. meekii ), and MCO with more 2 rings ( S. meekii , S. splendidae , S. tortrix , S. satanopercae ) ( Mendoza-Franco & Vidal-Martínez 2005; Mendoza-Franco et al. 2007; Bellay et al. 2008; Carvalho et al. 2008; Yamada et al. 2009). Although presence of a posteromedial projection in the ventral bar of S. meekii was not mentioned in the original description, Vidal-Martínez et al. 2001 illustrated this feature.