Characithecium Mendoza-Franco, Reina &Torchin, 2009

Characithecium Mendoza-Franco, Reina &Torchin, 2009

Type species. Characithecium costaricensis ( Price & Bussing, 1967) Mendoza-Franco, Reina & Torchin, 2009

Type host. Astyanax aeneus (Günther) (Characidae) .

Type l ocality. Central America, from southeastern Mexico to Panama.

Other species. Characithecium chascomusensis n. comb. Instead of Characithecium comb. n. C. longianchoratum n. sp., C. robustum n. sp., C. quadratum n. sp., C. chelatum n. sp.

Other localities. The Pampasic region, Argentina.

Emended diagnosis. Body comprising cephalic region, trunk, peduncle and haptor. Tegument thin and smooth. Cephalic lobes developed, head organs and cephalic glands present. Eyespots present. Mouth midventral; pharynx muscular; esophagus short, 2 intestinal ceca confluent posterior to gonads, lacking diverticula. Gonads intercecal, overlapping; testis dorsal to germarium. Seminal vesicle as dilation of vas deferens with distal loop before reaching base of male copulatory organ (MCO); single prostatic reservoir present. Copulatory complex comprising an articulated MCO and accessory piece. MCO coiled tube with counterclockwise rings, with dilated and reel shaped base; articulation process present, lying within rings of MCO. Accessory piece, clamp shaped, comprising 2 subunits. Genital pore midventral near level of cecal bifurcation. Seminal receptacle pregermarial; vagina single, sclerotized or slightly sclerotized; opening sinistral, midventral, lateroventral, or in marginal position. Vitellaria follicular, restricted to trunk and coextensive with intestine. Haptor with 7 pairs of hooks with ancyrocephaline distribution, being pairs 1 and 5 reduced in size, 2 pairs of anchors with developed roots and U shaped bars. Hooks similar, each with depressed thumb, delicate point, and shank comprising 2 subunits (proximal subunit expanded).Ventral anchor larger than dorsal anchor. Ventral bar with dilated extremities and posterormedial projection present or absent.

Remarks. Characithecium was erected by Mendoza-Franco et al. (2009) to accommodate Urocleidoides costaricensis Price & Bussing, 1967 , a species considered incertae sedis by Kristy et al. (1986) in their emendation of Urocleidoides . Characithecium costaricensis ( Mendoza-Franco et al. 2009) has been extensively reported from southern and central Mexico and Nicaragua from different species of Astyanax . The characteristics shared by the 5 species found in O. jenynsii that allowed their inclusion in Characithecium are: (1) eyes present; (2) overlapping gonads (testis dorsal to germarium); (3) a seminal vesicle formed by a simple dilation of the vas deferens; (4) an articulated MCO and accessory piece; (5) MCO with a coiled shaft in counterclockwise direction; (6) ventral anchor larger than dorsal anchor; and (7) hook shanks, each composed of 2 subunits (proximal subunit expanded) ( Mendoza-Franco et al. 2009). Additional characters observed in the 5 new species required to extend the generic diagnostic features to include the vaginal aperture position (as midventral, lateroventral or lateromarginal) and the variability in the morphology of ventral bar (posteromedial projection present or absent).