Diaphorocleidus altamirensis, Moreira & Scholz & Luque, 2016

Moreira, Juliana, Scholz, Tomáš & Luque, José Luis, 2016, A new species of Diaphorocleidus (Monogenea: Ancyrocephalinae) from the gills of Argonectes robertsi (Characiformes) and new records of dactylogyrids parasitic on fishes from the Xingu River, Amazon Basin, Brazil, Zoologia (e 20160022) 33 (4), pp. 1-6 : 2-4

Diaphorocleidus altamirensis sp. nov.

Figs. 1-8

urn:lsid:zoobank.org:act:4E69D9B9-3DE2-44AF-91E3-1D93BC1B61CC

Description (based on 6 specimens): Body fusiform 345- 414 (367, n = 6) long; greatest width 53-68 (62, n = 6) usually at level of gonads. Cephalic lobes poorly developed; 3 bilateral pairs of head organs; cephalic glands indistinct. Eyespots 2; accessory granules present in cephalic region. Pharynx spherical 13-24 (17, n = 6) in diameter; esophagus moderately long. Peduncle broad; haptor hexagonal, 56-71 (64, n = 6) wide. Ventral anchor 45-50 (47, n = 6) long, with well-developed and elongate superficial root, shorter deep root, curved shaft and point; base 21-26 (23, n = 6) wide. Dorsal anchor 33-36 (34, n = 6) long, with well-developed superficial root, short deep root, straight shaft and curved point; base 14-20 (17, n = 6) wide. Ventral bar 40-57 (44, n = 6) long, with medial suture and expanded ends; dorsal bar 24-36 (30, n = 6), slender, widely U-shaped, with slightly expanded ends. Hooks similar each with protruding thumb, curved shaft and point, dilated shank; pairs 1 and 5 reduced in size; filamentous hooklet (FH) loop -½ shank length; hook pairs 1, 5 – 9-13 (11, n = 6) long; hook pair 2 – 16-20 (18, n = 6) long; hook pair 3 – 16-26 (20, n = 6); hook pairs 4, 6, 7 – 11-24 (19, n = 6) long. MCO comprising a delicate coil of 6 counterclockwise rings, base with lateral flange, diameter of first ring 8-12 (10, n = 5). Accessory piece 14-30 (22, n = 5) long, comprising two articulated subunits, distal subunit bifurcate, proximal subunit curved and elongate, serving as guide for MCO. Vaginal aperture midventral, a coiled tube leading into a medial seminal receptacle anterior to germarium. Gonads overlapping; germarium 40-54 (45, n = 3) long. Testis dorsal, slightly visible at end of germarium; seminal vesicle a distal expansion of vas deferens; prostatic reservoir single. Oviduct, ootype and uterus not observed. Vitellarium scattered throughout trunk, except in regions of reproductive organs.

Type host: Argonectes robertsi Langeani, 1999 (Characiformes, Hemiodontidae ).

Site of infection: Gills.

Type locality: Xingu River around Altamira (3°12’S, 52°12’W), state of Pará, Brazil.

Type specimens: Holotype and five paratypes deposited as CHIOC 38406a-f .

Etymology: This species is named for the type locality from which it was collected.

Remarks. Diaphorocleidus includes species with overlapping gonads, submarginal sinistral vaginal pore, a coiled male copulatory organ with counterclockwise rings, unarticulated to accessory piece and hook shank with two subunits. The midventral vaginal aperture of D. altamirensis sp. nov. is the only major difference of this species from congeners, but this unusual vaginal morphology does not seem us to justify proposal of a new genus. In addition to the position of the vagina, D. altamirensis differs from all congeners by having a male copulatory organ with 6 counterclockwise rings (2-3 in D. affinis , 2 in D. armillatus , 1-1½ in D. kabatai and in D. petrosusi , 1½-2½ in D. microstomus and 1 in D. orthodusus ), by the accessory piece comprising two subunits (distal bifurcate and proximal curved and elongate) and by the presence of just one pair of eyespots. Diaphorocleidus petrosusi also possesses an accessory piece subdivided in two parts, plate-shaped, but D. altamirensis sp. nov. can be easily distinguished by the haptoral structures and by the coiled vaginal tube (a nondilated sclerotized in D. petrosusi ), which is also an unique feature of this new species. None of the two dactylogyrids recorded from H. semitaeniatus 6 in Brazil, i.e., C. microcirrus and M. lavergneae , shows similarity with D. altamirensis .

New host and geographical records. In addition to the new species described above, another seven species of gill monogeneans of the family Dactylogyridae were found on four species of fishes during parasitological surveys carried out in the Xingu River. All fishes represent new hosts of these monogeneans and except for Jainus amazonensis Kritsky, Thatcher & Kayton, 1980 , all parasites are reported from the Xingu River, Amazon basin, for the first time ( Table 1 ).

Figures

Figures 1-8. Diaphorocleidus altamirensis sp. nov.: (1) whole mount (composite, ventral view); (2) ventral anchor; (3) dorsal anchor; (4) ventral bar; (5) dorsal bar; (6) hook (pair 2); (7) hook, pair 5; (8) copulatory complex (dorsal). Scale bars: 1 = 100 µm, 2-5 = 25 µm, 6-7 = 10 µm, 8 = 20 µm.