Tetrancistrum yamagutii, Kritsky & Galli & Tingbao, 2007

Kritsky, Delane C., Galli, Paolo & Tingbao, Yang, 2007, Dactylogyrids (Monogenoidea) parasitizing the gills of spinefoots (Teleostei, Siganidae): revision of Tetrancistrum Goto and Kikuchi, 1917, with descriptions of two new species from Siganus spp. of the Red Sea and Celebes, Journal of Natural History 41 (25 - 28), pp. 1513-1551 : 1532-1534

Tetrancistrum yamagutii sp. n.

( Figures 35–40 )

Description. Body foliiform; trunk broad; cephalic region and peduncle tapered; greatest body width near body midlength. Cephalic lobes moderately developed; each head organ comprising several groups of terminations of cephalic-gland ducts; small bilateral groups of cephalic glands posterolateral to pharynx. Eyespots absent or dissociated; accumulations of chromatic granules randomly distributed anterior to pharynx; minute subovate granules scattered throughout cephalic region and anterior trunk. Pharynx elongate to subspherical; intestinal caeca lack diverticula. Testis ovate; vas deferens and seminal vesicle not observed; prostatic reservoirs conspicuous, lie dorsal to copulatory complex. Copulatory complex comprises articulated MCO and accessory piece. MCO tubular, uniform in diameter (except proximal end enlarged), with double proximal recurve; accessory piece a distally flattened rod arising proximally from foot-shaped base. Germarium comparatively large, conical; ootype receives vaginal duct and bilateral vitelline ducts; uterus midventral, extends along body midline to genital atrium; vaginal pore at level of copulatory complex; vaginal vestibule large, elongate; vaginal tube short, expanded; vitellarium dense. Haptoral hooks absent. Ventral and dorsal anchors typical; roots of ventral anchor subequal in length. Ventral bar straight; dorsal bar flat, broadly U-shaped.

Measurements. Body 712 (689–736; n 52) long; greatest width 195 (190–201; n 52). Haptor 82 (78–85; n 52) long, 70 (56–84; n 52) wide. Pharynx 37 (36–38; n 52) wide. Copulatory complex 97 (94–100; n 52) long. Ventral anchor 69 (66–72; n 52) long; base 34 (n 51) wide. Dorsal anchor 72 (71–74; n 52) long; base 22 (n 51) wide. Ventral bar 21 (n 51) long; dorsal bar 28 (25–30; n 52) long. Germarium 70 (n 51) long, 81 (n 51) wide; testis 96 (90–102; n 52) long, 84 (81–86; n 52) wide.

Type host and locality. Siganus sp.: Macassar, Celebes.

Site of infestation. Gills.

Specimens studied. Holotype, paratype, MPM 23010 .

Etymology. The new species is named in recognition of Dr S. Yamaguti’s massive contributions to our present knowledge and understanding of helminth diversity and taxonomy.

Remarks. The holotype and paratype of T. yamagutii were found on an MPM slide labelled (22838, 22839) and containing the type specimens of Pseudohaliotrema (Pseudohaliotrematoides) fusiforme and Pseudohaliotrema (Pseudohaliotrema) sphincteroporus , both of which were described by Yamaguti (1953). The new species most closely resembles T. sigani and T. indicum . It is differentiated from these species by possessing a doubly

recurved proximal portion of the tube of the MCO. It differs further from T. indicum by having an articulated MCO and accessory piece.

Figures

Figures 35–40. Tetrancistrum yamagutii sp. n. from Siganus sp., Macassar. (35) Whole mount (composite, ventral view). (36) Copulatory complex. (37) Dorsal bar. (38) Ventral bar. (39) Ventral anchor. (40) Dorsal anchor. Scale bar: 200 Mm (35); 30 Mm (36–40).