Acanthoplacatus amplihamus Ernst & Jones & Whittington 2001, sp. nov.
Creators: name: Ernst, Ingo
name: Jones, Malcolm K.
name: Whittington, Ian D.
Publisher: name: Zenodo
Year: 2001
Subjects: Biodiversity
Taxonomy
Animalia
Platyhelminthes
Monogenea
Gyrodactylidea
Gyrodactylidae
Acanthoplacatus
Acanthoplacatus amplihamus

description: Acanthoplacatus amplihamus sp. nov.   
(Figures 3, 5A ±D)  
 Type host. Siganus punctatus (Forster, 1801) (Siganidae).   
 Type locality. Heron Island, Great Barrier Reef, Queensland, Australia.   
 Site on host. This species was found most frequently on the body surfaces (see table 1).   
 Holotype. QM 215976.   
 Paratypes. QM 215977 ±8.   
 Etymology. This species is named from the Latin (amplus 5 large, hamus 5 hook) for the large size of its hamuli.   
 Infection details. Prevalence 57%, seven ®sh examined, LCF 171 mm (126± 211 mm); intensity 2±62, two ®sh examined, LCF 152±159 mm.   
 Description. Sclerite measurements taken from 16 worms mounted in Malmberg’s ®xative. For this species measurements of soft body organs were also taken from the same 16 specimens. Numerous live worms examined for the structure of soft body organs and excretory system. Total length 627 (498±752, n 5 10), maximum width 155 (119±209, n 5 13) (®gure 5A) at level of uterus when embryo contained within or testis for worms with small embryo. Hamulus length 58.5 (55.5±61, n 5 16); hamulus point length 24.5 (23.5±26.5, n 5 16); hamulus root length 32 (29±34.5, n 5 16); hamulus shaft length 40.5 (38 ±42, n 5 16). Hamulus shafts with distinct longitudinal depression anteroventrally (®gure 5D). Dorsal root tissue cap length 12 (10.5±13, n 5 16), width 5 (4±6, n 5 15). Ventral bar with single medial anterior projection; slightly variable in shape (®gures 3, 5D). Ventral bar 19.5 (18±22, n 5 15) long (including anterior projection), 19.5 (18±21, n 5 15) wide. Ventral bar membrane 29 (27±32, n 5 15) long. Total length of ventral bar and membrane 48.5 (46±52, n 5 15). Transition between ventral bar and ventral bar membrane not distinct. Marginal hooks small with hook point extending to, or only slightly past toe; total length of marginal hook 33 (31±34.5, n 5 16); length of sickle 4 (4±4.5, n 5 16); length of handle 29.5 (28±31, n 5 16) (®gure 5B).   
 Gland cells anterolateral to pharynx range from minimum diameter of 19.5 (13±23, n 5 9) to maximum diameter of 27 (20±38, n 5 9). Anterior lobe of pharynx 45.5 (32±54, n 5 12) wide, posterior lobe 62 (45±76, n 5 12) wide. Gut caeca extend posteriorly lateral to uterus, terminating posterior to testis. Male copulatory organ with one large, two moderate and three small spines (11 21 3) (®gure 5D). Male copulatory organ 16 (11±19, n 5 5) long, 16 (14±19, n 5 5) wide. Developing sclerites of F2 embryos may be visible within large F1 embryos; no sclerites of F3 embryos visible. Oocyte 25 (14±46, n 5 12) long, 44 (31±61, n 5 12) wide, contained within ECFR. Testis 24.5 (10±36, n 5 11) long; 37.5 (16±51, n 5 11) wide. Five cells surround posterior portion of each gut caecum and single cell lies medially near posterior terminations; cells range from minimum diameter of 23 (17±26, n 5 12) to maximum diameter of 41.5 (33±52, n 5 12) (®gure 5A).   
 Comments. Acanthoplacatus amplihamus sp. nov. is the most distinctive species in the genus because the ventral bar and hamuli are much larger than other species (table 2) and a distinct anterior projection occurs on the ventral bar (®gure 5D). The male copulatory organ, with a 11 21 3 con®guration, is unlike that of all species except A. parvihamus sp. nov. Location of the posterior gland cells relative to the gut could not be determined for this species because only ¯attened specimens were available for study.
description: Published as part of Ernst, Ingo, Jones, Malcolm K. & Whittington, Ian D., 2001, A new genus of viviparous gyrodactylid (Monogenea) from the Great Barrier Reef, Australia with descriptions of seven new species, pp. 313-340 in Journal of Natural History 35 (3) on pages 323-325, DOI: 10.1080/002229301300009568, http://zenodo.org/record/4757237