Transversotrema atkinsoni, Hunter, Janet A. & Cribb, Thomas H., 2012

Hunter, Janet A. & Cribb, Thomas H., 2012, A cryptic complex of species related to Transversotrema licinum Manter, 1970 from fishes of the Indo-West Pacific, including descriptions of ten new species of Transversotrema Witenberg, 1944 (Digenea: Transversotrematidae), Zootaxa 3176, pp. 1-44 : 20-21

Transversotrema atkinsoni n. sp.

( Fig. 4 )

Syn. T. licinum of Cribb et al. (1992) in part

Type-host: Scolopsis monogramma (Cuvier) (Nemipteridae) , Monogrammed monocle bream

Type-locality: Heron Island, southern GBR, Queensland, Australia. (23°27’S 151°55’E)

Other locality: Ningaloo Reef (21°30’S 114° 3 0’E) Western Australia

Other hosts: Scolopsis bilineatus (Bloch) , Two-lined monocle bream; Scolopsis lineata Quoy & Gaimard. Striped monocle beam,

Site: Beneath the scales

Material examined: Table 7

Molecular sequence data: ITS2 rDNA

GenBank accession numbers: see Table 2

Deposited specimens: Holotype QM G231819 (ex S. monogramma HI coll. Ingram 3 Apr 2003), paratypes QM G231820 (ex S. monogramma HI coll. Cribb et al. Jul 1994), QM G231821 (ex S. monogramma HI coll. Ingram May 2003), QM GL12758 (ex S. monogramma HI coll. Cribb Nov 1989), QM GL12759 (ex S. monogramma HI coll. Cribb Nov 1989).

Etymology: This species is named for Glenn Atkinson who has been most helpful with his advice on computer technology used in this study.

Description: Based on measurements of 9 specimens from nemipterids from Heron Island and Ningaloo Reef. Body transversely elongated, strongly dorsoventrally flattened, 426–875 (609) long, 1,476–2,779 (2,005) wide; average width/length range 3.3:1. Pharynx to anterior margin 108–233 (166), cyclocoel to posterior margin 91–172 (134). Anterior margin curved. Tegumental spines prominent in offset rows. Eyespots prominent, 152–298 (151) apart (7.5%) of body width; positioned beside pharynx; no pigment evident other than in eyespots. Ventral sucker well posterior to eyespots, 3948–13007 (6863)μm2. Mouth mid-ventral, inconspicuous. Pharynx between eyespots, 68–154 (116) long, 78–163 (123) wide. Oesophagus curved 62–135 (114) long. Caecal bifurcation dorsal to ventral sucker. Caeca form cyclocoel reaching laterally to envelop testes, ovary and some vitelline follicles. Testes opposite, deeply lobed, left, 12,949–50,836 (28,912) μm2; right 11,336–50,405 (27,176) μm2. Seminal vesicle formed of lobed, saccular enclosed portion and winding, tubular extracaecal portion. Enclosed portion distinctly lobed or entire, antero-dextral to right of testis, constricts distally to form narrow duct that passes ventral to cyclocoel to join tubular portion. Tubular portion of seminal vesicle passes mediad along cyclocoel then turns anteriorly and passes between eyespots dextral to pharynx and passes to common genital pore where it unites with uterus without any specialisation. Common genital pore precisely in midline on anterior margin of worm. Ovary sinistral to left testis usually five prominent extended lobes, 3890–20039 (8957) μm2. Oviduct passes medio-posteriorly, unites with Laurer’s canal and duct from oviduct passes vitelline reservoir, then passes posteriorly to open dorsally close to left testis; median portion dilated, contains sperm or vitelline remnants. Vitelline reservoir immediately anterior to left testis. Extracaecal vitelline follicles small, confluent, lateral and posterior to cyclocoel, do not extend beyond anterior margin of cyclocoel; posterior follicles in rows of three or four. Enclosed follicles in two loosely assembled masses at each lateral extremity, 48–72 (61) with some follicles scattered posterior to testes along inner margins of cyclocoel. Uterus passes medially between anterior half of cyclocoel and testes then between right testis and saccular portion of seminal vesicle. Proximal portions of uterus act as seminal receptacle. Eggs tanned, length 88–138 (106), width 38–98 (64) (approximately 3% of body width), few in utero (0–4). Excretory bladder opens posteriorly at small notch in middle of posterior margin, extends anteriorly initially as narrow tube which then expands into large sac which passes ventral to cyclocoel anterior to which it becomes laterally directed.

Remarks: Transversotrema atkinsoni n. sp. resembles T. licinum in having a crescent shape, but the anterior margin is straighter and the body is widest at the anterior margin. This species also differs from T. licinum in having a more transversely elongate body; the vitelline follicles in the T. atkinsoni n. sp. do not extend along the anterior margin beyond the line of the cyclocoel, and the enclosed vitelline follicles are greater in number than those in T. licinum . The specimens of T. atkinsoni n. sp. from Ningaloo Reef are larger overall than those from Heron Island, however as the ITS2 sequences are identical; we attribute this difference to regional variation. Following examination of specimens of S. monogramma from Queensland Museum, previously attributed to T. licinum by Cribb et al. (1992) and in the light of data from this study those specimens are now recognized as T. atkinsoni n. sp. Transversotrema licinum specimens similar to T. atkinsoni n. sp. have not been found on any species of fish in Moreton Bay. The combination of overall body shape, distribution of the vitelline follicles in the anterior margin and the sizes of the ventral sucker, testes and ovary distinguish T. atkinsoni n. sp. from other species of Transversotrema and the morphological data is strongly supported by molecular results.

Figures

FIGURE 4. Transversotrema atkinsoni n. sp. ex Scolopsis monogramma Heron Island. Scale = 200 μm.