Transversotrema

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 : 33-34

Transversotrema nova n. sp.

( Fig. 12 )

Type-host: Nemipteridae : Scolopsis bilineatus (Bloch) Two-lined monocle bream

Type-locality: New Caledonia (21°30’S 165°30’E).

Site: Beneath the scales

Material examined: No prevalence data is available for this species. The specimens were discovered late in the study.

Deposited specimens: Holotype: QM G231899 (ex Scolopsis bilineatus NC coll. Cribb

Etymology: This species was found from nemipterid fishes from New Caledonia. The name nova reflects in part the name of its locality, its recent description and the fact that it is a new transversotrematid species from the region.

Description: Based on measurements of 2 specimens from nemipterids from New Caledonia. Body transversely elongated, strongly dorsoventrally flattened, 513–634 (574) long, 1373–1859 (1616) wide; average width/ length range 2.8:1. Pharynx to anterior margin 167–189 (178). Cyclocoel to posterior margin 89–125 (107). Anterior margin straight, body D–shaped. Tegumental spines prominent in offset rows. Eyespots prominent, 132–163 (148) apart, 9% of body width; positioned beside anterior margin of pharynx; no pigment evident other than in eyespots. Ventral sucker well posterior to eyespots, 2,878–3,592 (3,235) μm2. Mouth mid-ventral, inconspicuous. Pharynx between eyespots, 91–96 (93) long, 86–93 (89) wide. Oesophagus curved 66–88 (78) 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, 10,255–15,005 (12,630) μm2; right 6,983–11,449 (9,241) 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, five prominent extended lobes, 10,419–11,387 (10,903) μm2. Oviduct passes medio-posteriorly, unites with Laurer’s canal and duct from oviduct passes vitelline reservoir, Laurer’s canal 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 dense in rows of three or four. Enclosed follicles in two loosely assembled masses at each lateral extremity, 23–26 (24) no follicles 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 102–143 (122.5) long, 41–48 (44.5) wide, few in utero 0–2 (2). 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 nova n. sp. is D–shaped, unlike T. licinum which is crescent–shaped, it has a straighter anterior margin and the body is widest at the anterior margin. This species also differs from T. atkinsoni n. sp. from Heron Island nemipterids which has a more transversely elongate body and the vitelline follicles of T. nova n. sp. do not extend beyond the line of the cyclocoel. Enclosed vitelline follicles are fewer in number than those in T. atkinsoni n. sp. A distinguishing character of T. nova n. sp. is the size of the ovary which is very large compared to the area of the testes and the average area of the ovaries is larger than that of the right testis. This character is seen otherwise only in T. damsella n. sp. which is found from pomacentrids from Lizard Island. There is no molecular material available of the specimens from the four mugilid host species mentioned in Cribb et al. (1992), however, from the combined data from this study, molecular, morphometric and morphological, we conclude that new species status should be given to this form. Although there is one sequence from a Chaetodon flavirostris from New Caledonia which reveals that it is distinguished by molecules from T. borboleta n. sp. from chaetodontids at Lizard Island, we think it is highly improbable that it is the same species as T. nova n. sp. There are no data to show that transversotrematids from nemipterids and chaetodontids are conspecific. Transversotrematids from nemipterids from Lizard Island and Heron Island are mutually exclusive in both their morphology and genetics, and transversotrematids from nemipterids and chaetodontids from Lizard Island are likewise separated morphologically and genetically. Transversotrema nova n. sp. is easily distinguishable morphologically from T. atkinsoni n. sp. and T. carmenae n. sp. Nemipterids from such distant locations as Heron Island and Ningaloo have been reported as host of morphologically similar and molecularly (ITS2) identica l T. atkinsoni n. sp. specimens. Transversotrema carmenae n. sp. from Lizard Island nemipterids is morphologically more similar than is T. atkinsoni n. sp. to T. nova n. sp. however they are notably different in testes and ovary dimensions and in the density and distribution of the vitelline follicles in the margins. 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. nova n. sp. from other species of Transversotrema . There are three distinct species from nemipterids, all from different locations. Molecular data supports the distinction of T. carmenae n. sp. and T. witenbergi n. sp. which are also morphologically distinct. Although there are no molecular data for T. nova n. sp. it is easily distinguishable from both of these species by its morphology.

Figures

FIGURE 12. Transversotrema nova n. sp. ex Scolopsis bilineatus New Caledonia. Scale = 200 μm.