Imogine lateotentare, Lee & Beal & Johnston, 2006

Lee, Ka-Man, Beal, A. Michel & Johnston, Emma L., 2006, A new predatory flatworm (Platyhelminthes, Polycladida) from Botany Bay, New South Wales, Australia, Journal of Natural History 39 (47), pp. 3987-3995 : 3989-3993

publication ID	https://doi.org/ 10.1080/00222930500485263
persistent identifier	https://treatment.plazi.org/id/038A233B-5159-5355-F098-FB8CFC4EFE57
treatment provided by	Felipe
scientific name	Imogine lateotentare
status	sp. nov.

Treatment

Imogine lateotentare View in CoL sp. nov.

( Figures 1 View Figure 1 , 2 View Figure 2 )

Material examined

Holotype: W 29330, WM, 4 May 2004, Kurnell Pier , Botany Bay, New South Wales, Australia . Paratypes: W 29331, WM, 16 July 2004, Kurnell Pier , Botany Bay, New South Wales, Australia ; W 29332, LS, same data ; W 29333, S, same data .

Description

The size of flatworms measured live ranged from 9.5×4.7 to 19.2×8.0 (SE¡0.7×0.2) mm (n 515). Body rounded oval, thick and fleshy, blunt posterior, without marginal ruffles. Background of dorsal surface cream-beige (721) with scattered brown (731) mottling and light brown (722) flecking towards the margin ( Figure 1A View Figure 1 ). Purplish pink (507) flecks densely packed at the posterior of dorsal surface ( Figure 2A View Figure 2 ). Gonopores purplish red (216) at posterior end on ventral surface ( Figure 2B View Figure 2 ). Nuchal tentacles small and transparent, about 0.21 mm wide and 0.88 mm apart with 30–40 eyes aggregated at the tip of each nuchal tentacle. Four to five rows of scattered marginal eyes along the anterior margin, more densely packed anteriorly, reducing to two to three rows on both sides. Cerebral eyes numerous, embedded in the epidermis, aggregated in two bands lying between the tentacles, scattered to some distance to the back end of the tentacles, extending anteriorly into frontal eyes which are extremely numerous and scattered. Frontal eyes merge into anterior marginal eyes ( Figure 1C View Figure 1 ). Pharynx long, narrow and ruffled, in middle of body, three-quarters of body length, with about 22 complex pharyngeal folds. Mouth at two-thirds of pharynx ( Figure 1B View Figure 1 ). Intestinal branches are non-anastomosing. Gonopores close but well-separated posterior to pharynx. Female gonopore close and posterior to male pore. Vasa deferentia extend anteriorly from pores, originate laterally to pharynx, lying along the entire length of pharynx.

Testes scattered throughout body with tripartite globular seminal vesicle. Ventral, lateral and central lobes of seminal vesicle equally sized, about 0.5 mm long× 0.43 mm wide. Central lobe of seminal vesicle passes posteriorly, joins the prostatic duct at the proximal end of penis. Prostatic duct short joins dorsally to the mid-penis from prostatic organ. Prostatic organ large, muscular, about 0.78 mm long× 0.43 mm wide, horizontal to ejaculatory duct. Penis is simple, papilla small, within deep male antrum.

Ovaries scattered throughout the body. Vagina is long, muscular and narrow, with a shallow female antrum, accompanied by numerous cement glands ( Figure 1D View Figure 1 ). Life history is indirect through Gotte’s larva.

Diagnosis

Relatively small size compared to other Imogine spp. Cream-beige and light brown with irregular pattern of dark brown flecks over the dorsal surface and densely packed medially. Purplish pink flecks densely packed at the posterior of the dorsal surface and purplish red gonopores at the posterior of the ventral surface. Nuchal tentacles are not obvious.

Numerous and scattered cerebral and frontal eyes. Prostatic vesicle is relatively larger than seminal vesicle. Numerous cement glands.

Etymology

Named from the Latin, lateo 5hidden, tentare 5tentacles, for its inconspicuous and transparent nuchal tentacles.

Distribution

Imogine lateotentare was more common in spring and summer within emptied barnacle shells attached on the settlement plates deployed at Kurnell Pier. It also has been found associated with barnacles attached on the settlement plates at Port Kembla, New South Wales, Australia.

Biology

Egg deposition of I. lateotentare was observed in spring. Flatworms were observed to lay eggs within 5 days of solitary confinement in the laboratory (K.-M. Lee and E. L. Johnston, unpublished data). Thousands of eggs were deposited, mainly within empty barnacle shells and also in the corners of the container. The egg mass was white and opaque when first deposited, laid in zig-zag chains, covered with sticky gelatinous substance fastening the eggs firmly on the substrata. The egg mass became yellowish brown after 3–4 days. Hatching began 5–7 days after the eggs were laid. Gotte’s larva emerged, black in colour, with four ciliated lobes, anterior and posterior cilia tufts, and were positively phototatic. Emptied egg capsules remained on the substrata after hatching.

Ecology

Predatory behaviour and feeding rate. Size of opercula of B. variegatus recruits ranged between 4.5 and 7.6 mm, with a mean size of 5.5 mm (SE¡0.07). Length of flatworms ranged between 9.5 and 19.2 mm, with a mean length of 12.8 mm (SE¡1.4). Flatworms were observed to prey on B. variegatus exclusively at night. One B. variegatus was eaten in each of the six treatment replicates during the 2-week observation period. The flatworm was observed to glide across the barnacle to the opercular valves and to insert its pharynx between the tergum and scutum when the barnacle started to feed. The flatworm then stayed in that position for 15–30 min. The barnacle was observed trying to avoid the flatworm by closing or scraping its opercular valve around the edge of the opercular opening but that was not successful. The flatworm sucked out all the barnacle flesh using its pharynx, leaving the cirri untouched outside the shell. The flatworm then remained inside the dead barnacle shell for approximately 2–3 min. Dead barnacles eaten by Imogine were recognized by the presence of open unmoving opercular plates. White food particles showed up clearly in the gut of the worm. After feeding, the flatworm emerged from the empty barnacle shell and moved to a position beneath the settlement plate in the container. It remained there stationary for about 3 h, presumably in the process of digesting the barnacle. Thereafter, the flatworm recommenced activities, spending short periods of time moving around the container interspersed with longer periods of resting under the settlement plate.

The size of barnacle opercular openings did not differ between control and predation treatment containers (F 1,5852.8, P 50.10) and no barnacle died in the control containers. It is apparent that the replicate flatworms show similar behaviour. Flatworms spent approximately 80% of their time hiding underneath the settlement plate with occasional exploration of the container. Feeding was observed at night between days 6 and 8, with the flatworms staying underneath the plate with flesh seen in the gut for a few hours immediately after consumption. Further exploratory behaviour was observed for intermittent periods (2–4 days) after consumption of the barnacle.