Trigonostomum lilliei, (Graff, 1911)

Willems, Wim R., Artois, Tom J., Vermin, Wouter A. & Schockaert, Ernest R., 2004, Revision of Trigonostomum Schmidt, 1852 (Platyhelminthes, Typhloplanoida, Trigonostomidae) with the description of seven new species, Zoological Journal of the Linnean Society 141 (2), pp. 271-296 : 288-289

TRIGONOSTOMUM LILLIEI ( GRAFF, 1911A)

MEIXNER 1924B

( FIG. 7D )

Alternative species name: trigonostomum-lilliei

Woodsholia lilliei Graff, 1911b: 61–65 , fig. 3, t. IV, figs 29–43; 1913: 312–314, figs 277–279; Meixner, 1924b: 91, 92.

Trigonostomum prytherchi Kepner, Ferguson & Stirewalt, 1941: 243–252 , figs 1–3, pl. 3.

Trigonostomum divae Marcus, 1948: 121–125 , 189, t. III, figs 13–18.

Trigonostomum lilliei Meixner, 1924b: 92 , 94, 96, 99, 102.

Known distribution: North American Atlantic coast ( Graff, 1911b, 1913; Kepner et al., 1941), Brazil ( Marcus, 1948).

New locality: Australia, New South Wales, Arrawarra , rocky tidepool at low tide, on brown algae, 29 August 1996 ; south of the marine station, mideulittoral, on Sargassum sp., 1 November 1997.

Material examined: Observations on two live specimens, two whole mounts (all from Australia), the holotype of T. prytherchi , which is designated neotype (whole mount; SI-NMNH, Cat. no. 20593; Kepner et al., 1941) and Marcus’ (1948) material of T. divae (sections and whole mounts; SMNH, nos. 42204–8).

Diagnosis: Trigonostomum species with copulatory organ 42–46 Mm long. Stylet 40–57 Mm long, proximally bent over, 180∞. Mantle with one hooked plate (as long as the stylet) surrounds only the distal part of the stylet. Bursal appendage 95–98 Mm long, heavily coiled, consisting of one tube, which is distally split into five or six finer tubes.

Remarks and additional data: The stylet of the examined specimens is 40–57 Mm long (57 Mm in the holotype of T. prytherchi ; 40–43 Mm in Marcus’ material of T. divae , n = 2; 44–46 Mm in the Australian specimens, n = 2). The bursal appendage is a 95– 98 Mm long (n = 2). The bursal appendage could not accurately be measured in the second Australian specimen, or in Marcus’ material.

According to the description, including figures, of Kepner et al. (1941), it seems that they observed not one but three bursal appendages (including two smaller nonfunctioning appendages). These observations could be due to a misinterpretation of the serially sectioned material, because a thorough examination of the type material revealed only one bursal appendage.

According to Marcus’ (1948) drawings and description, the difference between T. divae and T. lilliei is the presence of only five tubes in the bursal appendage instead of six, a feature, which is often very difficult to assess. The overall construction of the bursal appendage of T. divae (i.e. the number and extent of coils) is identical to that of the Australian specimens. The bursal appendage of T. prytherchi is also identical in structure. The difference between T. prytherchi and T. lilliei would also be the ending of the prepharyngeal cavity in the ‘proboscis’ cavity as observed by Graff (1911b: fig. 31). According to Meixner (1924b) this feature is the result of the degree of contraction, and he therefore rejected the taxon Woodsholia . Because of these doubtful differences between these ‘species’ and the overall similarity in the structure of both the copulatory organ and the bursal appendage, we synonymise T. prytherchi and T. divae , with T. lilliei .

Figures

Figure 7. Copulatory organs and bursal appendages of the representatives of group 1B, A, T. coronatum: A1 copulatory organ; A2 bursal appendage. (from the neotype). B, T. watsoni sp. nov. B1, 2 copulatory organ; B3 bursal appendage (B1 from the holotype; B2, 3 from the paratype). C, T. penicillatum: C1 copulatory organ; C2 bursal appendage (from the neotype). D, T. lilliei: D1, 3 copulatory organ; D2, 4 bursal appendage. [D1, 2 specimen from Australia; D3, 4 specimen from the USA (neotype = holotype of T. prytherchi)]. E, T. breitfussi: E1 copulatory organ; E2 bursal appendage; E3 section through the bursa and the bursal appendage (different specimens from Sweden; E2, 3 freehand drawings). F, T. mirabile: F1, 2 copulatory organ; F3 bursal appendage (F1, 3 from the neotype; F2 from another specimen from the Black Sea). G, T. nataschae sp. nov. G1 Copulatory organ; G2 Bursal appendage (from the holotype).