Phagocata gallaeciae Vila-Farré & Sluys, 2011

Vila-Farré, Miquel, Sluys, Ronald, Almagro, Ío, Handberg-Thorsager, Mette & Romero, Rafael, 2011, Freshwater planarians (Platyhelminthes, Tricladida) from the Iberian Peninsula and Greece: diversity and notes on ecology, Zootaxa 2779, pp. 1-38 : 18-20

Phagocata gallaeciae Vila-Farré & Sluys , sp. nov.

( Table 1 , Figs. 3 , 11 A–D)

Material examined. HOLOTYPE. ZMA V.Pl. 6870.1, River Miño, Ourense city, Spain, 21 November 2004, sagittal sections on three slides.

Other material. ZMA V.Pl. 6871.1, River Miño, Ourense city, Spain, 30 May 2004, sagittal section on four slides; V.Pl. 6871.2, ibid., sagittal section on three slides; V.Pl. 6871.3, sagittal section on five slides; V.Pl. 6871.4, sagittal section on three slides; V.Pl. 6872.1, River Miño under the dam of Belesar, Chantada, Lugo, Spain, February 2007, sagittal sections on four slides; V.Pl. 6872.2, ibid., sagittal section on two slides; V.Pl. 6872.3, ibid., sagittal section on two slides; V.Pl. 6872.4, ibid., sagittal section on two slides; V.Pl. 6872.5, ibid., sagittal section on three slides; V.Pl. 6872.6, ibid., sagittal section on three slides.

Ecology. Although the areas of Galicia and Asturias in northwestern Spain have been prospected by the authors, Ph. gallaeciae has only been found in the river Miño (Galicia), a large river in which the species can be very abundant locally. Specimens were collected from under stones. On one occasion, we made an abundant collection of only asexual specimens in the city of Ourense.

Etymology. The specific epithet is derived from the Latin word Gallaecia, the region of Galicia in the northwestern part of the Iberian Peninsula. The specimens were collected from this region.

Diagnosis. Phagocata gallaeciae sp. nov. is characterized by vasa deferentia that enter the penis bulb after having followed a recurved loop of varying lengths in each of the spem ducts; the oblique orientation of the cylindrical penis papilla, and a rather small and weak penis bulb.

Description. Preserved specimens measure up to 6 x 1.5 mm. In living specimens, the dorsal surface is pigmented dark or light brown ( Fig. 11 A), with a pigment-free body margin in some animals. The head is truncated, with slightly rounded lateral projections or auricles and a very small protrusion in the medial portion of the frontal margin. Live, active animals show an indistinct “neck” region at the level of the eyes. The hind end of the body is pointed.

The small eyes (diameter of the pigment cup 30 µm in V.Pl. 6871.2 and 28–36 µm in V.Pl. 6870.1) are set in pigment-free patches that are located far from the frontal margin and lie close together. The number of retinal cells in each pigment cup could not be determined with certainty.

The cylindrical pharynx is situated in the middle of the body and measures about 1/6th of the body length. The outer epithelium of the pharynx is underlain by a layer of longitudinal muscle fibres, followed by a layer of circular muscles. The inner epithelium is underlain by a thick layer of circular muscles, followed by a layer of longitudinal muscle fibres. The mouth is situated in the posterior portion of the pharyngeal pocket. In specimen V.Pl. 6870.1, the mouth is situated 2.45 mm from the anterior end of the body and 270 µm from the gonopore, as measured from histological sections.

The medium-sized testes are densely packed together and extend from the level of the ovaries into the posterior end of the body. They occupy about 1/3rd of the dorsoventral diameter of the body. Although the follicles are situated ventrally, some may extend dorsally to just beyond the midline.

At the level of the penis papilla, one of the vasa deferentia curves dorsally, ascending to almost the dorsal epidermis in some specimens (V.Pl. 6872.1). It then performs a backward loop and penetrates the dorsal wall of the penis bulb ( Fig. 11 B). However, the other sperm duct enters the penis bulb through its base, after having followed a much smaller recurved loop. At the base of the penis papilla the vasa deferentia fuse to form a wide ejaculatory duct that is lined with tall, nucleated epithelium, which is underlain by a thin layer of circular fibres. In specimen V.Pl. 6870.1 and V.Pl. 6871.2, the ejaculatory duct runs centrally through the penis papilla ( Fig. 11 B, C). In contrast, in specimen V.Pl. 6871.4 the distal portion of the ejaculatory duct is curved towards the ventral side of the penis papilla and has a slightly subterminal opening, most likely due to preservation artefacts ( Fig. 11 D). The cylindrical penis papilla has an oblique orientation. The epithelium of the papilla is underlain by a layer of circular muscle fibres, followed by a layer of longitudinal muscle fibres. The rather small and weak penis bulb is formed by intermingled longitudinal and circular muscle fibres. The male atrium is covered with a layer of circular muscle fibres, followed by a layer of longitudinal fibres. The lining epithelium of the male atrium is considerably thicker on the dorsal section than it is on the ventral part.

The ovaries are located a short distance behind the brain and occupy about 1/3rd of the dorsoventral diameter of the body. The oviducts arise from the lateral surface of the ovarial wall, run backwards dorsally to the ventral nerve cords and curve mediodorsally at the level of the gonopore. Thereafter, the oviducts unite to form a vertical common oviduct, which receives the openings of a few shell glands in its central section. This common oviduct opens through the posterior wall of the male atrium. The curved bursal canal runs from the bursa dorsally to the male atrium and opens into the small common atrium. The lining epithelium of the wide (especially at its central section) bursal canal consists of nucleated cells. The canal is surrounded by a subepithelial layer of circular muscle fibres, followed by a layer of longitudinal muscle fibres, the latter being thicker on the ventral side of the bursal canal. The size of the copulatory bursa varies between specimens ( Fig. 11 B, D). The sac-shaped copulatory bursa occupies almost the entire dorsoventral diameter of the body in specimen V.Pl. 6871.4, whereas it is much smaller in specimen V.Pl. 6870.1.

Discussion. The gross morphology of the copulatory apparatus of Ph. gallaeciae resembles that of a large number of species of the genus Phagocata s. s. We will restrict our comparisons to pigmented species.

Differences between the following species and Ph. gallaeciae are the same as those presented in the discussion on Ph. asymmetrica and therefore will not be repeated here: Ph. armeniaca , Ph. bulbosa , Ph. crenophila , Ph. fawcetti , Ph. fontinalis , Ph. gracilis , Ph. iwamai , Ph. kawakatsui , Ph. maculata , Ph. miyadii , Ph. nordeni , Ph. papillifera , Ph. sibirica , Ph. suginoi , Ph. teshirogii , Ph. uenoi , Ph. ullala , Ph. velata , Ph. vernalis , Ph. virilis , Ph. vivida and Ph. woodworthi .

Two pigmented species remain to be discussed: Ph. tahoena from North-America and Ph. asymmetrica . The epithelium of the bursal canal is very tall and the penis bulb very large in Ph. tahoena , whereas the epithelium is less tall and the penis bulb smaller in Ph. gallaeciae .

Each vas deferens in Ph. asymmetrica follows a different course and when they fuse after having penetrated the penis bulb, the ducts go in opposite directions. In contrast, each vas deferens in Ph. gallaeciae follows a different course, but both show a marked loop (of different extent) and when they fuse after having penetrated the penis bulb the ducts do not go in opposite directions. In addition, the vasa deferentia in Ph. asymmetrica fuse just before opening into an intrabulbar cavity, while the ejaculatory duct receives the secretion of two types of glands. In contrast, there is no intrabulbar cavity in Ph. gallaeciae .

Figures

FIGURE 3. Distributional records of twelve species of freshwater planarians in the Iberian Peninsula. Data from De Beauchamp, 1920; De Beauchamp, 1932; Baguñà et al. 1980, 81; Gourbault, 1981; Ribas, 1990; Sluys et al. 1995; Carranza & Giribet, 1997; unpublished records, this study.

FIGURE 11. Phagocata gallaeciae (A) specimen from the River Miño after Belesar dam, living animal, (B – C) holotype, V. Pl. 6870.1, (B) sagittal reconstruction of the copulatory apparatus (anterior to the left), (C) sagittal section of the copulatory apparatus (anterior to the left), (D) V. Pl. 6871.2, sagittal reconstruction of the copulatory apparatus (anterior to the left).