Pontaralia Mack-Fira, 1968

Tokinova, Rimma P., Berdnik, Sergey V. & Ratushnyak, Anna A., 2011, First record of Pontaralia beklemichevi Mack-Fira, 1968 (Platyhelminthes: Rhabdocoela: Kalyptorhynchia) from the Russian Federation, Zootaxa 2973, pp. 66-68 : 66-68

Genus: Pontaralia Mack-Fira, 1968

Pontaralia beklemichevi Mack-Fira, 1968

Mack-Fira 1968: 333 – 341, pl. I – V; Mack-Fira 1974: 249,271,282,285; Evdonin 1977: 213 – 215, pic.53 З, 100 А,Б; Ax 2008: 466 – 468, abb.223A

Material. Eight specimens have been studied. Five whole specimens were embedded in gum-chloral liquid (Faure- Berlezet’s Fluid); three specimens were fixed in 70% ethanol.

Locality. The samples were collected on October 20 and 29, 2009 from the littoral zone of Lake Middle Kaban (55º44’29”N, 49º09’38”E) city of Kazan, Russian Federation. Both times, worms were found in thickets of reedmace ( Typha angustifolia ), at underwater snags covered with dense populations of Dreissena polymorpha (Pallas) .

Distribution. Republic of Romania, Lake Snagov (near Bucharest) and in the Razelm-Sinoë lagoon complex, Lake Golovitza ( Mack-Fira 1968, 1974).

Description. Length of the animal in motion was 1.4–1.5 mm, and about 1 mm in a contracted motionless state. Live specimens were colorless and transparent. The animals were elongated, with a narrow anterior part and a rounded caudal end ( Fig. 1 A).

The cirrus, which reaches 200 – 250 µm in length, forms the distal part (about two-thirds) of the male copulatory organ. The cirrus is provided with numerous spines ( Fig. 1 C), which might be separated into four groups based on their size and location.

In the first group, there are small and numerous spines located along the entire length of cirrus. These spines are 3 – 8 µm long, and the length increases from the proximal part to the distal part of cirrus. In the second group, there are four spines of 18 – 33 µm in length, located at the dorsal wall of the distal part of the cirrus. In the third group, the spines (numbering one to three) are located in the same place and have the size of 12 – 16 µm. In the fourth group, there are two very large spines of 58 – 75 µm in length, situated separately at the distal fold of cirrus.

The cocoon is oval-shaped with solid smooth surface of yellow-brown color. It is 175x240 µm in size, with a stalk 10 µm long ( Fig. 1 B).

Basically, the external and internal structure of worms from Lake Middle Kaban ( Fig. 1 D) fits the description of worms from Lake Snagov as provided by Mack-Fira (Mack-Fira 1968). However, comparative analysis of internal morphological structures revealed substantial differences in the sizes of cirrus spines ( Table 1). We have found that spines in the cirrus are larger in worms from Middle Kaban Lake than those in the Romanian worms.

Discussion. According to the recent data ( Korgina 2005) the turbellarian fauna of the Volga basin includes 116 species, belonging to 7 orders and 16 families, but only one species of Koinocystididae Meixner, 1924 - Koinocystis neocomensis (Fuhrmann) - has been found here. P. beklemichevi is a relict of the Ponto-Aral-Caspian basin ( Mack-Fira 1968, 1974). The genus Pontaralia includes one more relict species - Pontaralia relicta ( Beklemischev, 1927) , which is a typical brackish water species found in the former Aral Sea ( Beklemischev 1927), the Caspian Sea (city of Lenkoran) (Beklemischev 1953), and the Black Sea, the Razelm-Sinoë lagoon complex ( Mack-Fira 1974).

Group 2 16–22 18 –33

Group 3 9 12 –16

Group 4 51–59 58–75

The presence of the Ponto-Aral-Caspian relict in the basin of the Middle Volga, far from its type locality, is remarkable. Lake Kaban is a bayou of an ancient Volga creek, separated from the main riverbed 10 – 75 thousand years ago ( Mingazova & Kotov 1989). A wide communication between Lake Kaban and the Volga persisted for a long time up to the early 20th century. Nowadays, the communication of the lake with the Volga (the Kuibyshev reservoir) continues, though severely limited. It is probable that P. beklemichevi migrated from the Black Sea basin via the Black Sea-Volga- Caspian Sea transit way first into the Volga and Kuibyshev reservoir, and from there into Lake Kaban. The Ponto-Aral- Caspian fauna complex is widely represented in the fauna of Kuibyshev reservoir. The process of invasion of Lake Kaban and Middle Volga basin by alien species from the Ponto-Caspian basin is still continuing at present. Mollusks, annelids and crustaceans are among these immigrants ( Yakovleva et al. 2009). Consequently, turbellarians are not an exception and P. beklemichevi can be added to the list of modern Ponto-Caspian invaders in Lake Middle Kaban and the Middle Volga basin.

Figures

FIGURE 1. Pontaralia beklemichevi A, Dorsal view of live animal. B, Cocoon. C, Cirrus (from a whole mount). D, General organization of live animal. bs, female bursa; c, cirrus; e, eye; fd, female duct; ga, common genital atrium; gr 1 – gr 4, groups of cirrus spines; ov, ovary; ph, pharynx; pr, proboscis; t, testis; ut, uterus; vi, vitellarium; vs, seminal vesicle.