Paratya compressa

Marin, Ivan, 2018, On the taxonomic status of amphidromous shrimp Paratya borealis Volk, 1938 (Crustacea: Decapoda: Atyidae) from the south of the Russian Far East, Zootaxa 4444 (2), pp. 154-162 : 156-159

Paratya compressa (De Haan, 1844 [in De Haan, 1833 -1850])

( Figs. 1 , 2 )

? Ephyra compressa De Haan, 1844: 186 , pl. 46 [type locality: Japan].

Miersia compressa: Kingsley 1879: 416 .

Xiphocaris compressa: Doflein 1902: 631 .

Xiphocaridina compressa: Bouvier 1909a: 330 (part); 1909b: 328 (part).

Paratya compressa: Roux 1926: 238 ; Kubo 1938: 68, figs. 2A, 3A–E; 1941: 127.

Paratya borealis Volk, 1938: 123 , Figs 1 -4 [type locality: Russia, Uluncha River ].

Paratya compressa compressa: Shokita 1975: 119 ; 1990: 311; Hayashi 1989: 498, figs. a–f; Yamaguchi & Baba 1993: 215, fig.36; Page et al. 2005: 584.

Not Paratya compressa: Kemp 1917: 294 , fig.1; 1918: 293.

Material examined. Russian Federation, Far East, Primorye: 2 males ( LEMMI), Andreevka River (=Uluncha River) flowing into Troiza Bay (part of Posyeta Bay), the Sea of Japan, 42°38'56.8"N 131°08'15.8"E, collected with hand net on water grass into a river stream, coll. I. Marin, June 2009; 3 non-ovigerous females, 3 males ( ZMMU Ma3575), Volchanka River flowing into Vostok Bay (part of the Peter the Great Bay), the Sea of Japan), 42°55'11.8"N 132°41'45.6"E, collected with hand net on water grass into a river stream, coll. I. Marin, July 2017; 3 non-ovigerous females, 3males ( LEMMI), Razanovka river flowing into Boysmana Bay (part of the Peter the Great Bay), the Sea of Japan, 42°46'34.7"N 131°15'33.9"E, collected with hand, unknown collector, without date.

Taxonomic remarks. All examined shrimps are mostly identical to the original description of P. borealis given by Volk (1938) and very similar in morphology to P. comPressa described by Kemp (1917), Kubo (1938), Hayashi (1989) and Cai & Shokita (2010). Rostrum ( Fig. 1 a–d ) almost straight with tip slightly turned upward, overreaching distal margin of scaphocerite, ventral margin convex in females ( Fig. 1 a, b ) and nearly horizontal in males ( Fig. 1 c, d ), rostral formula—2–3+20–27/2–4; antennal spine well marked; pterygostomian margin subrectangular. Telson ( Fig. 1 g, h ) about 4 times as long as wide, not terminating in a posteromedian projection, with two pairs of dorsal submarginal spines situated at 0.5 and 0.75 of the length; distal margin, armed with 5 pairs of spines, with sublateral pair longer than intermediates spines. Third pereiopod reaching to the end of scaphocerite, propodus about 10–11 times as long as broad; dactylus about twice as long as wide, terminating in one large distal spine and 5–6 accessory spines on flexor margin ( Fig. 1 e, f ).

Minor morphological differences are found in rostral armature—specimens from Russia have slightly more dorsal teeth than specimens from Japan (after Kubo, 1938; Cai & Shokita, 2010). At the same time, armature of dactylus of pereiopod III described by Kemp (1917) differs from both Russian and specimens described from south Japan by Kubo (1938) and Cai & Shokita (2010) possibly showing the cryptic forms within P. comPressa from southern Japan. Such cryptic diversity (for example, between specimens from Kyushu and Okinawa) is indirectly confirmed by the genetic comparison of COI mtDNA (see Fig. 3 ).

One more Asian Paratya species, Paratya boninensis Satake & Cai, 2005 , is known from Ogasawara (Bonin) Islands ( Satake & Cai, 2005) (see Fig. 3 ). The morphology of the species is somewhat similar to P. comPressa , for example rostrum and dactyli (Satake & Cai, 2 005: 1A, 2E), but DNA data of this species is not available for the comparison. The species must be considered in the further researches of Paratya shrimps occurring in the studied area.

Alive coloration. The coloration of studied specimens ( Fig. 2 ) is very similar to P. comPressa from southern Japan. The body is mostly yellowish of transparent, scaphocerites, carapace, abdominal segments, telson and uropods covered with stripes of yellow, red and brown chromatophores; broad yellow dorsal longitudinal band on carapace, abdomen and telson as well as poorly-defined transverse brown bands on abdomen present in large ovigerous females ( Fig. 2 ); smaller shrimps are more transparent. Eyes are yellow or brown-goldish. Pereiopods mostly transparent, with bands of yellow, red and brown chromatophores on segments.

Size. Studied specimens belong to relatively large freshwater caridean shrimps. Carapace length reaching 14.0 mm and total length about 40 mm in males. Females are significantly larger—carapace length reaching 18.0 mm and total length about 52 mm.

Ecology. Although the biology of Paratya shrimps (feeding, brood and life cycles) from the studied are is completely unstudied, it is known that the species is amphidromous; larvae require increased salinity to complete their development (e.g. Vinogradov, 1950; Vasilenko & Starobogatov, 1995; Marin, 2013; Marin & Kornienko, 2014; Fujita et al., 2016). Mature specimens of P. comPressa were found in rivers flowing into the Sea of Japan about 2–3 kilometers far from the sea and river estuary (data similar to Ikeda, 1999). Shrimps were observed sitting on water grass, algae bunch or hide under clusters of flooded branches and snags preferring places with a moderate current.

Distribution. The species is known along mainland coast of the Sea of Japan from the most northern known locality at 42°55'11.8"N 132°41'45.6"E then probably along the Korean Peninsula coast to Busan and further to Tsushima Island and southern Japanese Islands - southern Honsu, Shikoku, Kyushu Islands, and Okinawa ( Fig. 3 ) ( Kemp, 1917; Volk, 1938; Kubo, 1938; Lee, 1958; Yamaguchi & Baba, 1993; Ikeda, 1999; Cai & Shokita, 2010). Distribution of the species in central part of Honsu Islands, where misidentified with relative species, Paratya imProvisa Kemp, 1917 , is described by Ikeda (1999). Nevertheless, the investigation greatly increases the area of distribution of P. comPressa for more than 1000 km to north and suggests that this species could also inhabit rivers flowing into the Sea of Japan along North and South Korean coasts (e.g. Kemp, 1917 (Busan and Tsushima Island); Lee, 1958 (Nam-hae Island)) ( Fig. 3 ).

Presently, the list of Decapoda species known from Vostok Bay of the Sea of Japan includes 65 species belonging to 22 families, including some recently described species ( Anker et al., 2016; Marin, 2010, 2013b, c, 2015, 2016, 2017; Marin & Kornienko, 2014; Marin et al., 2011, 2012, 2013, 2018), and seems to describe the fauna of the region rather well. At the same time, the current decapod species list include a number of species early identified by the analogy with widely distributed species and their taxonomic status need to be clarified using the modern taxonomic methods, for example, DNA analysis (e.g. Marin et al., 2018).

Figures

FIGURE 1. Paratya compressa (De Haan, 1844) from Razanocka (LEMMI) (a, c, f, g) and Volchanka (ZMMU Ma3575) (b, d, e, h) rivers flowing into the Peter the Great Bay of the Sea of Japan, females (a, b, g), males (c–f, h): a–d—front of carapace, dorsal view; e, f—dactylus of pereiopods III; g, h—telson.

FIGURE 2. Alive coloration of Paratya compressa (De Haan, 1844) from Volchanka river (ZMMU Ma3575) (the Peter the Great Bay of the Sea of Japan): (a, c–e) female, (b, f) male.

FIGURE 3. The map of records and probable area of distribution of Paratya in northern Asia. For P. compressa records from South Korea are indicated only (after Kemp, 1917; Lee, 1958); for Japanese records see Ikeda (1999).