Diamysis lacustris Băcescu, 1940

Wittmann, Karl J., Ariani, Antonio P. & Daneliya, Mikhail, 2016, The Mysidae (Crustacea: Peracarida: Mysida) in fresh and oligohaline waters of the Mediterranean. Taxonomy, biogeography, and bioinvasion, Zootaxa 4142 (1), pp. 1-70 : 28-29

Diamysis lacustris Băcescu, 1940

Fig. 13 D–H

Diamysis bahirensis: Spandl 1926 ; Holmquist 1955 (partim).

Diamysis bahirensis (?) mod. lacustris Băcescu 1940 (in footnote on p. 578).

Diamysis pengoi: Genovese 1956 (partim); Komarova 1991 (partim); Daneliya & Petryashev 2011 (partim). Diamysis bahirensis mod. lacustris: Ariani 1981b ; Wittmann & Stagl 1996.

Diamysis lacustris: Wittmann & Ariani 2012b ; Mees 2014.

Material examined. 3 samples from freshwater Lake Scutari (= Skadarsko jezero = Liqen i Shkodres), 42.23N 019.16E, see Wittmann & Ariani (2012b).

Diagnosis. Rostrum angular with narrowly rounded tip ( Fig. 13 E). Carapace without fringes in both sexes ( Fig. 13 D, F). Palpus of maxilla with subcircular terminal segment, armed with 10–16 denticles along distal margin. Males with spiniform outer corner of the basal segment in thoracic exopods 1–7 ( Fig. 13 D), this corner variable in exopod 8; females with this corner spiniform in exopod 1, subrectangular in exopods 2–7, or rounded in exopod 8. Thoracic endopod 3 with 3–2-segmented carpopropodus being longer than 5 times its maximum width ( Fig. 13 D); thoracic endopods 3–8 with long and slender claw. Penis with predominantly barbed setae on anterior face and in a semicircle close to the ejaculatory opening. Male pleopod 4 biramous with 2-segmented sympod, with small, 2-segmented endopod, and with moderately long, rod-like, 2-segmented exopod bearing a modified, strong seta at tip and a smaller, smooth seta subterminally on basal segment ( Fig. 13 G). Scutellum paracaudale triangular ( Fig. 13 D), with undulate margins ending in an acute tip. Endopod of uropod with one strong spine below large statocyst; statolith composed of vaterite. Telson subquadrangular ( Fig. 13 H), 0.7–0.8 times length of last abdominal somite; its apical cleft very shallow, only 7–12% telson length, cleft with almost straight margins forming an angle of 110–150°, cleft lined by 16–23 laminae.

Occurrence ( Fig. 12 ). Only known from the freshwater Lake Scutari at the SE-coast of the Adriatic Sea, altitude 5 m. The minimum distance of the lake to the sea is 43 km along its effluent or only 13 km as the crow flies.

Figures

FIGURE 12. Distribution of five species of Mysinae (Mysidae) in tributaries and coastal waters of the Adriatic Sea. In part modified from Wittmann & Ariani (2012 b).

FIGURE 13. Diamysis fluviatilis Wittmann & Ariani, 2012 (A – C), and D. lacustris Băcescu, 1940 (D – H). Materials from the Sile River (A – C) and Lake Scutari (D – H). A, cephalic region of female with body length 8.9 mm, dorsal; B, carapace expanded on slide, male 9.5 mm, dorsal; C, third pleopod of male 6.6 mm, rostral aspect; D, male with body length 5.2 mm, lateral view; E, cephalic region of female 8.0 mm, dorsal; F, carapace expanded on slide, dorsal, same male as in (D); G, fourth pleopod of same male, rostral; H, telson of same male, dorsal. B, F, pores on carapaces not to scale. From Wittmann & Ariani (2012 b).