Diamysis fluviatilis Wittmann & Ariani, 2012

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

Diamysis fluviatilis Wittmann & Ariani, 2012

Fig. 13 A–C

Mysis oculata relicta: Stammer 1932 (partim).

Diamysis bahirensis: Holmquist 1955 ; Minelli & Trevisanello 1985. Diamysis bahirensis ssp.: Ariani 1981b (partim).

Diamysis mesohalobia: Cibinetto et al. 2006 .

Diamysis mesohalobia heterandra: Corazza et al. 2010 .

Diamysis fluviatilis Wittmann & Ariani 2012b : Mees 2014; Wittmann et al. 2014.

Material examined. 23 samples from freshwater tributaries of the North Adriatic Sea , see Wittmann & Ariani (2012b). Additional materials are from the lower Timavo system, 45.79N 013.58E, Gulf of Trieste, NE-Adriatic: 4 slides labelled " Diamysis biharensis . Herzegovina & Timavo. Det . Ch. Holmquist, prep. 60–63"; the data given by Stammer (1932) and Holmquist (1955: Tab. 1) suggest that this material was collected in 1928/29 by Hans Jürgen Stammer in waters of the Timavo system: prep. nos. 60, 61 ( SMNH reg. nos. 140111, 140112) are dissected parts of 1 M ad. 8.5 mm and of 1 F ad. 9.5 mm with nauplioid larvae from former fresh-waters in the meadows (now industrial port zone) between the Timavo estuary and the Monfalcone creek , 45.789N 013.581E; prep. nos. 62, 63 ( SMNH reg. nos. 140113, 140114) are parts of 1 M ad. 8.5 mm and of 1 F ad. 8.5 mm with nauplioid larvae from still existing springs of the Monfalcone creek , 45.7984N 013.5701E.

Diagnosis. Rostrum well rounded or forming a wide convex angle with broadly rounded tip ( Fig. 13 A). Male carapace with fringes arranged in two submedian stripes ( Fig. 13 B), no such fringes in females. Palpus of maxilla with subcircular terminal segment, armed with 9–19 denticles along distal margin. Basal segment of thoracic exopods 1–8 in males and exopods 1–3 in females with spiniform outer corner (as in Fig. 14 D); this corner variable in exopods 4–8 of females. Thoracic endopod 3 with 3-segmented carpopropodus being longer than 5 times its maximum width; thoracic endopods 3–8 with long and slender claw. Penis with smooth setae only. Male pleopod 4 biramous with 2-segmented sympod, with small, 1–2-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 the basal segment (as in Fig. 13 G). Scutellum paracaudale well rounded to apically pointed, margins not or inconspicuously undulate. Endopod of uropod with one strong spine below large statocyst; statolith composed of vaterite. Telson subquadrangular, 0.7–0.9 times length of last abdominal somite; its apical cleft with slightly to strongly convex margins. Bottom of cleft concave, rounded. Cleft is 9–17% telson length, cleft lined by 15–48 laminae.

Distribution ( Fig. 12 ). In wells, springs, tributaries, canals, main courses, and estuaries of rivers flowing to the NE to NW coasts of the Adriatic Sea (Reno, Po, Mincio, Adige, Brenta, Sile, Livenza, Lemene, and Isonzo), including the Timavo system. Maximum observed sea distance 182 km, maximum altitude 16 m. Mostly in freshwater, also oligohaline; only in the lower Timavo estuary observed down to the mesohaline reach (S = 2–13).

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).

FIGURE 14. Diamysis mesohalobia mesohalobia Ariani & Wittmann, 2000, paratypes from the brackish spring Fiume Morello at the Adriatic coast of SE-Italy. A, dorsal aspect of male with body length 6.5 mm; B, antennula of male 6.3 mm, dorsal; C, carapace expanded on slide, male 6.0 mm, dorsal; D, exopod of first thoracopod, male 6.3 mm, caudal aspect; E, tarsus (i. e. carpopropodus plus dactylus) of fourth thoracic endopod, male 6.4 mm, rostral; F, right face of left penis, male 6.3 mm; G, third pleopod of same male, rostral; H, fourth pleopod of same male, rostral; J – M, posterior margin of sixth pleonite, lateral, in female 6.6 mm (J), female 6.8 mm (K), and two males, each with 6.3 mm (L, M); N, telson of male 6.3 mm, dorsal. A, C, pores on carapaces not to scale. A, B, D, E, G – N, modified from Ariani & Wittmann (2000); C, F, original.