Diamysis mesohalobia heterandra Ariani & Wittmann, 2000

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 : 33-36

Diamysis mesohalobia heterandra Ariani & Wittmann, 2000

Fig. 15 K–S

Mysis oculata var. relicta: Zimmer 1927 (partim: Lake Deran). Diamysis bahirensis: Holmquist 1955 ; Avĉin et al. 1973 (partim); Matjašič & Štirn 1975 (partim); Ariani et al. 1983, 1993 (partim).

Diamysis bahirensis ssp.: Ariani 1981b (partim).

Diamysis sp.: Wittmann & Stagl 1996 (partim).

Diamysis mesohalobia heterandra Ariani & Wittmann, 2000: 2004, 2005 ; Anderson 2008; San Vicente 2010; Wittmann & Ariani 2010, 2012a, 2012b; Mees 2014.

Material examined. 42 samples from oligohaline to metahaline lagoons and karstic springs in diverse parts of the eastern Mediterranean plus 13 samples from freshwater tributaries of the Adriatic Sea, see Ariani & Wittmann (2000) and Wittmann & Ariani (2012b); material studied by Holmquist (1955), previously unpublished reexamination: dissected parts of 1 M ad. 8 mm, 2 egged F ad. with body length 7 or 9 mm, respectively, on a total of 3 slides labelled " Diamysis biharensis . Herzegovina & Timavo, det . Ch. Holmquist, prep. 57–59", SMNH reg. nos. 140108 – 140110. According to Holmquist (1955) this material was collected by Janez Hoenigman in Lake Deran , 2–5 m depth , 27 Apr. 1954, 43.04N 017.75E, Herzegovina, altitude 0 m, sea distance 31 km as calculated along the small effluent and following this along the Neretva River to the east coast of the Adriatic Sea.

Short updated description. The following data covers primarily the type population in an oligo- to mixoeuhaline lagoon with brackish spring, Limni Antinioti ( Island of Corfu , Ionian Sea). Data from remaining populations, as far as different, are given in square brackets.

Diamysis mesohalobia with short rostrum mostly forming a wide convex angle with broadly rounded tip ( Fig. 15 K, L). Fenestra paracornealis weakly developed, mostly visible ( Fig. 15 K) in well preserved material [mostly visible in well preserved material from Lake Deran (near E-Adriatic coast) or rarely from Schiavetti Springs (Gulf of Trieste, N-Adriatic)]. Carapace of adult males with fringes arranged in two submedian stripes plus one subterminal stripe ( Fig. 15 K, L). The submedian stripes may be differentiated as two separate stripes each ( Fig. 15 K). Palpus of maxilla with subcircular terminal segment, armed with 8–27 denticles along distal margin. Basal segment of all thoracic exopods normally with spiniform outer corner, rounded only in some of the posterior exopods of small individuals (<6 mm). Pereiopods of intermediate length, endopod 8, when stretched anteriorly, extending to maxillae or at most to labrum. Pereiopods stout to slender, with R6 = 4.5–6.7 [4.5–7.9]. Carpopropodus of thoracic endopods 3–8 with 3, 3 (2), 2–3, 2 (3), 2, and 3–2 segments, respectively [3, 3–2 (4), 2– 3, 2–3, 2–3, and 3–2]. Thoracic endopod 3 with carpopropodus longer than 5 times its maximum width ( Fig. 15 M); thoracic endopods 3–8 with long and slender claw. Penis with smooth setae only, arranged in a semicircle close to ejaculatory opening. Male pleopod 4 biramous with 2-segmented exopod; apical segment with a modified, strong seta at tip and in large males (> 6 mm) often with a minute additional seta; basal segment subterminally with a smooth seta ( Fig. 15 N–P). Large males (> 7 mm) with 0–1 [0–4] additional small barbed [and/or smooth] seta ( Fig. 15 N, P) on terminal margin of basal segment of exopod. Scutellum paracaudale subtriangular, mostly biconvex [or with upper margin convex and lower margin concave]; tip pointed ( Fig. 15 Q, R) or less frequently rounded, rarely bifid. These margins mainly smooth in small specimens [or undulate in large ones (> 8 mm; Fig. 15 Q)]. Telson mostly subquadrangular ( Fig. 15 S), but subtriangular in small specimens (<6 mm), 0.7–0.9 [0.7–1.0] times length of last abdominal somite; lateral margins concave [to straight], armed with 8–13 [6–11] spines; maximum width of telson is 1.8–2.4 [1.4–2.4] times that at apex; its apical cleft with straight to strongly convex margins. Bottom of cleft angular to rounded. Cleft is 10–19% [10–26%] telson length, cleft lined by 12–31 [9–38] laminae ( Fig. 15 S).

Body length. Adult females 3.7–9.7 mm, males 3.0– 8.7 mm.

Distribution ( Figs 12 , 16 ). In fresh and brackish waters of springs, estuaries, lagoons, and lakes all around the Adriatic Sea ( Fig. 12 ), salinity range S = 0–42. Outside the Adriatic ( Fig. 16 ) known only from oligo- to polyhaline waters on the coasts of the Ionian and Marmora Seas, so far not from fresh-water (Ariani & Wittmann 2000, Wittmann & Ariani 2012a, b).

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 15. Diamysis mesohalobia gracilipes Ariani & Wittmann, 2000 (A – J), and Diamysis mesohalobia heterandra Ariani & Wittmann, 2000 (K – S). Materials from Mar Piccolo in the Gulf of Tarent (paratypes: A – E, G – J, Ionian Sea), the Bay of Strunjan (F, Gulf of Trieste, NE-Adriatic Sea), Lake Deran (L, N, P – S, E-Adriatic), Limni Antinioti (K, M, Island of Corfu, Ionian Sea), and Lakes of Bacin (O, E-Adriatic). A, anterior body region of male with body length 7.2 mm, dorsal view on cephalothorax; B, tarsus (i. e. carpopropodus plus dactylus) of third thoracopod, male 6.5 mm, rostral; C, left face of right penis, male 7.2 mm; D, E, exopod of fourth pleopod, rostral, in males with 4.4 mm (D) or 6.5 mm (E) body length; F – H, posterior margins of sixth pleonite in female with 7.4 mm (F), in male with 7.2 mm (G), and in female with 4.8 mm (H) body length, lateral; J, telson of male 7.2 mm, dorsal; K, anterior body region of male 5.2 mm (paratype); L, carapace expanded on slide, dorsal, male 7.9 mm; M, tarsus of third thoracic endopod, rostral, male 5.2 mm (paratype); N, fourth pleopod of male 7.9 mm, rostral; O, P, exopod of fourth pleopod, rostral, in males with 5.5 mm (O) or 8.4 mm (P) body length; Q, R, posterior margins of sixth pleonite in female with 9.8 mm (Q) or in male with 6.0 mm (R) body length, lateral; S, telson of male 7.9 mm, dorsal. A, K, L, pores on carapaces not to scale. A, D, E, G – K, M, modified from Ariani & Wittmann (2000); L, N – S, modified from Wittmann & Ariani (2012 b); B, C, F, original.

FIGURE 16. Distribution of Limnomysis benedeni Czerniavsky, 1882, Neomysis integer (Leach, 1814), and the three subspecies of Diamysis mesohalobia Ariani & Wittmann, 2000, in tributaries and coastal waters of the Mediterranean and adjacent seas. Data original and from 79 literature sources.