Paramysis (Longidentia) adriatica, Wittmann, Karl J., Ariani, Antonio P. & Daneliya, Mikhail, 2016

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 : 19-26

Paramysis (Longidentia) adriatica sp. nov.

Figs 7 A, B, 8–10, 11A

Mysis oculata relicta: Stammer 1932 (partim: station Tb9 ").

Paramysis helleri: Holmquist 1955 ; Ariani et al. 1993: Tab. I (partim: Split); Ariani 2004: fig. 3B.

Type material. Holotype male with 9.1 mm body length ( NHMW reg. no. 25694), 21 paratypes (16 F ad. 9.3–11.7 mm, 4 M ad. 7.9–8.9 mm, 1 F subad., NHMW 25695 , MZH HLA. 112100, MZUN, SMNH Type 8783, MFSNU) (co-occurring with eight Diamysis fluviatilis ), NW-Adriatic coast, Adige River , 9 km from its mouth into the sea, 45.1160N 012.2684E, altitude 0 m, 0.4–0.8 m depth, among flooded bank vegetation after several days of rain, roots and branches of Salix , v = 0.05 m /s, S = 0.1, 305 µS/cm, 10.6°C, pH 5.48, 8.27 mg O2/l, 8°d, 37 NTU , 14 April 2012, hand net, leg. Ariani & Wittmann.

Additional material examined (stations listed in clockwise order along Adriatic coasts). 4 F ad. 9.8–11.5 mm, 2 imm., NW-Adriatic coast, Po di Goro = mouth branch of Po River, at Mesola, 44.9251N 012.2310E, 27 km to the sea, altitude 2 m, 0.2–0.7 m depth, flooded bank vegetation, Salix , concrete, v = 0.03–0.06 m /s, S = 0.1, 442 µS/cm, 13.3°C, pH 6.43, 7.14 mg O2/l, 8°d, 81 NTU, hand net, 14 Apr. 2012, leg. Ariani & Wittmann, NHMW 25697 ; 1 F ad. 9.3 mm, 1 F imm. 8.7 mm, N-Adriatic coast, near Panzano , Canale Brancolo, 45.7804N 013.5129E, 4 km to the sea, altitude 0 m, benthic, 29 Sept. 1986, leg. F. Stoch & B. Zanolin, MFSNU; dissected parts of 1 M ad. 7.5 mm, 1 F ad. 8.5 mm with 2 postnauplioid larvae, on a total of 2 slides labelled " Paramysis helleri . Timavo. Det. Ch. Holmquist. prep. 64, 65", SMNH reg. nos . 140106, 140107, according to Stammer (1932) and Holmquist (1955: Tab. 1) this material was collected in 1928/29 by Hans Jürgen Stammer in the former right mouth branch of the Timavo , 45.7839N 013.5733E, Gulf of Trieste, NE-Adriatic; 1 F ad. 8.8 mm, 1 F imm. 6.6 mm, E-Adriatic coast, small freshwater creek at Split, roughly 43.515N 016.541E, 0–1 m depth, macrophytes, hand net, 26 Oct. 1976, leg. A. P. Ariani, NHMW 25698 ; 6 M ad. 8.3–9.4 mm, 4 F ad. 9.4–10.9 mm, 2 F subad., 1 F imm., E-Adriatic coast, lake Deran (= Deransko jezero), oligotrophic karstic lake, 43.04N 017.75E, altitude 0 m, total of about 31 km along its small effluent and following this along the Neretva River to the Adriatic Sea, sample labelled ”in clean and cold stagnant water in areas with mud bottom, specimens caught over the fine muddy sediment without any cover”, 0.5– 1 m depth, S = 0.2, 13–15°C, 9 July 2009, leg. D. Lučić & P. Tutman, NHMW 25696 .

Derivatio nominis. The species name is a Late Latin adjective with female ending, referring to the so far known exclusive occurrence of the new species in tributaries of the Adriatic Sea.

Type locality. NW-Adriatic drainage basin, in fresh-water of the lower reach of the Adige River, 45.12N 012.27E ( Fig. 12 ). This is the second-largest tributary of the Adriatic Sea.

Occurrence ( Fig. 12 ). In freshwater tributaries of the Adriatic Sea. So far known only from five running waters and one lake, in each case less than 5 m above sea level; maximum sea distance 31 km. This enumeration includes the former right mouth branch of the Timavo, now dry land. Whether Stammer (1932) found any Paramysis in other parts of the Timavo system cannot be judged currently because there is no Timavo material in the Stammer collection at the Department of Biology, University of Erlangen, Germany (Wolfgang Heimler, pers. comm.). The Swedish Museum keeps only those Timavo materials inspected by Holmquist (1955) and 60 years later by us. Inspection of Timavo springs and estuary by one of us (KJW) in Sept. 1987 yielded no Paramysis materials.

Definition. Antennal scale length is 2.5–2.6 times its maximum width; scale with smooth outer margin ending slightly before or at the terminal margin of antennular trunk or more often extending beyond this margin ( Fig. 8 B), in any case ending at a non-articulated spiniform process; setose apex is 15–25% length of scale; apex bears a small apical segment ( Fig. 8 H). Eyes with large, reniform cornea ( Fig. 8 B); maximum diameter of cornea is 42–53% antennal scale length; ventral face of eyestalks with traverse stripe of hair-like scales. Wedge- to sickle-shaped, mostly upward-bent, subrostral process extends well beyond the short, evenly rounded rostrum ( Fig. 8 B, C). This process appears subtriangular in dorsal view ( Fig. 8 B). Carapace with medium-sized, subtriangular, basally rounded, mid-dorsal, posterior emargination ( Fig. 8 C). Median segment of mandibular palp with normal (i.e. not microserrated) setae ( Fig. 9 A). Thoracic sternites 2–5 of adult males with median, apically rounded processes of different size, terminally equipped with hairs (hair-like scales); sternites 6–8 only with smooth, less distinct humps ( Fig. 9 D, E); no such processes in adult females. Thoracic endopods 3–8 with 5-segmented tarsus ( Figs 9 G, H, 10A, D, F, H); carpus as typical for the genus; propodus 3-segmented; dactylus minute, cylindrical, with small setalike nail. Endopod 3 with inner paradactylar seta ( Fig. 10 C, J) showing a heavy armature with 4–6 spinules (i.e. stiff secondary projections) along its median to subterminal portions; proximal spinules thinner, their (sub)terminal portions in part with secondary 'hairs'; outer paradactylar seta with much weaker armature ( Fig. 10 A, H). Penis with row of 4–6 short, barbed setae in subterminal position on caudolateral blade ( Fig. 9 H; same type of setae as in P. kosswigi , Fig. 5 A). Pleopods of both sexes (of males in Fig. 10 M–R) as described above for the genus; male pleopods 3 ( Fig. 10 O) and 4 ( Fig. 10 P) each with unsegmented endopod; male pleopod 4 with 6-segmented exopod ( Fig. 10 P, Q). Endopod of uropods with only 3–6 spines along inner margin between statocyst and 35–45% endopod length from tip ( Fig. 10 T). Statoliths composed of vaterite. Telson with weakly curved, allusively Sshaped lateral margins; margins with 13–15 spines, not counting the (not or) moderately larger apical spines ( Fig. 10 U, V). As an unusual state among species of Paramysis , shorter spines may alternate with longer ones on lateral margins of telson ( Fig. 10 U; this pattern distinct in 18 out of 30 specimens examined, indistinct or missing in the remaining ones; terminal spines not considered). Triangular terminal cleft is 9–12% telson length, cleft not or barely reaching the subterminal spines ( Fig. 10 U, V); cleft with almost straight margins on each symmetrical half, cleft armed with a total of 14–28 laminae of in part unequal size, even the longest laminae shorter than the subterminal or terminal spines, respectively.

Description (types only). All features within the ranges indicated above for the genus. Appendage morphology and habitus of both sexes ( Figs 7 A, B, 8A, B) very similar to those of P. a gi ge n s i s and P. hel leri . Carapace leaves 1.5–2 posterior thoracic somites dorsally exposed. Carapace with traverse row of 16–22 pores in cardial position (above the heart), arranged in two roughly symmetrical subgroups, and 7–10 pores in cervical position ( Fig. 8 C–E). Eyes dorsoventrally flattened. The cornea is reniform in dorsal view ( Fig. 8 B), ovoid in lateral view ( Fig. 8 A). Male antennula with slender appendix masculina facing obliquely downwards in the vertical plane ( Fig. 8 A) and forwards in the horizontal plane ( Fig. 8 F). This appendix is 2.0–2.3 times the length of apical segment of antennular peduncle. Sympod of antenna produced into a large spiniform process at its outer margin ( Fig. 8 H). Antennal scale ( Fig. 8 B, H) is 1.1–1.5 times the length of antennular peduncle ( Fig. 8 A, B, F, G). Large non-articulated spiniform process (thorn) at 75–90% scale length from basis. Small terminal segment of scale with five large plumose setae. Basal segment of mandibular palp without setae, but with dense field of scales ( Fig. 9 A). Remaining two segments setose. Median segment with smooth setae in both sexes; with a minor exception in males only, insofar as the basal three setae on the outer margin bear up to four subbasal to median barbs each ( Fig. 9 A). Terminal segment half as long as the median one. Exopod of maxilla roughly fan-shaped, with 12–16 mostly long, plumose ( Fig. 9 C) setae; exopod not larger than distal segment of palpus (= endopod). This palpus with terminal segment laterally widened, about 1.7–1.8 times wider than long.

First thoracic sternite produced into an anteriorly directed, distally hairy, medial lobe in both sexes ( Fig. 9 D). Unlike the sterna of males given in the definition above, the sternites 2–8 of females are medially smooth, without any humps or hairs. Basis of all thoracic exopods laterally expanded, blade-like; its distal outer corner with spinelike extension in thoracopods 1–7 ( Fig. 9 D), whereas well-rounded in thoracopod 8 ( Fig. 9 H). Flagellum of exopods 1 and 8 each with eight segments, whereas in exopods 2–7 normally with nine segments, not counting the large intersegmental joint between basis and flagellum which may be mistaken as a segment. In contrast, the flagellum of exopod 7 showed only eight segments in one out of ten females inspected in this respect. Thoracic endopods rather stout, moderately long. Total length increases from endopods 1 to endopod 3, and then decreases backward to endopod 8. Endopod 8, when stretched anteriorly, extends only up to basis of endopod 3. First thoracic epipod with groups of minute scales along its anterior margin and on intersegmental joint with its sympod ( Fig. 9 D). This sympod with additional groups of such scales and two plumose setae near insertion of epipod. First thoracic endopod with non-setose endite from coxa, and with large, setose endites from basis, ischium, and merus ( Fig. 9 D). Ischium shorter than merus in thoracic endopods 1 and 2, slightly longer in endopods 3 and 8, or distinctly longer in endopods 4–7. Paradactylar setae of endopods 3–8 weakly sickle-shaped, their armature with denticles is stronger in females ( Fig. 10 C) compared to males ( Fig. 10 J) and decreases successively in both sexes from endopods 3 to 8 (females Fig. 10 C, E, G; males Fig. 10 J–L). Penis as in Fig. 9 H. Exopod of fourth male pleopod ( Fig. 10 Q): basal segment with strong, cuticularized ridge on its rostral face; this ridge more rugged than the homologous one found on the second segment in P. kosswigi ( Fig. 5 D); the second segment in P. a dr i at i c a ( Fig. 10 Q) with less strongly oblique segmental borders compared with the homologous third segment in P. kosswigi ( Fig. 5 D). Scutellum paracaudale subtriangular with rounded tip, margins sinusoid, lower margin inconspicuously undulate ( Fig. 10 S). Endopod of uropods is 77–84% length of exopod; spine size along inner margin of endopod and space between these spines increase, with some variations, distally ( Fig. 10 T). Exopod of uropod extends 38– 44% its length beyond telson. Telson trapezoidal (apart from cleft), its maximum width near basis is 2.1–2.7 times that at apex ( Fig. 10 U), its length is 1.9–2.5 times maximum width or 1.1–1.4 times length of sixth pleonite (measured along dorsal midline).

Statoliths ( Fig. 11 A). The vaterite statoliths resemble ventrally flattened or truncated spheres, very similar to those of P. helleri ( Fig. 4 in Ariani et al. 1993) and P. l a cu s t r i s ( Figs 4 A, 6M in Wittmann et al. 1993); diameter 110–178 µm; statolith formula 2 + 3 + 1 + (5–9) + (11–16) = 22–31. Ambitus and tegmen with moruloid appearance, their surface resembling a wickerwork of lamellae. Such arrangements of lamellae often and so far exclusively found in vaterite statoliths. Ventrally the mantle does not cover the central part of the fundus, where a conical hole is typically visible (as in Fig. 11 A).

Colour. Not considering their less slender body and the larger eyes, freshly caught living specimens of the new species greatly resemble Diamysis mesohalobia mesohalobia Ariani & Wittmann, 2000 (colour photo in Ariani & Wittmann (2000): Fig. 2 F) from Fiume Piccolo (see below). General appearance yellowish brown to dark brown depending on chromatophore expansion. Rich with chromatophores all over the body and appendages. The arborescent chromatophores give brown, yellowish, and to a lesser extent also rose markings. Mainly the brown components are preserved in the ethanol-fixed specimen shown in Fig. 7 A, B.

Comparison. The new species is most similar to P. agigensis known from brackish and marine waters of the Black, Marmora, and Aegean Seas, with which it shares a short terminal lobe of the antennal scale, heavily armed inner paradactylar seta on thoracic endopod 3, and the few spines on endopod of uropod. It shares scale-like hairs on rounded lobes of anterior (2–5) male thoracic sternites with P. intermedia , P. ullskyi , P. kessleri sarsi , and P. bakuensis (for lobe morphology in Paramysis see Wittmann & Ariani (2011)). In contrast, there are no hairs on the rounded lobes of P. h e l l er i, P. festae , and P. nouveli , or on the less well-rounded lobes of P. k ro y er i. There are also smooth, but smaller, less distinct lobes in P. arenosa ( G. O. Sars, 1877) . The respective lobes are not rounded but subtriangular to sickle-shaped at least in large males of P. a gi ge n s i s, P. pontica , and P. bacescoi .

Additional differences of P. a dr i at i c a from its most similar (Ponto-)Mediterranean congenerics: from P. he l l e r i by shallower telson cleft (15–24% telson length in the latter), stouter antennal scale (2.8–3.9 times as long as wide in P. he l l e r i), strong, less numerous secondary spinules (about 20 thin distal setules in P. he l l e r i) on the paradactylar setae in endopods 3–8, reminiscent of those of P. agigensis , and by fewer spines on the endopod of uropods (7–13 in P. helleri ), also like in P. ag i g e n s i s. The new species differs from P. f e s t a e by smaller eyes, a longer antennal scale, and a greater number of laminae in the telson cleft. It differs from P. agigensis by a shallower telson cleft (15–19% telson length in P. agigensis ) not or barely reaching up to the penultimate lateral spines (almost reaching the antepenultimate spines in P. agigensis ), by slightly stouter antennal scale (2.8–3.0 times as long as wide in P. agigensis ), but slightly longer apical part of the antennal scale (16–18% scale length in P. a gi ge n s i s), and by the presence of 4–6 short, barbed setae on caudolateral blade of penis (1–3 long, smooth setae in P. agigensis ).

Pleopods of two adult males each from shallow brackish waters at sandy beaches were dissected for P. he l l e r i from the North Adriatic Sea ( Spiaggia die Ponente , Caorle, Italy, 45.5814N 012.8513E, S = 17, leg. KJW) and P. agigensis from the Sea of Marmora (Büyükada Islands, Turkey, 40.8594N 029.1126E, again S = 17, leg. KJW). The fourth pleopod of both species differed from that in P. adriatica by two-segmented (versus unsegmented) endopod and 7-segmented (versus 6-segmented) exopod, the latter showing a weaker, less strongly ridge-like differentiation at its upper surface near the end of its second segment (corresponding to the basal segment in P. adriatica ).

Figures

FIGURE 2. Distribution of Hemimysis anomala G. O. Sars, 1907, and Mesopodopsis slabberi (Van Beneden, 1861), in tributaries and coastal waters of the Mediterranean and Black seas. Data original and from 135 literature sources.

FIGURE 4. Paramysis (Serrapalpisis) kosswigi Băcescu, 1948, from Lake Işikli (A – D, F – K) and its springs (E, type locality) in Anatolia. A, anterior body region of adult male with body length 8.7 mm, dorsal view (pores on carapace and scales on eyestalks not to scale); B, antenna of male 9.1 mm, ventral; C, left mandibular palp of male 9.1 mm, rostral; D, detail of (C) showing setae from the outer margin of the median segment; E, setae as in (D), female 10.5 mm; F, thoracic sternites 1 – 8 of male 8.9 mm, ventral; G, the same for female 10.1 mm; H, left ' tarsus' (carpopropodus plus dactylus) of thoracic endopod 3 in female 10.1 mm, rostral; J, anterior paradactylar seta in female 9.5 mm; K, the same for male 9.1 mm.

FIGURE 5. Paramysis (Serrapalpisis) kosswigi Băcescu, 1948, from Lake Işikli in Anatolia. A, left penis of male with body length 8.2 mm, outer lateral; B, third pleopod in male 8.7 mm, rostral face; C, the same for fourth pleopod; D, exopod of fourth pleopod in lateral view, setae omitted, male 9.6 mm; E, fifth pleopod in male 8.7 mm, rostral; F, posterior margin of sixth pleonite in female 10.1 mm, lateral; G, the same for male 9.1 mm; H, uropods of male 8.7 mm, ventral; J, telson of same male, dorsal; K, detail of (J), showing right terminal spine and its neighbouring laminae.

FIGURE 7. Paramysis (Longidentia) adriatica sp. nov. (A, B) and Troglomysis vjetrenicensis Stammer, 1933 (C). A, B, ethanol fixed adult female with body length 11 mm, from the Adige River, paratype, in dorsal (A) and in lateral (B) view (MZH reg. no. HLA. 112100); C, ethanol fixed adult male 12.5 mm, from the type locality within the cave Donja Vjetrenica, lateral. A, B, photo M. Daneliya; C, photo A. P. Ariani.

FIGURE 8. Paramysis (Longidentia) adriatica sp. nov. from the Adige River, holotype, male with body length 9.1 mm (A), paratypes female 9.5 mm (B), male 7.9 mm (C – F, H, K), and female 10.9 mm (G, J). A, male habitus, lateral; B, anterior body region of female, dorsal; C, carapace expanded on slide, dorsal, details show cervical (D) and cardial (E) pore groups; F, antennula of male, dorsal; G, antennula of female, dorsal; H, antenna, ventral; J, labrum, ventral; K, maxillula, caudal.

FIGURE 9. Paramysis (Longidentia) adriatica sp. nov. from the Adige River, paratypes, male with body length 7.9 mm (A – F, H), and female with 10.9 mm (G). A, mandibles, rostral; B, labium, caudal; C, maxilla, rostral; D, male thoracic sternites 1 – 8 (ventral) with left first thoracopod (caudal); E, lateral view on male sternal processes or humps in the sagittal plane; F, second thoracic endopod, caudal; G, sixth thoracic endopod with rudimentary oostegite, rostral; H, eighth thoracopod (caudal) with penis (postero-lateral blade of penis is accidentally shifted antero-laterally).

FIGURE 10. Paramysis (Longidentia) adriatica sp. nov. from the Adige River, paratypes, female with body length 10.9 mm (A – G, V), and males with 7.9 mm (H – P, R – U) or 9.1 mm (Q), respectively. A, female tarsus 3, i. e. tarsus of third thoracic endopod, rostral, details show a modified seta (B) of the propodus, and the rostral paradactylar seta (C); D, female tarsus 4, rostral, detail (E) as in (C); F, female tarsus 8, rostral, detail (G) as in (C, E); H, male tarsus 3, rostral, detail shows the rostral paradactylar seta (J); K, L, male rostral paradactylar setae of thoracic endopods 4 (K) and 8 (L); M – P, series of male pleopods 1 – 4, caudal (M, N) or rostral (O, P) view; Q, exopod of male pleopod 4 in lateral view, setae omitted; R, male pleopod 5, caudal; S, posterior margin of sixth pleonite, lateral; T, uropods, ventral; U, telson, dorsal; V, terminal portion of telson, dorsal.

FIGURE 11. Vaterite (A) and fluorite (B) statoliths in Mediterranean freshwater mysids. A, Paramysis adriatica sp. nov. from small creek at Split, oblique ventro-lateral view on right statolith of adult female with body length 8.8 mm; B, Troglomysis vjetrenicensis from the cave Donja Vjetrenica (type locality), ventral view on right statolith of adult male 12.5 mm (statolith somewhat deteriorated upon treatments related to SEM study and X-ray diffraction analysis by Ariani et al. 1993). A, B, SEMmicrographs by A. P. Ariani.

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).