Eocyzicus armatus, Tippelt & Schwentner, 2018

Tippelt, Lisa & Schwentner, Martin, 2018, Taxonomic assessment of Australian Eocyzicus species (Crustacea: Branchiopoda: Spinicaudata), Zootaxa 4410 (3), pp. 401-452 : 433-436

Eocyzicus armatus sp. nov.

( Figs. 17 and 18 )

Eocyzicus lineage Z Schwentner et al., 2014, 2015b

Etymology. The species name " armatus ", which means armed, corresponds to the large number of telsonic spines and differentiates this species from the majority of all other Australian Eocyzicus species.

Type locality. New South Wales, Murray-Darling Basin , Paroo River catchment, Bloodwood Station, Roszkos Paleolake, 29°27´42.9´´S, 144°48´12.5´´E.

Type material. Holotype. Male (AM P.89602, GenBank KC583965 ).

Allotype. Female (AM P.89599, GenBank KC583962 ).

Paratypes. 3 males (AM P.89589, GenBank KC583952 ; AM P.89598, GenBank KC583961 ; AM P.91860, no COI sequence available), 4 females (AM P.91859, no COI sequence available; AM P.89600, GenBank KC583963 ; AM P.91861, no COI sequence available; AM P.89601, GenBank KC583964 ) collected by M. Schwentner and B. V. Timms, 19-II-2010.

Further material examined. New South Wales: 1 male (AM P.89597) Freshwater Lake, Bloodwood Station , 29°29´14.7´´S, 144°49´59.0´´E, 19-II-2010 ; Northern Territory: 1 male (AM P.89611) , 1 female (AM P.89610) Lake 20 km of West Erldunda , 25°14´36.5´´S, 132°59´40.3´´E, 10-III-2011 ; 1 male (AM P.89605) Island hyposaline lake 60 km of North Kulgera , 25°19´23.2´´S, 133°12´41.7´´E, 10-III-2011 ; Western Australia: 3 males (AM P.80900, AM P.89590, AM P.89591) , 3 females (AM P.89592, AM P.89593, AM P.89594) Deep samphire swamp near Onslow , 21°43´12.3´´S, 115°05´56.5´´E, 12-III-2009 ; 1 female (AM P.89603) Samphire swamp a few km south of Onslow , 21°43´S, 115°05´E, 14.03.2009 .

Description. Holotype male ( Fig. 17 a, c and d ). Carapace. 4.5 mm high, 7.2 mm long, height/length ratio 0.63; height without "crowded" growth lines 4.1 mm; length without "crowded" growth lines 6.6 mm; shape oval; dorso-posterior corner clearly present; 16 growth lines, of these 15 "non-crowded" and one "crowded"; umbo small, hemispheric, growth lines present ( Fig. 17a ).

Head. Condyle rounded, section between condyle and external eye contour concave; eye bulge large, compound eye round; acute angle between head and rostrum; anterior margin of rostrum convex, transition between anterior and ventral margin angular ( Fig. 17c ). Antennule with 17 lobules, widely arranged; reaches to 8th antennary segment. Antenna with twelve antennary segments, middle antennary segment anteriorly with four spines.

Thorax. 23 thorax segments, of these 21 "complete" and two "incomplete" ( Fig. 17d ); dorsal spines beginning at 8th thorax segment, 14 thorax segments with dorsal spines; one dorsal spine at each thorax segment, first dorsal spine same size as following one; last dorsal spine smaller than preceding one; last "complete" thorax segment with dorsal spine ( Fig. 17d ).

Telson. 13 telsonic spines, of these three enlarged, telsonic spines end after base of apex; telson symmetric; telsonic filaments situated between second and third telsonic spine. Furca with twelve setae, longer than proximal part of furca; small spine before row of spinules present, spinules short ( Fig. 17d ).

Allotype female ( Fig. 17 b, e and f ). Carapace. 4.3 mm high, 6.8 mm long; height without "crowded" growth lines 3.8 mm, length without "crowded" growth lines 5.9 mm; 15 growth lines, of these 13 "non-crowded" and two "crowded" ( Fig. 17b ).

Head. Eye bulge small; obtuse angle between head and rostrum; anterior margin of rostrum straight ( Fig. 17e ). Antennule reaches to third antennary segment. Antenna with 13 antennary segments, middle antennary segment anteriorly with five spines.

Thorax. 21 thorax segments; of these 20 "complete" and one "incomplete" ( Fig. 17f ); dorsal spines beginning at 7th thorax segment, 13 thorax segments with dorsal spines; first dorsal spine smaller than following one, last dorsal spine same size as preceding one, last "complete" thorax segment without dorsal spine ( Fig. 17f ).

Telson. 19 telsonic spines, of these six enlarged; telsonic spines end at base of apex; telsonic filaments situated between fourth and fifth telsonic spine ( Fig. 17f ).

Ovigerous flagella situated at 9th and 10th thorax segment.

Variability. Males. Carapace. 4.3–7.1 mm, 4.5–8.4 mm, height/length ratio 0.61–0.72, height without "crowded" growth lines 3.4–4.6 mm, length without "crowded" growth lines 5.7–7.2 mm; dorso-posterior corner clearly present or nearly absent; 15–35 growth lines, of these 12–27 "non-crowded" and 1–13 "crowded"; umbo cone-shaped, or hemispheric, growth lines present or absent.

Head. Section between condyle and external eye contour concave or straight; eye bulge absent or present, if present small, compound eye oval or round; acute to right angle between head and rostrum; anterior margin of rostrum straight or convex ( Fig. 18a ). Antennule with 13–20 lobules ( Fig. 18b ); reaches to 7th–10th antennary segment. Antenna with 12–14 antennary segments ( Fig. 18c ), middle antennary segment anteriorly with four to six spines ( Fig. 18d ).

Thorax. 20–23 thorax segments, of these 19–21 "complete" and one or two "incomplete" ( Fig. 18g ); dorsal spines beginning at 5th–11th thorax segment, 10–17 thorax segments with dorsal spines; first dorsal spine smaller than or same size as following one, last dorsal spine smaller than or same size as preceding one, last "complete" thorax segment with or without dorsal spine ( Fig. 18g ).

Telson. 11–23 telsonic spines, of these four to six enlarged; telsonic spines end at or after base of apex; telsonic filaments situated between 2nd and 7th telsonic spine. Furca with 10–19 setae, spinules short or long ( Fig. 18g ).

Variability. Females. Carapace. 4.3–5.1 mm high, 6.7–7.7 mm long, height/length ratio 0.61–0.66; height without "crowded" growth lines 3.3–4.8 mm; length without "crowded" growth lines 5.2–7.1 mm; dorso-posterior corner clearly present or nearly absent, 14–38 growth lines, of these 13–24 "non-crowded" and 2–15 "crowded"; umbo small or large, cone-shaped or hemispheric, growth lines present or absent.

Head. Section between condyle and external eye contour concave or straight; eye bulge absent or present, if present small or large, compound eye oval or round; acute or obtuse angle between head and rostrum; anterior margin of rostrum concave, straight or convex, transition between anterior and ventral margin rounded or angular. Antennule with 14–17 lobules, closely or widely arranged; reaches to third to sixth antennary segment. Antenna with 10–13 antennary segments, middle antennary segment anteriorly with four or five spines.

Thorax. 21–23 thorax segments, of these 19–22 "complete" and one or two "incomplete"; dorsal spines beginning at 6th–10th thorax segment, 11–15 thorax segments with dorsal spines; last dorsal spine smaller than or same size as preceding one; last "complete" thorax segment with or without dorsal spine.

Telson. 18–28 telsonic spines, of these up to six enlarged, telsonic spines end at or after base of apex; telsonic filaments situated between 3rd and 7th telsonic spine. Furca with 9–18 setae, as long as or longer than proximal part of furca; small spine before row of spinules present or absent.

Differential diagnosis. The species that morphologically is most similar to Eocyzicus armatus sp. nov. is E. parooensis . It is possible to distinguish both species by the number of all growth lines on the carapace, of thorax segments and of telsonic spines ( Table 1 and 2). The sister species could not be identified by genetic analyses. Nevertheless, its clear differentiation from all other Eocyzicus species (Schwentner et al., 2014) supports its delimitated as a species following the PSC sensu Wheeler & Platnick (2000), ESC (Wiley & Mayden, 2000) and BSC (Mayr, 1942). With regard to the species it occurs sympatrically with, it can also be delimited following the BSC (Mayr, 1942).

Distribution and ecology. This species is distributed in clear, fresh and hyposaline water bodies and occurs sympatrically with E. richteri sp. nov., E. phytophilus sp. nov., E. argillaquus , E. parooensis and E. ubiquus sp. nov. and is rarely syntopically distributed with the latter species.

Figures

FIGURE 17. Eocyzicus armatus sp. nov. a, carapace of male holotype (AM P.89602). b, carapace of female allotype (AM P.89599). c, head of male holotype. d, telson of male holotype. e, head of female allotype. f, telson of female allotype.; ce = compound eye, co = condylus, ds = dorsal spine, fu = furca, gl = growth lines, is = „incomplete" thorax segments, md = mandible, ro = rostrum, sp = spinules, tf = telsonicfilaments, ts = telsonic spines, um = umbo.

FIGURE 18. Eocyzicus armatus sp. nov. male paratype (AM P.91860). a, rostrum (left antenna removed). b, antennule. c, left antenna.d, fourth and fifthsegment of the left antenna.e, first right clasper, arrow indicates the scales at the tip of the movable finger.f, detail of the tipof the movablefinger offirst rightclasper.g,telson, arrowsindicate "incomplete" thoraxsegments.A1 = antennules, ds = dorsal spine, fu = furca, lp = large palpus, mf = movable finger, ro = rostrum, sc = scales, sp = spinules, tf = telsonic filaments, ts = telsonic spines.