Eocyzicus argillaquus Timms & Richter, 2009

Tippelt, Lisa & Schwentner, Martin, 2018, Taxonomic assessment of Australian Eocyzicus species (Crustacea: Branchiopoda: Spinicaudata), Zootaxa 4410 (3), pp. 401-452 : 438-440

Eocyzicus argillaquus Timms & Richter, 2009

Eocyzicus sp. b Timms & Richter 2002

Eocyzicus argillaquus, Timms & Richter 2009 ; Schwentner et al., 2009; Schwentner et al., 2014, 2015b

Material examined. New South Wales: 1 male (AM P.89346) , 1 female (AM P.89352) Lower Lake Eliza, Muella Station , 29°25´28.9´´S, 145°03´41.8´´E, 20-II-2010 ; Queensland: 1 male (AM P.89392) Gidgee claypan 9 km on Tenham, Station, 25°41´02.4´´S, 143°00´59.4´´E, 28-II-2011 ; 1 female (AM P.89396) Horse paddock claypan on Springfield Station , 25°49´29.6´´S, 143°04´07.9´´E 01-III-2011 ; 1 female (AM P.89388) Yapunyah pool, 27°49´09.6´´S, 144°09´26.5´´E, 28-II-2011 ; 1 female (AM P.89380) Toebiter claypan, 28°02´30.8´´S, 144°17´50.7´´E, 27-II-2011 ; 1 male (AM P.89385) Claypan 45 km east of Thargomindah , 28°05´15.0´´S, 144°15´47.0´´E, 27-II-2011 ; 1 male (AM P.89368), 1 female (AM P.89366) Big Darko claypan, Currawinya National Park 28°52´19.1´´S, 144°17´34.5´´E, 25-II-2011 ; 1 female (AM P.89355) Claypan north of windmill, Currawinya National Park , 28°48´28.8´´S, 144°18´09.1´´E, 24-II-2011 ; 1 male (AM P.89360), 1 female (AM P.89361) Well-vegetated claypan, Currawinya National Park , 28°47´19.4´´S, 144°17´43.3´´E, 24-II-2011 ; 1 female (AM P.89365) Vegetated claypan near Bilby enclosure, 28°52´16.2´´S, 144°24´37.3´´E, 24-II-2011 ; 1 male (AM P.89375) Claypan halfway up northern fence of Bilby enclosure, Currawinya National Park , 28°52´12.8´´S, 144°21´52.1´´E, 25-II-2011 ; South Australia: 1 male (AM P.89407) , 1 female (AM P.89406) Vegetated stony dugout 34 km north of Marla , 27°05´26.8´´S, 133°28´16.2´´E, 10-III-2011 ; 1 female (AM P.89413) Old small dugout 105 km east of Marla , 27°10´00.2´´S, 134°33´07.2´´E, 11-III-2011 ; 1 male (AM P.89416) Daisy claypan 106 km east of Marla , 27°10´02.2´´S, 134°33´30.7´´E, 11-III-2011 ; 1 male (AM P.89426) Dam 60 km north of Oodnadatta , 27°03´13.4´´S, 135°15´04.4´´E, 11-III-2011 ; 2 males (AM P.89 428, AM P.89429) Deepened claypan 19 km south of William Creek , 29°04´55.0´´S, 136°31´59.5´´E, 12-III-2011 .

Variability. Males. Carapace. 3.3–5.0 mm high, 5.2–7.8 mm long, height/length ratio 0.61–0.67; height without "crowded" growth lines 2.9–4.7 mm, length without "crowded" growth lines 4.4–7.3 mm; dorso-posterior corner clearly present or nearly absent; 20–25 growth lines, of theses 13–25 "non-crowded" and up to ten "crowded"; umbo cone-shaped or hemispheric; growth lines present or absent.

Head. Section between condyle and external eye contour concave, straight or convex; eye bulge absent or present, if present small, or large; compound eye oval or round; obtuse to straight angle between head and rostrum; anterior margin of rostrum straight or convex; transition between anterior and ventral margin rounded or angular. Antennule with 15–25 lobules, closely or widely arranged; reaches to 7th –11th antennary segment. Antenna with 11–13 antennary segments, middle antennary segment anteriorly with four to six spines.

Thorax. 19–22 thorax segments, of these 18–20 "complete" and one or two "incomplete"; dorsal spines beginning at 5th –9th thorax segment, 11–14 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.

Telson. 13–17 telsonic spines, of these one to five enlarged; telsonic spines end at or after base of apex; telson symmetric; telsonic filaments situated between the second and fifth telsonic spine. Furca with five to twelve setae, shorter or longer than proximal part of furca; small spine before row of spinules present or absent.

Variability. Females. Carapace. 2.6–6.1 mm high, 4.3–9.1 mm long, height/length ratio 0.60–0.71; height without "crowded" growth lines 2.6–5.7 mm, length without "crowded" growth lines 4.3–8.6 mm; dorso-posterior corner clearly present or nearly absent; 18–29 growth lines, of these 18–25 "non-crowded" and up to eleven "crowded"; umbo small or large, growth lines present or absent.

Head. Section between condyle and external eye contour straight or convex; compound eye oval or round; obtuse to straight angle between head and rostrum, anterior margin of rostrum straight or convex, transition between anterior and ventral margin rounded or angular. Antennule with 12–19 lobules, closely or widely arranged; reaches to fifth or sixth antennary segment. Antenna with 11–14 antennary segments, middle antennary segment anteriorly with four to seven spines.

Thorax. 20–22 thorax segments, of these 19–20 "complete" and one or two "incomplete"; dorsal spines beginning at 5th –10th thorax segment, 11–15 thorax segments with dorsal spines; first dorsal spine smaller than or same size as following one, last dorsal spine smaller than, same size as or larger than preceding one, last "complete" thorax segment with or without dorsal spine.

Telson. 14–19 telsonic spines, of these up to three enlarged, telsonic spines end at or after base of apex; telson symmetric; telsonic filaments situated between the second and fifth telsonic spine. Furca with five to nine setae, shorter than, as long as or longer than proximal part of furca; spinules short or long.

Differential diagnosis. Eocyzicus argillaquus is morphologically similar to E. ubiquus sp. nov. and E. timmsi sp. nov. It is possible to differentiate E. argillaquus and E. ubiquus sp. nov. by the number of all growth lines and number of telsonic spines ( Tables 1 and 2). Eocyzicus timmsi sp. nov. and E. argillaquus could not be separated in the PCA and CVA ( Fig. 2 ), because of the large intraspecific variability exhibited by both species. However, they differ in the range and mean of several characters ( Table 1 and 2), which may allow morphological species identification if multiple individuals per population are examined, and are genetically well differentiated (Schwentner et al., 2014). They are certainly not sister species but rather distantly related.

The morphological intraspecific variability determined by Timms & Richter (2009) was in general much larger than the one described herein ( Table 4). Most likely Timms & Richter (2009) inadvertently included individuals of other Eocyzicus species that occur in the studied area.

Distribution and ecology. This species occurs exclusively in very turbid, freshwater pools (mainly claypans) and is sympatrically distributed with Eocyzicus ubiquus sp. nov., E. armatus sp. nov., E. breviantennus sp. nov., E. parvus sp. nov., E. richteri sp. nov. and E. phytophilus sp. nov. It occurs rarely syntopically with the latter two species.

Figures

FIGURE 2. Principal Components Analysis (PCA) and Cannonical Variates Analysis (CVA). In the CVA specimens are assigned to species prior to analysis, whereas no such assignment is done in the PCA. a, PCA of males. b, CVA of males. c, PCA of females. d, CVA of females. Each square corresponds to one individual.Bold arrows indicate the single individuals of E.occidentalissp.nov and E.careyensis sp. nov., respectively.Axeswith most importantcharacters are displayed inlight grey.