Eocyzicus occidentalis, Tippelt & Schwentner, 2018

Tippelt, Lisa & Schwentner, Martin, 2018, Taxonomic assessment of Australian Eocyzicus species (Crustacea: Branchiopoda: Spinicaudata), Zootaxa 4410 (3), pp. 401-452 : 436-437

Eocyzicus occidentalis sp. nov.

( Fig. 19a and b )

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

Etymology. The species name is derived from Latin "occidens" meaning western as the species was recorded in Western Australia.

Type locality. Western Australia, Muggon claypan, via Carnarvon, 26°46´54´´S, 115°40´53´´E.

Type material. Holotype. Male (Western Australian Museum Registration number 55045, GenBank KC583812 ), collected by B. V. Timms, 08-VII-2011.

Further material examined. No material from other localities available

Description. Holotype male ( Fig. 19a and b ). Carapace. 4.2 mm high, 6.6 mm long, height/length ratio 0.64; height without "crowded" growth lines 4.1 mm, length without "crowded" lines 6.1 mm; shape oval; dorsoposterior corner clearly present; 33 growth lines, of these 29 "non-crowded" and four "crowded"; umbo small, hemispheric, growth lines present ( Fig.19a ).

Head. Condyle rounded, section between condyle and external eye contour straight; eye bulge absent, compound eye oval; straight angle between head and rostrum; anterior margin of rostrum straight, transition between anterior and ventral margin rounded ( Fig. 19b ). Antennule with 21 lobules, widely arranged; reaches to 13th antennary segment. Antenna with 14 antennary segments, middle antennary segment anteriorly with four spines.

Thorax. 20 thorax segments, of these 19 "complete" and one "incomplete"; dorsal spines beginning at 8th thorax segment, twelve thorax segments with dorsal spines; one dorsal spine at each thorax segment, first dorsal spine smaller than following one; last dorsal spine smaller than preceding one, last "complete" thorax segment with dorsal spine.

Telson. 16 telsonic spines without enlarged, telsonic spines end at base of apex; telson symmetric; telsonic filaments situated between second and third telsonic spine. Furca with eight setae. Assessment of presence of small spine before row of spinules, of the length of setae and the length of spinules was not possible due to damaged furcae.

Differential diagnosis. The putative sister species of Eocyzicus occidentalis sp. nov. could not be unambiguously identified in the phylogenetic analyses by Schwentner et al. (2014), but it appeared closely related to E. richteri sp. nov. and E. breviantennus sp. nov. Morphologically it resembles Eocyzicus timmsi sp. nov. and E. richteri sp. nov. ( Fig. 2a ), but can be distinguished by the number of all growth lines, number of lobules on the antennules (only E. timmsi sp. nov.), number of segments at the antenna and number of telsonic spines (latter two characters only for E. richteri sp. nov.; Table 1). Hence, this species can be considered a separate species based on the PSC (Wheeler & Platnick, 2000) and the ESC (Wiley & Mayden, 2000). However, due to its allopatric distribution in relation to all other Australian Eocyzicus species a delimitation following the BSC (Mayr, 1942) remains ambiguous.

Distribution and ecology. E. occidentalis sp. nov. was recorded from a single turbid claypan and does not occur sympatrically with any other studied Eocyzicus 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.

FIGURE 19. Eocyzicus occidentalis sp. nov. and E. careyensis sp. nov. a–b, E. occidentalis sp. nov. (AM P.89447). a, carapace of male holotype. b, head of male holotype (telson is not shown due to severe damage). c–e, E. careyensis sp. nov. (AM P.89448).c, carapace of femaleholotype.d, head of female holotype.e,telson of female holotype.ce = compound eye,co = condylus, ds = dorsal spine,fu = furca, gl= growth lines, is = „incomplete" thoraxsegments, md = mandible,ro = rostrum, sp = spinules, tf = telsonic filaments, ts = telsonic spines, um = umbo.