Eulimnadia contraria, Brian V Timms, 2016

Brian V Timms, 2016, A partial revision of the Australian Eulimnadia Packard, 1874 (Branchiopoda: Spinicaudata: Limnadiidae), Zootaxa 4066 (4), pp. 351-389 : 367-369

Eulimnadia contraria sp. nov.

( Figs. 9 A,10)

Etymology. The specific epithet is based on the Latin ‘contrarius’ meaning opposites and refers to the numerous telsonic spines yet few short cercopod setae and to the numerous short spines on the antennomeres as against the sparse setae on many (both numerals are departures from the ‘average’ morphology in Eulimnadia ).

Type locality. Queensland, Aramac district, vicinity of Lake Dunn, excavation on south side of lake, 22o 36’ 12”S, 145o 40’ 26”E, 15 February 2010, MS and BVT.

Type material. Holotype. Hermaphrodite in Australian Museum, Sydney, length 9.8 mm, height 6.4 mm, AMP 91973.

Paratype. Hermaphrodite in Australian Museum, Sydney, length 9.6 mm, height 6.2 mm. AMP 91974..

Diagnosis. Egg with about 15 large deep polygons with long narrow protrusions laterally at ridge junctions. 18 trunk segments. Cercopod with a few short setae spaced along basal 80%. About 24 telsonic spines, all except first and last about same size. Female carapace much vaulted dorsally.

Description. Egg ( Fig 9 A) largely spherical but with many soft narrow protrusions at the ridge junctions of the approximately 15 polygons. These polygons deep with smooth inner slopes to a central short groove. Mean diameter 188 Μm (range 178–197 ìm, n = 5).

Hermaphrodite. Head ( Fig 10 C) with ocular tubercle prominent, the compound eye occupying most (ca 80%) of it. Rostrum hardly protruding, evenly rounded, ocellus small, placed above centre. Frons-rostrum angle 160o. Dorsal organ posterior to eye by about its height, pedunculate and of similar height as ocular tubercle.

First antenna a little longer than peduncle of second antenna and with about 8 lobes.

Second antenna with a spinose peduncle and each flagella with 8 antennomeres, dorsally with 3–8 short spines and ventrally with 0–5 longer setae. Setae most numerous on distal 2 antennomeres and sparse elsewhere, spines most numerous on intermediate antennomeres.

Carapace ( Fig 10 A) opaque and discoloured dull yellow and much vaulted dorsally and with numerous (ca. 8) growth lines.

Thoracopods. Eighteen pairs of typical structure for Eulimnadia . Trunk dorsum with 3–9 setae terminally, these setae few, short and stout on distal few segments, numerous and longer on segments 8–15 and hardly any setae on anterior trunk segments 1–7.

Telson ( Fig 10 B) with spine at ventroposterior angle, dorsally with about 24 naked spines, each about the same size and spacing except the first about 1.5x height of others, and the last about 3x height of others. Caudal filaments originating from a mound a little higher than telsonic floor and at the fifth spine. Dorsal floor declines from mound almost evenly to cercopod base. Cercopod a little longer than telson, the basal 80% with about 7 widely spaced, short setae and demarked from the last 20% by a short spine and thinning to an acute apex. Many tiny denticles dorsolaterally on apical 20%.

Comments. The markedly vaulted carapace and large number of growth lines could be associated with the advanced age of the holotypic specimen. The numerous dorsal spines and few setae on most antennomeres could be an aberration and not definitive of this species. More distinctive are the few cercopod setae, most of which are only 0.5 x cercopod diameter. This species is Eulimnadia sp. E of Schwentner et al. (2015). Despite the lack of males and the availability of only two specimens it was described as it is one of the few species able to be matched with molecular species delineated by Schwentner et al. 2015.

Distribution. Eulimnadia contraria is known only from its type locality in central Queensland.

Figures

FIGURE 9. Eulimnadia eggs. A, E. contraria sp. nov. (Lake Dunn, Qld); B, E. gnammaphila Kooyoora, Vic); C, E. gnammaphila (Peela, SA); D, E. gnammaphila (Yanneymooning, WA); E. hansoni (Bloodwood, NSW); F, E. pinocchionis (Karratha, WA), G, E. taroomaensis (Taroom, Qld), H, E. uluruensis (Uluru, NT); enlargement of portion of egg of E. uluruensis. Scale bars 1 mm, except I for which the bar = 0.01 mm.

FIGURE 10. Eulimnadia contraria sp. nov. Lake Dunn, Qld .. A, female carapace; B, female telson, C, female head and antennae. Scale bars 1 mm.