Eulimnadia canalis, 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 : 363-365

Eulimnadia canalis sp. nov.

( Figs 3 G, 7)

Etymology. The specific name ‘canalis’ is Latin and means canal or groove and refers to the egg of this species which has many long grooves in the tertiary layer.

Type locality. New South Wales, 120 km NE of Bourke, Bloodwood Station, a clay pan locally known as ‘Dead Ram,’ 5 km W of homestead, 29o 31’ 46.7”S, 144o 52’ 2.5”E, 21 February 2011, BVT.

Type material. Holotype. Hermaphrodite deposited in Australian Museum, 6.8 mm long, 4.6 mm high, registration number AM P97832.

Paratypes. Hermaphrodites deposited in Australian Museum, 7.3 mm long by 5.0 mm high and 6.6 mm by 3.9 mm, registration number AM P97833.

Other material. New South Wales: Ten hermaphrodites, 120 km NE of Bourke, Bloodwood Station, Homestead Blackbox Swamp, 29o 31’ 29”S, 144o 53’ 28”E, 21 February 2011, BVT and MS, AM P97834.

Diagnosis. Egg with about 35 narrow, deep grooves, length of each about 40% the egg diameter. 18 trunk segments. Telson with about 15 dorsal spines and cercopod with about 16 long (about 2.5x cercopod diameter) setae.

Description. Egg. ( Fig 3 G) Spherical, 148 Μm (range 144–153 ìm, n=5) in diameter, with about 35 narrow, deep grooves each about 40% of the diameter and most curved longitudinally. Ridges between grooves broad, rounded. Tertiary layer spongiform and and surface microporous.

Hermaphrodite. Head ( Fig 7 B) with ocular tubercle prominent, the compound eye occupying most (ca. 70%) of it. Rostrum broadly rounded protruding a little less than ocular tubercle with ocellus almost as large as the eye basodorsally. Frons-rostrum angle about 110o. Dorsal organ posterior to eye by a little more than is height; height about two-thirds ocular tubercle height.

First antennae a little longer than peduncle of second antennae and with about five lobes each with many small sensory setae.

Second antennae with 9 antennomeres dorsally and 10 ventrally, each antennomere with 1–7 dorsal spines and 3–6 ventral setae, most with 4–6 spines and 4–5 setae. Basal and two distal antennomeres with most aberrant numbers.

Carapace ( Fig 7 A) pellucid, elongated oval with dorsal edge vaulted, maximum height at about 2/5ths length. About 4 growth lines. Adductor muscle about 40o to long axis of carapace, but difficult to see.

Thoracopods Eighteen a pairs of typical Eulimnadia structure.

Trunk dorsum with 1–9 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 with 15 pairs of dorsal spines, anterior spines, particularly 4–7 more spaced than posterior spines; most spines with denticles. Caudal filaments on a mound between spines 4 and 5. Telsonic floor posterior to mound with a marked declivity, then sloping away gently to cercopod base. Cercopod a little longer than telson with basal 80% hardly narrowing and with about 16 setae of moderate length, each about twice its diameter and feathered. Distal 20% of cercopod narrowing to an acute apex and with many denticles dorsolaterally. The two zones of the cercopod demarked with a small spine. Prominent spiniform projection beneath the cercopod at the ventroposterior corner of the telson.

Variability. With only three specimens available and all from one site, the full range of variation is unrecorded. Flagella of second antennae had 8–10 antennomeres, average near 9. In some specimens there were few dorsal spines and ventral setae. Telsonic spines ranged from 13 to 16 with those at about 3–7 always spaced a little more. Cercopod setae varied in number from 14–18, with sometimes the first one or two shorter than the rest.

Comments. This species besides occurring at two sits on Bloodwood Station in the NSW part of the Paroo, has a distinctive egg which was seen in material from a swamp south of Thargomindah in the adjacent Bulloo catchment but not assignable for sure to respective specimens. Otherwise it is most similar to E. dahli and E. taroomaensis sp. nov. in that it has many (>14) moderate to long cercopod setae. However E. dahli has>18 setae and 20 trunk segments whereas E. canalis sp. nov. has <16 setae and 18 trunk segments, and in E. taroomaensis sp. nov. the setae are shorter distally while in E. canalis sp. nov. all setae are similar in length.

Distribution. Paroo and Bulloo catchments, northwestern NSW and southwestern Queensland.

Figures

FIGURE 3. Eulimnadia eggs. A, E. dahli Sars, (Phillips Gorge, WA); B, E. dahli Sars, (Charlotte Waters, NT); C, E. australiensis sp. nov. (Moonbi. NSW); D, E. australicemsis sp. nov. (Nudgee, Qld); E, near E. australiensis sp. nov?, (Bloodwood, NSW); F. E. beverleyae sp. nov. (Bloodwood, NSW), G, E. canalis, sp. nov. (Bloodwood, NSW). H, E. centenaria (Kings Tableland, NT) sp. nov., I, enlargement of part of egg of E. centenaria sp. nov. Scale bars 0.5 mm, except for I for which the bar = 0.01 mm.

FIGURE 7. Eulimnadia canalis sp. nov. Bloodwood, NSW. A, female carapace; B, female head and antennae; C, female telson. Scale bars 1 mm.