Eulimnadia uluruensis, 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 : 381-383

E. uluruensis sp. nov.

(Figs.,9H,I, 17)

Etymology. The species is named after Uluru, the large monolith in the centre of Australia. It occurs in gnammas on top of this rock and also in small ponds on the adjacent Kata Tjuta rocks.

Type locality. Northern Territory, Kata Tjuta, Valley of the Winds, small rocky pond, 25o 17’ 22.3”S, 130o 44’ 18.8”E.

Type material. Holotype. Male deposited in Australian Museum, Sydney, length 4.0 mm, height 2.6 mm, registration number AM P97820.

Allotype. Female deposited in Australian Museum, Sydney, length 4.8 mm, height 2.9 mm, registration number AM P97821.

Paratypes:; two females 4.9 x 3.0 mm, 4.4 x 3.0 mm, registration number AM P97822.

Other material. Northern Territory, few females and juveniles, Kata Tjuta, Valley of the Winds, small rocky pond, 25o 17’ 22.3”S, 130o 44’ 18.8”E, 24 Sept 2009, J. Powling, AM P97823; eleven females, Uluru (top of Ayers Rock) 25o 20’ 39.4’S, 131o 02’ 32.8”E, 4 July 1991, D. Carter, SAM C8459; five females, Uluru, shallow gnamma on top, 25o 20’ 39.4’S, 131o 02’ 32.8”E, 22 Dec 1996, unknown collector, AM P49190.

Diagnosis. Egg with about 28 elongated polygons, each with an uneven surface and microporous. Male with a triangular rostrum, a little smaller than the ocular tubercle. Male with about 8 telsonic spines, irregular in spacing and size. Both sexes with about 6–7 short cercopod setae (ie. about 1x cercopod diameter). Female with 9–10 telsonic spines irregular in spacing and size.

Description. Eggs ( Fig 9 H,I)153 Μm diameter, range 148 to 164 Μm (n = 5). About 28 elongated polygons with low lateral ridges, weakly rudentiform, and a long narrow central groove. Polygons about 60 ìm by 40 ìm. Uneven surface with a tendency to be knobbly especially adjacent to the grooves. On enlargement surface with numerous small holes each within its own minipolygon. Some eggs (not included in the 5 measured ones) appear immature in that the main polygons are indeterminate, but still a groove is present and the surface somewhat knobbly.

Male. Head ( Fig 17 C) with a prominent ocular tubercle with a compound eye occupying most (ca 80%) of it. Rostrum an equilateral triangle a little smaller than the ocular tubercle. Ocellus small (ca one quarter size of eye) located in dorsal base of rostrum. Dorsal organ posterior to the eye by about its height, pedunculate and with a flattened apex at a 45o angle to the peduncle and of similar height as the ocular tubercle.

First antennae a little longer than the peduncle of the second antennae and with about 7 lobes each with numerous tiny sensory setae.

Second antennae with a spinose peduncle and each flagella with about 7 antennomeres, dorsally with 1–4 spines and ventrally with 1–5 long setae. The spines tend to be more numerous on basal antennomeres and the setae more numerous on distal antennomeres. Basal antennomeres with strong reticular markings.

Carapace ( Fig 17 A) elongated oval, pellucid and with little indication of growth lines. Dorsal edge slightly convex. Adductor muscle lying at about 45o to horizontal body axis. No growth lines visible.

Thoracopods. Eighteen pairs, the first two modified as claspers ( Fig 17 G). Both claspers with palm trapezoid but with a swelling mediodistally at the base of the apical knob. This knob spherical with apex with thick blunt denticles mediodistally and spines laterodistally and a small palp laterally. Finger arcuate with a rounded apex bearing a suctorial disc apicoventrally and many rounded pits apicodorsally. Long palp inserted on the apical edge of the palm, about 1.5 times as long as the palm in clasper I and twice as long a clasper II, two segmented and with 4–5 stout setae at the segmental junction and many small setae terminally.

Other thoracopods of typical structure for Eulimnadia , decreasing in size and complexity posteriorly.

Trunk. Dorsal surface with 1–3 spines posteriorly on at least each of the posterior eigth trunk segments.

Telson ( Fig 17 E) with 9 pairs of dorsal spines, the first much larger than the next three well spaced small spines, followed by 4 increasingly larger spines. Caudal filaments originating from a mound a little higher than the dorsal floor of the telson and at spine 2. Dorsal floor posterior to the mound sloping away to the cercopod base. Cercopods subequal in length to the telson dorsum, the basal 75% bearing 6 short and well spaced setae, length subequal to cercopod diameter, followed by a short spine and then rapid thinning to an acute apex. Setae two segmented and well feathered. Narrowing apical quarter of cercopod with a cirrus of many small denticles mediodorsally. Prominent spiniform projection beneath the cercopods at the ventroposterior corner of the telson.

Hermaphrodite. Head ( Fig 17 D) with ocular tubercle prominent, with compound eye occupying most (ca 80%) of it. Rostrum a smooth bulge at about an angle of 160o to the frons and with the centrobasal part occupied by an ocellus, about one third the size of the eye. Dorsal organ posterior to the eye as in male. First antennae a little shorter than the peduncle of the second antennae, with 5 lobes each with many short sensory setae.

Second antennae as in male.

Carapace ( Fig 17 B) elongated oval, pellucid and with little indication of growth lines. Dorsal edge distinctly convex. Adductor muscle lying at about 45o to horizontal body axis.

Thoracopods. Eighteen of typical Eulimnadia structure.

Trunk dorsum with 3–9 setae terminally, these setae few, short and stout on last few segments, numerous and longer on segments 8–15, and hardly any setae on anterior trunk segments 1–7.

Telson ( Fig 17 F) as in male, but with 11 dorsal spines spaced and sized largely as in the male. Cercopod with 7 short and spaced setae, but otherwise as in male.

Variability. One hermaphrodite was seen with 8 antennomeres, instead of 7. Telsonic spines vary between 8 and 10 in males and between 9 and 11 in females. The caudal filaments are inserted on either side of the second spine, or right at its position. Cercopod setae vary from 6–8 in males and 7–9 in females, but are never long, i.e. longer than diameter of cercopod.

Comments. This species lives in a distinct habitat, the gnammas on top of Uluru and small pools associated with valley seeps on Kata Tjuta. It is likely to live in gnammas on top of Kata Tjuta, but these are inaccessible. The claspers, rostrum, antenna 1 and antenna 2 are not distinctive (except perhaps the antennomeres numbering only 7), but the low number (<10) of telsonic spines and only 6–7 widely spaced cercopod setae are distinctive. The egg is similar to that of E. pinocchionis sp. nov. in that polygons are shallow and with ropey edges and rough floors, but the later has about 97 polygons as against about 28 in E. uluruensis and are far more regular in shape. The reticular markings on the basal antennomeres are not always distinct, but this in the only species in the present series with them.

Only one male has ever been collected, but many hermaprodites, indicating an androdioecious mode of reproduction (Weeks et al., 2008).

Distribution. Restricted to rock pools of Uluru and Kata Tjuta in central Australia.

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 17. Eulimnadia uluruensis sp. nov. Uluru, NT.. A, male carapace; B, female carapace; C, male head and antennae; D, female head; E, male telson; F, female telson; G, male clasper. Scale bars 1 mm.