Paralimnadia ammolophos, Timms, Brian V., 2016

Timms, Brian V., 2016, A review of the Australian endemic clam shrimp, Paralimnadia Sars 1896 (Crustacea: Branchiopoda: Spinicaudata), Zootaxa 4161 (4), pp. 451-508 : 471-474

Paralimnadia ammolophos n. sp.

( Figs. 4 , 11 , 12 )

Etymology. Since this species is found in coastal sanddune pools, its specific epithet commemorates this by using the Greek word for sanddune, ‘ammolophos’.

Type material. Holotype: AM P99004, male, length 5.1 mm, height 3.2 mm, Brooms Head , pond among dunes on the headland, 29°36’47.9”S, 153°20’18.6”E, 19 December 1983, BVT . Allotype: AM P99005, female, length 5.5 mm, height 3.6 mm, collected with holotype. Paratypes: AM P99006, 2 males, length 5.3 mm, height 3.5 mm, length 6.0 mm height 4.0 mm; 2 females, length 6.4 mm, height 4.1 mm, length 7.0 mm, height 4.7 mm, Shelley Headland , New South Wales, pond in dunes, 29°31’ 52.8”S, 153°21’12.8”E, 14 July 2015, BVT .

Other material examined. New South Wales: 5 males, 5 females, Shelley Headland, pond in dunes, 29°31’52.8”S, 153°21’12.8”E, 14 July 2015, BVT, AM P99007 ; 3 males, 7 females, Brooms Head , pond among dunes on the headland, 29°36’47.9”S, 153°20’ 18.6”E, 19 December 1983, BVT, AM P99008 ; Brooms Head south beach, swamp in frontal dunes, 29°37’34.3”S, 153°19’37.7”E, 18 March 1977, BVT, 3 males, 5 females, AM P99009 .

Description. Male. Head ( Fig. 12 B) with ocular tubercle prominent, the compound eye occupying about 50% of its diameter. Rostrum protruding a little more than the ocular tubercle and at right angles from its base, triangular in shape, and with a blunt apex. Ocellus slightly smaller than compound eye and lying at base of rostrum. Dorsal organ posterior to eye by about half its height, pedunculate and asymmetrical and not quite as high as ocular tubercle.

First antennae ( Fig. 12 B) almost twice the length of peduncle of second antennae, and with seven lobes, each with numerous short sensory setae. Second antennae ( Fig. 12 E) with spinose peduncle and dorsal flagellum with 10 antennomeres; ventral flagellum with 12 antennomeres; dorsally with 1–3 short spines and ventrally with 1–5 longer setae. Distal antennomeres with minimal spines and maximal setae.

Carapace ( Fig. 12 A) elongated oval, opaque brown and darker dorsally, with hardly any indication of growth lines. Adductor muscle scar at about 45° to carapace long axis, only visible when animal removed from carapace.

Thoracopods. Eighteen pairs of thoracopods. Claspers ( Fig. 12 D) with palm trapezoidal, with distinct rounded expansion distomedially. Apical club spherical with gripping area bearing many stout spines directedmedially.Small palp with many short, thin spines apically. Finger arcuate with a blunt apex and many rounded pits ventrally. Long palp of claspers I and II inserted on apical edge of palm, with 3 palpomeres and 3 stout setae at first junction and many thin, limp setae on flattened palaform apices. Long palp of first clapser about 1.25 × length of palm and in second clasper, 2 × length. Other thoracopods of typical structure for Paralimnadia , decreasing is size and complexity posteriorly. Last ten segments dorsally with a short spine medially.

Telson ( Fig. 12 C) with spine rows bearing about 14 pairs of spines, with anteriormost spine about twice the size of next few, and penultimate spines a little longer than most spines. Spines with spinulae.Telsonic filaments originating from a mound a little higher than the dorsal floor of the telson positioned at about the fourth spine pair.

Dorsal floor of telson posterior to mound slopes steeply, then with slightly convex surface to base of cercopod. Cercopods almost as long as the posterior margin of telson, basal 50% hardly narrowing to small spine then rapid narrowing to acute apex. About 9 long (reaching large posteriormost spine of telson) setae on basal half and many tiny denticles dorsolaterally on apical half. Setae geniculate and plumose.Ventroposterior corner of telson rounded and hardly protruding.

Female. Head ( Fig. 12 G) with ocular tubercle prominent, with compound eye occupying about 50% of diameter. Rostrum a rounded prominent bulge, slightly less prominent than ocular tubercle and with middle basal part occupied by large ocellus, about 80% size of compound eye. Dorsal organ posterior to eye by about threequarters of its height, pedunculate and asymmetrical and not quite as high as ocular tubercle.

First antennae ( Fig. 12 G) a little shorter than peduncle of second antennae, with 3 small lobes each with many short sensory setae. Second antennae largely as in male, though dorsal flagellum with 11 rather than 10 antennomeres.

Carapace ( Fig. 12 F) as in male, though more vaulted dorsally.

Thoracopods. Seventeen pairs of thoracopods of typical Paralimnadia structure. Trunk dorsum with segments 1–9 inerm, segments 10–14 with 3–5 spines medioterminally and segments 15–17 with spine medioterminally. Thoracopods 9 and 10 with a long flabellum dorsally.

Telson ( Fig. 12 H) as in male, though with 19 pairs of posterior row spines, otherwise with cercopod similar.

Egg ( Fig. 11 A, B) broadly angular, mean diameter 232 µm (range 220–238 µm, n = 10). About 12 rounded, separated knobs protruding about 50 µm and each linked by up to 10 sharp, radiating ridges alternating with grooves about 60 µm long. Some grooves with tiny pits.

Variability. The relative size of the compound eye varies between specimens from about 40–70%; the same with the ocellus. The male rostrum is always triangular and slightly larger than the ocular tubercle. First antennal lobes vary from 6 to 9 and the antennomeres from 9–12, with the ventral flagellum usually with more than dorsal flabellum. Females may have 18 trunk segments as in males. Telsonic spines vary from 14–19, but the arrangement of the first about twice the following few, then the middle few the shortest and the last few of increasing length is apparently standard. The cercopod is the least variable component, with always 8–10 setae and a 50:50 division between the setae carrying base and narrowing denticulated distal portion.

Differential diagnosis. Many features such as relative length and shape of male rostrum, number of antenna I lobes, number and relative size of telsonic spines, size of projection at the mediodistal corner of the clasper hand and number of palpomers of the large palp of the clasper are shared in various combinations with other species. However, the egg of P. ammolophos n. sp. is unique with its knob shaped projections approximately 12 in number. Of those species with long cercopod setae ( P. bishop n. sp., P. flavia n. sp., P. queenlandicus n sp.), P. ammolophos n. sp. is the only one with <10 of uniform length. Other differences from P. bishopi n. sp., which live in a similar habitat, are given below.

Distribution and ecology. This species is apparently restricted to temporary rainfilled hollows in coastal dunes in northern New South Wales ( Fig. 4 ). These are slightly-moderately acidic ( pH ca. 5–6) and often humic ( Timms 1982). It could occur further north and south of this region as neither has been explored, but it has not been found further inland. It was common before the coastal dune country of northern New South Wales was mined for mineral sands in the 1960–80 s (author unpublished) but it now persists in a few sites not mined and then occurs only sporadically.

Figures

FIGURE 4. Map of Australia showing distributions of all species with insert of details of Sydney region, especially for sites of P. stanyleyana.

FIGURE 11. Scanning electron micrographs of eggs. A-B, Paralimnadia ammolophos n. sp., C, P. bishopi n. sp., D-F, P. flavia n. sp., G-H, P. hyposalina n. sp., I-J, P. monaro n. sp., K-L, P. montana n. sp. A from Brooms Head, NSW, AM P 99008; B from Shelly Beach, NSW, AM P 99007; C from Cape Bedford, Qld, AM P 99359; D from Radom Springs, NT, AM P 98911; E from Larrimah, NT, AM P 98999; F from near Kununurra, WA, WAM C 61749; G from Coomberdale, WA, WAM C 61751; H from Watheroo, WA, WAM C 61753; I from near Berridale, NSW, AM P 99011; J from Manderley Pool, NSW, AM P 47129; K from Glencoe Lagoon, NSW, AMP 99014; L from Emu Rk Tarn, NSW, AM P 47132. Scale bars 0.1 mm.

FIGURE 12. Paralimnadia ammolophos n. sp. A – E male from AM P 99004; A, carapace; B, head; C, telson; D, 2 nd clasper; E, 2 nd antenna; F – H female from AM P 99005; F, carapace; G, head; H, telson. Scale bars 1 mm.