Limnadopsis paratatei Schwentner, Timms & Richter, 2012, sp. nov.
Creators: name: Schwentner, Martin
name: Timms, Brian V.
name: Richter, Stefan
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Branchiopoda
Diplostraca
Limnadiidae
Limnadopsis
Limnadopsis paratatei

description: Limnadopsis paratatei sp. nov.
(Figs. 1 e, f, 5, 6, 7)
Limnadopsis cf. tatei ‘Carter’s’: by Schwentner et al. 2011
Etymology: The name of this species is based on its morphological similarity to Limnadopsis tatei. Type locality: New South Wales, Muella Station, small lake on East Boundary, north side of road, 29°31'38.5''S, 145°00'43.7''E, 20.ii.2010.
Type material: Holotype 3 AM P.86414 (GenBank JN698589); allotype Ƥ AM P.86411 (GenBank JN698586); paratypes 73 3Ƥ (AM P.86417, AM P.86418, AM P.86392 - AM P.86396, P.86410, AM P.86412, AM P.86413; GenBank JN698592, JN698593, JN698567 - JN698571, JN698585, JN698587, JN698588).
Further material examined. New South Wales: 53, 2Ƥ (AM P.84206 - AM P.84209, AM P.86389 – AM P.86391, GenBank HQ717784 - HQ717787, JN698564 - JN698566), Muella Station, Carters Swamp, 29°25'59.6''S, 144°58'58.8''E, 31.iii.2009; 13, 3Ƥ (AM P.86415, AM P.86416, AM P.86400, AM P.86401, Gen- Bank JN698590, JN698591, JN698575, JN698576), Muella Station, Lismore Bore, 29°31'50.7''S, 144°59'28.1''E; 13, 4Ƥ (AM P.86419, AM P.86420, AM P.86397 - AM P.86399, GenBank JN698594, JN698595, JN698572 - JN698574), Muella Station, small lake on East Boundary, south side of road, 29°31'54.1''S, 145°01'02.4''E, 20.ii.2010; 53 (AM P.84210, AM P.84211, AM P.86386 - AM P.86388, GenBank HQ717788, HQ717789, JN698561 - JN698563), Rosedale Station, grassy pool north of Yantabulla, 29°19'04.8''S, 145°00'31.5''E, 20.i.2010. Queensland: 13, 2Ƥ (AM P.86402 - AM P.86404, GenBank JN698577 - JN698579), swamp near Thargomindah Station, 28°03'12.5''S, 143°47'11.5''E, 26.ii.2011; 43, 1Ƥ (AM P.86405 - AM P.86409, GenBank JN698580 - JN698584), 84 km south of Thargomindah, floodout of dam, 28°39'46.7''S, 143°48'40.8''E, 26.ii.2011.
Description.
Male (Holotype, AM P.86414) (Fig. 1 e, 5 a, b)
Carapace. Length 9.0 mm, height 5.2mm, length/height ratio 1.73 (Fig. 1 e). Seventeen well-marked growth lines, regularly arranged, with distance between growth lines increasing only slightly towards ventral margin, outer two growth lines crowded together at carapace margin, most growth lines extending dorsally into well-expressed dorsal serration with each outgrowth being small. Dorsal margin straight with depression before umbo, anterior margin convexly rounded, anterior-dorsal corner ~120°, ventral margin evenly rounded; posterior margin convexly rounded and extending as far as dorso-postrior corner, the latter extending into small spine.
Head. Mound containing the eye rounded and protruding, angle between eye-bulge and rostrum ~110° (Fig. 5 a). Rostrum elongated and bent posteriorly. Frontal organ pyriform and situated halfway between posterior margin of head and eye-bulge. First antenna with nine lobes (Fig. 5 a) reaching first antennomere of second antenna. Peduncle of second antenna with ten discernable segments, each covered in a row of setae and spines, both rami of second antenna with 14 antennomeres.
Trunk composed of 25 segments, decreasing in size posteriorly. First ten segments without dorsal armature, next eight segments with long setae, then six segments with small spines and last segment without dorsal armature. Claspers and thoracopods (based on male paratype, AM P.86395) exhibit same general structure as other spinicaudatan species (Olesen et al., 1996; Timms 2009), claspers bearing a small rounded tumidity in the proximal region of the main hand (Fig. 5 e), third thoracopod with five endites and endopod (or endite 6) on the inner margin and elongated exopod and enlarged (Fig. 5 f), oval epipod on the outer margin, fifth endite remarkably enlarged, terminating in a palp without setae.
Telson bearing 20 spines on each dorsal ridgeline, first spine larger than following spines, these irregularly sized and spaced (Fig. 5 b). Last spine greatly enlarged with the three preceding spines originating at its base; large spine on right side of telson bent at approximately 90°, that on left side nearly straight. Filaments inserted between fourth and fifth spine.
Furca. Each ramus bearing eight small setae on proximal third, followed by three spines with first two smaller and closer to setae than last spine (Fig. 5 b). Distal third of each ramus covered in small denticles. Proximal two-thirds of each ramus straight, distal third bent dorsally at about 45°. No spine or protrusion beneath the basal articulation.
Female (Allotype, AM P.86411) (Fig. 1 f, 5 c, d)
Carapace. Length 9.2 mm, height 5.4 mm, length/height ratio 1.7 (Fig. 1 f). Fourteen well-marked growth lines, regularly arranged, with distance between growth lines increasing only slightly towards ventral margin, most growth lines extend dorsally into dorsal serration, dorsal serration clearly expressed but small, as in male. Overall shape similar to male carapace, but dorsal margin posterior of umbo slightly convex instead of straight.
Head. Mound containing the eye, situated approximately midway between posterior margin of head and mound, latter protruding from head at an angle of ~130° to rostrum, rostrum short and triangular (Fig. 5 c). First antenna with seven lobes, just reaching first antennomere of second antenna. Peduncle of second antenna with eleven discernable segments, each with a row of setae and spines; anterior ramus with twelve antennomeres (distal antennomeres broken off), posterior ramus with 14 antennomeres.
Trunk composed of 25 segments, eight most anterior segments without dorsal armature, next ten segments with setae, then six segments with spines, and last segment only weakly expressed and spineless.
Telson very similar to male telson, bearing 20 spines along each dorsal ridgeline (Fig. 5 d). Only two smaller spines originating at base of posterior, enlarged spine. Filaments originate at the fifth spine.
Furca similar to male furca with each ramus bearing eight setae and two spines (Fig. 5 d).
Eggs. Round with a diameter of 165 mm (Fig. 7 c); surface covered in series of polygonal ridges (either pentagonal or hexagonal); the areas enclosed by the ridges bear an oval mound in their centre which is less elevated than the ridges.
Variability. The carapace of L. paratatei sp. nov. bears 10–18 distinct growth lines (Table 2), with males displaying slightly more growth lines than females on average (Fig. 1 e, f). In some specimens the outermost growth lines (up to five) are crowded together at the carapace margin. Several growth lines terminate in a weakly developed dorsal serration in which the ‘spines’ are always rather short. Posterior of the umbo, the dorsal margin is almost straight, only appearing slightly convex in rare cases. The dorso-posterior corner bears a small ‘spine’ (Fig. 7 g). The first antenna has five to twelve lobes (slightly more in males than in females) and generally reaches up to the second antennomere of the second antenna, but can be shorter. The rami of the second antenna consist of 11–17 antennomeres (Figs. 6 b, 7b). There are 24–25 trunk segments, the most posterior of which never bears any dorsal armature (Figs. 6 d, f, 7d, e). The telson bears 14–21 spines (Figs. 6 d, 7d). The first spine is always enlarged. The following spines are irregularly sized and spaced. The last spine is greatly enlarged and bears up to six of the preceding spines on its base (Fig. 7 f). In all males the large spine on the right side of the telson is bent at almost 90° whereas the spine on the left side of the telson is straighter (Fig. 6 d). In females the difference between the two telsonic sides is less pronounced, with both being fairly straight (Fig. 7 d). The furcal rami bear 5–14 setae which cover the first third or half of each ramus (Figs. 6 d, 7d). They are followed by one to five spines, the last of which is enlarged and inserts at about two-thirds of the length of the ramus. The last third of the furcal ramus is covered with numerous denticles. The tip of the movable finger of the male clasper features a single rounded scale with a ventral ledge which can be extended into a slender palp-like structure (Schwentner et al. 2011).
Genetic distances for COI within L. paratatei sp. nov. ranged from 0.0–1.7 % uncorrected p- distance to 0.0– 1.8 for K2P corrected distances (based on 43 specimens). No genetic structure was observed within its distribution range (Schwentner et al. submitted).
Distribution: L. paratatei sp. nov. has only been found to date at a few sites in the catchment areas of the Paroo River and the Bulloo River in the border region between Queensland and New South Wales.7
Remarks. Because of the close resemblance between L. paratatei sp. nov. and L. tatei, individuals of both species were hitherto all assumed to be L. tatei. The most obvious morphological differences include the dorsal serration on the carapace (always only weakly expressed in L. paratatei sp. nov.), the number of trunk segments (always fewer than 26 in L. paratatei), the number of spines on the telson (at least 14 in L. paratatei sp. nov.), the surface morphology of the eggs (polygonal ridges in L. paratatei sp. nov.) and the scale on the tip of the movable finger of the male claspers (round with a ledge in L. paratatei sp. nov.; see Table 2). Although other characters exhibit a greater overlap of states, differences between the species are notable. The dorsal margin of the carapace of L. paratatei sp. nov. is generally less convex (thus straighter) than in L. tatei and the dorso-posterior corner bears a smaller ‘spine’ (this may be correlated to the weaker development of the dorsal serration). Furthermore, the number of lobes on the first antennae and of setae on the furcal rami is lower in L. paratatei sp. nov. In addition, the setae generally occupy a smaller portion of the furcal rami in L. paratatei sp. nov. (usually less than half the length). The genetic distance between L. tatei and L. paratatei sp. nov. is 9.6–11.2% uncorrected p-distance and 10.7–12.1% K2P corrected distance for COI (Schwentner et al. 2011).
Although the two species co-occur in the area of the Paroo River catchment, inhabiting temporary water bodies only a few kilometers apart, they seem not to inhabit the same pools. Only one pool (Lismore Bore on Muella Station) harbored both species, but as only a single specimen of L. tatei was found there was no evidence of a permanent population of this species. Either their ecological needs differ or interspecific competition inhibits their cooccurrence within single pools. De Meester et al. (2002) coined the term Monopolization Hypothesis for the latter scenario. The presence of one species may inhibit the subsequent immigration of other species with very similar ecological needs through local adaptation and the monopolization of important resources.
description: Published as part of Schwentner, Martin, Timms, Brian V. & Richter, Stefan, 2012, Description of four new species of Limnadopsis from Australia (Crustacea: Branchiopoda: Spinicaudata), pp. 42-64 in Zootaxa 3315 on pages 49-53, DOI: 10.5281/zenodo.210812