Limnadopsis birchii ( Baird, 1860 )

Timms, Brian V., 2009, A Revision of the Australian Endemic Clam Shrimp Genus Limnadopsis Spencer & Hall (Crustacea: Branchiopoda: Spinicaudata: Limnadiidae), Records of the Australian Museum 61 (1), pp. 49-72 : 52-55

Limnadopsis birchii ( Baird, 1860)

Figs. 2A , 3 , 4A , 5A,B

Estheria birchii Baird, 1860: 392–393 , pl. 72, fig. 1a–e; Grube, 1865: 234 (list); Simon, 1886: 453 (list).

Limnadopsis squirei Spencer & Hall, 1896: 239–241 , pl. 21, fig. 15, pl. 22, figs. 16–19; Wolf, 1911: 254 (list); Dakin, 1914: 295 (list); Henry, 1924: 132 (key).

Limnadopsis birchii .— Sayce, 1903: 249–250; Wolf, 1911: 254 (list); Dakin, 1914: 295 (list); Henry, 1924: 121–122 (list), 132; Brtek, 1997: 58 (list); Richter & Timms, 2005: 349.

Limnadiopsis brichii .— Daday, 1925: 177–181, fig. 122 (misspelling); Novojilov, 1958: 104–105, fig. 13 (misspelling).

Types. None designated or available, but some material available for L. squirei .

Remarks on type material. Baird’s (1860) material cannot be located, but some of the original material used by Spencer & Hall (1896) for their description of L. squirei (reported by the authors to comprise six specimens in spirit and over a 100 dried carapaces) is available. The NMV has four of the dried carapaces from central Australia which I regard as syntypes (NMV J53349 ), and also a few specimens in alcohol (NMV J54042 ), but there is uncertainly over the latter’s origin so I do not treat them as syntypes.

Other material. New South Wales:23, 1♀, NW of Bourke, Tredega Station, Lake Muella , 29°31'S 144°53'E, 6.xii.1999, B. V. Timms, AM P76800; 13 , 12♀, NW of Bourke, Bloodwood Station, Last Swamp , 29°29'S. 144°49'E ,

6.ii.1999, B. V. Timms, AM P76801; 5 empty carapaces, 130 km NW of Bourke, Bloodwood Station , 29.6°S 144.9°E , 26.vi.1999, S. Richter, AM P55649; 43, 7♀, 11 km N of White Cliffs , 30.7°S 143.1°E , no date, A.B. Chislett, AM P11456, 83 , 5♀, W of Cooma, Coolringdon Station, Fat Hen Lake , 36°16'S 148°56'E , 19.iv.1992. B. V. Timms AM P76802. Queensland: near Windorah, Carranya Station , claypan, 25°18'S 142°12'E , 6.iii.1977, J. Covacevich, QM W7254 ; near Roma, Suva Station, Bore Hole , 26°21'S 148°28'E , 6.iii.1977, J. Covacevich, QM W10953; 23, E of Thargomindah, Bindegolly Lake , 28°04'S 144°10'E , 9.ii.2007, M. Handley, QM W28364; 73, 14♀, Cunnamulla , 28.1°S 145.7°E , iii.1947, N. Geary, AM P11794; 16 individuals, near Hungerford, Currawinya National Park , between Lakes Yumberarra and South Kaponyee, creek pool, 28°53'S 144°20'E , 7.xii.1999, B. V. Timms, QM W28365; 43, near Hungerford , Currawinya National Park, Lake South Kaponyee, 28°52'S 144°20'E , 7.xii.1999, B. V. Timms, QM W28366; 23 individuals, near Hungerford, Currawinya National Park , “ CA ” clay pan, 28°52'S 144°20'E , 3.ii.1998, B. V. Timms, QM W28368; 1♀, SW of Diranbandi, Culgoa Floodplain National Park, East Burrenbah Section , 28°51'S 146°48'E , 14.xii.1999, C. Eddie, QM W28368. Northern Territory: 13, 10♀, 3 empty carapaces, Tanami Desert Sanctuary, east of Mount Ptilotus , claypan, 20°12'S 130°12'E , no date, H. Cogger, AM P14934. South Australia: 13, 2♀, N of Oodnadatta, Hamilton Station , 17.iii.1976, Mr Cekic, SAM C6353 ; N of Oodnadatta, Stevenson Ck, no date but earlier than 1897, Prof Spencer, NMV J54042 ; N of Oodnadatta, Macumba Ck, no details, NMV J53361 ; Macumba & Stevenson Cks, Spencer & Hall?, NMV J53995 ; Cameron Corner , cane grass swamp , 22.iv.1979, M.G. & A.H. Corrick, NMV J54001 ; 43, one indeterminate individual, near South Gap homestead, South Gap Creek , i.2007, J & K Sanderson, SAM C3652 . Western Australia: Upper Fortescue River, Mulga Downs Station, near Bunji Well , muddy pool, 22°10'S 118°26'E , 3.vii.1970, M.H. Shepherd, WAM C39325; Barrow Is. , 20°52'S 115°24'E , 18.iv.1976, C. Butler, WAM C39326; near Leinster , mine site, waterhole in dry creek bed , 20.iii.2001, G. Walker, WAM C28201; 120 km NNE of Broome, “ Bungnaduk ” , 8.ii.1989, J. Martin, WAM C39327; 1♀, NE of Carnarvon, Mardathuna Station, Bulgra pool, 24°24'S 114°33'E , 21.iii.1995, S.A. Halse, WAM C39328; 13, 7♀, NE of Carnarvon, Cooralya Station, Bluebush Bore Swamp , 24°28'S 114°18'E , 21.iii.1995, S.A. Halse, WAM C39329; 3♀, near Laverton , 22 km northwest on highway, samphire swamp, 28°36'S 122°13'E , 17.ii.2003, B. Datson, WAM C39330 .

Distribution. Australia-wide (but not recorded from Victoria or Tasmania), generally in the arid and semiarid inland.

Comments. This large distinctive species was first described by Baird in 1860 as Estheria birchii on the basis of a female collected in floodplain lagoons of the Namoi (misspelt Wamoi) River, NSW. The description is poor, but there is no doubt that what is today known as L. birchii was the subject. In 1896 Spencer and Hall published a detailed description of a species from central Australia that they placed in a new genus and called Limnadopsis squirei . Sayce (1903) realized that Baird’s E. birchii and the new L. squirei were synonymous. Since then, many authors (see synonymy list above) have mentioned the species, perhaps with new distribution records, but without adding to its known features.

Spencer & Hall’s (1896) description is almost adequate, but it lacks a description of the thoracopods. The thoracopods of basic structure noted for spinicaudatans ( McLaughlin, 1980; Alonso, 1996; Ferreri & Grygier, 2003). The male third thoracopod ( Fig. 4A ) with five endites on medial surface, each with differing numbers of setae (Ist with c. 20; 2nd with c. 40; 3rd with c. 30, 4th with c. 30; 5th with c. 25). These setae not evenly distributed but sparse in middle region of the endite and crowded at proximal end, more so on the 4th and 5th endites than on others. Fifth endite elongated, and similar in shape to finger-like endopod. Fifth endite bearing a one-segmented palp slightly longer than endite. Exopod bipolar with finger-like extensions distally (termed a flabellum by McLaughlin, 1980) and proximally. Endopod clothed with c. 60 setae and exopod with more than 100 setae. All setae two-segmented and differing slightly as to degree of feathering—exopod and endopod setae fully feathered, most endite setae with proximal segment sparsely feathered and distal segment densely feathered, and setae of the 5th endite naked. Oval-shaped, naked epipodite lying between proximal lobe of exopod and the main axis carrying endites. Other thoracopods essentially similar to third, but without palp on 5th endite and with slightly differing proportions of parts, particularly of epipodite. Female thoracopods similar to those of males but without palp on 5th endite, and ninth and tenth pairs with projections of exopod on which eggs carried.

Eggs ( Fig. 5A,B ) round, about 172 µm in diameter (range 162–186 µm, n = 10), with parallel groups of ridges and deep clefts arranged around surface. No major differences in this respect between eastern and western populations ( Fig. 5A,B ) studied.

Variability. Limnadopsis birchii is more variable than indicated by Spencer & Hall (1896). The carapace shape ( Figs. 2A , 3A ) is broadly oval, but usually with a distinct anterodorsal angle of about 120°, and a convex dorsal margin that is slightly depressed anterior of the umbo. The dorsal margin, posterior of the embryonic valve, bears many asymmetrical carinae (= “backwardly directed serrations” of Spencer & Hall 1896), the posterior edges of which are continuous with the growth lines, and which increase in size posteriorly till the last one (usually) protrudes beyond the posterodorsal corner. In many populations and individuals, however, these outgrowths are irregular and in some cases absent altogether. Similar carinae exist in L. tatei , but it is distinctive of L. birchii that invariably the protrusion of each carinae beyond the hinge line begins well forward in the previous growth area, almost back to the second preceding growth line. Generally there are about 12–13 growth lines, with a range of 11–15 mentioned by Spencer & Hall (1896), and 10–17 in the present material examined. Enormous carapace sizes of up to 27 mm long and 20 mm high were mentioned by Spencer & Hall (1896); slightly larger ones (to 29 mm) were observed in the present material and also relatively small ones of 18 mm (apparently adults). The length:depth (L:D) ratio is usually c. 1.5. Often females are slightly bigger than males, but otherwise both sexes are similarly shaped.

Spencer & Hall’s (1896) description of the head and rostrum ( Fig. 3B ) is a little different from that observed in the present material. While in males, the rostrum is at right angles to, and anterior of the ocular tubercle, there is no sharp angle in the cephalic profile between them, as in most other species of Limnadopsis , but an even curvature. The rostrum is generally about equal in length and basal width, and its apex is rounded and slightly curved ventrally. In females the rostrum ( Fig. 3G ) is shaped like an isosceles triangle with its short axis at right angles to the head. The ocular tubercle is typically longer than wide, a shape not observed in other species of Limnadopsis .

The first antenna was well characterized by Spencer & Hall (1896). In males it is longer than the peduncle of the second antenna, and in females equally as long as the latter. Spencer & Hall (1896) mentioned 16 lobules in males, but the mean in the present material is 12 ( Fig. 3D ), with a range of 10–15. The second antennae are essentially as described by Spencer & Hall (1896), with a peduncle of 11 segments (12 in most of the present material), and 2 flagellae of about 18 flagellomeres each. Most noticeable in the present material is the large number (ca 12) of dorsal spines on most of these flagellomeres ( Fig. 3E ), compared to fewer than 10 in other species of Limnadopsis .

All specimens have 32 pairs of thoracopods, 6–8 more than in other species of Limnadopsis . The dorsoposterior armature on the most posterior thoracic segments, not recorded by Spencer & Hall (1896), is variable but generally consists of 3–5 spines each on the last 7–9 segments, these being preceded by 2–3 segments with both a few spines and a few setae, then another 7–10 segments with setae, the number of which decreases anteriorly in number from about 10 per segment in females, and about 5 in males, to single one. The claspers of the male ( Fig. 3F ) are of standard spinicaudatan structure ( Fryer, 1987), with almost no macroscopic variation between populations. The asymmetrical protrusion on the anterior surface of the hand is relatively small and on the hand’s proximal half. The spine on the apex of the movable finger may be single and stout, or multiple (2–4) and thin; the palp of the movable finger in the second clasper is longer than usual, being at least 1.75 to 2 times the length of the hand. Concerning the telson ( Fig. 3C ), Spencer & Hall (1896) mentioned that there are about 50 dorsal spines (= denticles) in each row (cf. their fig. 19), and a pair of telsonic filaments at about one quarter of its length. They described the dorsal surface curved to form a shallow S-bend, and a curved, movable caudal claw bearing a “large number of plumose setae” proximally with the distal part the dorsal edge finely setose. In the present material the mean number of dorsal telson spines in each row is indeed about 50 (range 48–55), but rarely do they increase in size posteriorly as Spencer & Hall (1896) claimed. This number is more than twice that of other species of Limnadopsis ; furthermore the most anterior spine is little bigger than the next few, as opposed to the situation in most other species of Limnadopsis in which it is at least 1.5 times larger. The shallow S-bend (convex anteriorly, concave posteriorly) of the dorsal surface of the telson is present in most specimens examined, but in some the dorsal surface is almost straight. The caudal claw is evenly curved, i.e. the proximal portion is not straight as in most other species of Limnadopsis . It bears about 10–12 long setae (longer than width of the claw), followed in sequence by about 12–15 spines on the middle section of the caudal claw, and then the fine denticles of Spencer & Hall (1896) on the distal quarter. The most distal of the spines is almost always the largest and thickest.

Figures

Fig. 2. Photographs of whole specimens of species of Limnadopsis. (A) L. birchii; (B) L. tatei; (C) L. parvispinus; (D) L. minuta; (E) L. multilineata; (F) L. occidentalis; (G) L. paradoxa; (H) L. pilbarensis. Scale bars 5 mm.

Fig. 3. Limnadopsis birchii (Baird), Bloodwood Station, via Bourke, NSW. Male: (A) carapace; (B) head; (C) telson; (D) antennule; (E) a middle flagellomere of second antenna; (F) second clasper. Female: (G) head. For clarity some growth lines of the carapace are incompletely shown anterior to umbo. Scale bars 1 mm.

Fig. 4. Third thoracopods of males of (A) L. birchii; (B) L. tatei; (C) L. parvispinus; and (D) L. paradoxa n.sp. A few of the numerous setae (see text), and details of the major types of setae are shown only for L. birchii. Scale bars 1 mm.

Fig. 5. SEMs of eggs. (A) Limnadopsis birchii, Twin Pans, Currawinya National Park, Qld; (B) L. birchii, Bluebush Bore Swamp, via Carnarvon, WA; (C) L. multilineata, Mitchell River Falls, Kimberley, WA; (D) L. tatei, Bloodwood Station, Paroo; (E) L. tatei, near Laverton, WA; (F) L. pilbarensis, Chichester Range, WA; (G) L. parvispinus, Bloodwood Station, via Bourke, NSW; (H) L. parvispinus, Coolringdon Station, via Cooma, NSW; (J) L. occidentalis, Boolathana Station, via Carnarvon, WA; (K) L. paradoxa, Sieda Farm, Grass Patch, WA; (L) L. paradoxa, East Lake Bryde, via Newdegate, WA; (M) L. minuta, Keep River National Park, NT. Scale bars 50 µm.