Leydigia (Neoleydigia) cf. ipojucae Brehm, 1938

Kotov, Alexey A., 2009, A revision of Leydigia Kurz, 1875 (Anomopoda, Cladocera, Branchiopoda), and subgeneric differentiation within the genus, Zootaxa 2082 (1), pp. 1-84 : 63-68

X. Leydigia (Neoleydigia) cf. ipojucae Brehm, 1938

( Figs 338–375 )

Leydigia ipojucae Brehm, 1938, p. 102 –103, figs 9–10; Smirnov 1971, p. 463, fig. 580 (after Brehm, 1938)

? Elmoor-Loureiro 1998, p. 35; Elmoor-Loureiro 2000, Tab. 1.

Type locality. "Rio Ipojuca bei São Caetano. (Mun. São Caetano.)" There is a series of localities with this name in Brazil , but, most probably, samples were collected in the vicinity of São Caitano da Raposa (appr. 8º20'S, 36º06'W), Municipio São Caitano (or Caetano), State of Pernambuco, Brazil .

Type material. Apparently lost (see comments).

Material examined. Brazil. Rio Grande do Norte: 3 parth. ♀♀ from a reservoir in semiarid NE Brazil, hatched from dried mud by C. Crispim, tube AAK 1999-098 (06º12'03''S, 36º49'87''W) .

Diagnosis. Parthenogenetic female. Body subovoid, maximum height in middle, dorsal margin uniformly curved from tip of rostrum to completely smooth postero-dorsal angle; posterior margin significantly convex ( Fig. 338 ), in juveniles dorsum straight posteriorly and postero-dorsal angle evident ( Fig. 340 ). No coarse striation on valves. Fine striation on entire surface of valves and head shield very distinct ( Figs 342–343, 346 ). In anterior view, body moderately compressed laterally (less than in all abovementioned species), dorsum like rounded triangle in section ( Fig. 339 ). Head small, ocellus somewhat larger than eye. Head shield wide ( Fig. 341 ), PP = 7–8 IP, lateral head pores about 0.4 IP distance from midline, all head pores located in region without reticulation ( Figs 342–343 ). Labral keel triangular-ovoid, posterior margin with three groups of fine setules of moderate length, anterior margin with long fringe of setules from base to apex, 4 lateral groups of long, robust setules, projecting anteriorly behind marginal setules, plus several groups of shorter setules on sides of keel ( Figs 344–345 ). On valves, setae at middle of ventral margin with sparse, short setulation, their bases located exactly marginally, long setules between them. In posterior portion, these setae setulated significantly asymmetrically, setules on posterior side of each seta long and thickened, posteriormost seta long ( Fig. 348 ). Posterior to the last marginal seta, a row of submarginal setules on inner face of posterior margin, in region of postero-ventral angle, setules long and in continuous series; in medan and dorsal parts of posterior margin, setules located far from margin, and short; marginal membrane of minute 'setules' ( Fig. 349 ).

Postabdomen broad, subovoid, elongated ( Figs 350–352 ), preanal margin shorter than anus, 3–4 smooth projections in basal half ( Figs 353–354 ), preanal and postanal angles well defined, whole postanal margin from anus to basis of claws evenly arched, though very obtuse dorso-distal angle recongnisable. Postanal marginal denticles in numerous (more than 20) clusters, size increasing distally in each cluster ( Figs 355–356 ). 7–10 fascicles of stout lateral setae, decreasing in size basally, normally 4–5 setae in each fascicle on distal portion or in middle, marginalmost setae of each fascicle significantly larger than rest, 2–3 times as long as second seta, next setae very fine, 17–23 fascicles of lateral setules on basal half of postanal and anal margin, setule size increasing gradually basally in each fascicle ( Fig. 357 ). Postabdominal claw approximately as long as preanal plus anal portion of postabdomen, slightly and evenly curved, 2 small setules at claw base, basal spine small, sometimes blunt, but normally present ( Fig. 358 ). On inner surface of claw, denticles in distal pecten robust ( Figs 359–360 ).

Antenna I thick, almost reaching tip of rostrum, with 4 transverse rows of long setules on anterior face, distalmost setules specially thick, no setules at tip ( Figs 361–362 ). Sensory seta 1/4 way from tip. Largest aesthetasc about half as long as appendage, all aesthetascs projecting behind tip of rostrum. Antenna II with 3 spine-like setules on first, and 2 spine-like setules on second endopod segment ( Fig. 363 ). Apical swimming setae with basal and distal segments bilaterally armed with fine, long setules from base to tip, no chitinous insertions within distal segments ( Fig. 364 ). Basal lateral seta particularly short, distal lateral seta shorter than apical setae.

Trunk limb I ( Fig. 365 ) ODL large, elongated, narrowing distally, without setules, with a long seta with distal segment unilaterally armed with short, sparse setules. IDL with 2 medial clusters of minute setules, and 3 marginal clusters of stout setules: in basal and middle clusters setules of medium size, short in distalmost cluster, first seta smallest, with several short setules distally; second and third setae equal in length and setulation ( Fig. 366 ), endite 3 with long, stiff seta 1, armed with long, fine setules and small receptor near its base, endite 2 with two setae e–f subequal in length and seta 2 rudimentary, naked, with a hillock in position of sensillum near base, endite 1 with rudimentary seta 3. Two ejector hooks of unequal size. Trunk limb II with exopodite ovoid, small, supplied with a tuft of short, robust setules ( Fig. 367 ). Distalmost scraper 1 with fully setulated basal segment, on distal lobe with basal tuft of long setules, four setae in distal armature of gnathobase ( Fig. 368 ). Limb III ( Fig. 369 ), exopodite subquadrabgular, with rudimentary lateral seta 3, and two distal setae 1–2, seta 2 with distal segment armed bilaterally with short setules of different lengths ( Fig. 370 ), seta 1 with fully setulated basal segment; seta 1of distal endite with robust denticles ( Fig. 371 ), filter plate with distalmost and basalmost setae shorter than rest. Trunk limb IV exopodite with six setae, setae 2 relatively long, seta 1 short, but also with long, fine setules ( Fig. 372 ), on inner portion of limb, seta 2 with robust setules, in filter plate distalmost seta with inflated basal segment and fully setulated, all setae with inflated tips ( Fig. 373 ). Trunk limb V with subovoid exopodite, on inner face of limb two setulated setae, basalmost markedly slender, longer and supplied with longer setules ( Figs 374–375 ). Distal armature of gnathobase as a setulated lobe, two setae of 'filter plate' particularly small.

Ephippial female, male. Unknown.

Size. Juvenile and adult parthenogenetic females from Rio Grande do Norte 510–900 µm (n = 3), range clearly under-estimated.

Differential diagnosis. Setules in lateral groups on the labral keel longer and more robust than those on the anterior keel margin in L. ipojucae and are unique within the genus. Among the acanthocercoides -group, this is the only species with smooth hillocks on the preanal margin of the postabdomen. Also, only in this species and L. striatadoes scraper 1 on limb II have a setulated base.

Taxonomical comments. Although the description of Brehm (1938) occupied a page of text, it was inadequate. His reference to an 'identical' form from Argentina in Richard's (1897) article is not convincing. We can extract only the following information about Brehm’s species from his text: (1) body shape similar to that of L. propinqua Sars, 1903 (I am sure that the author had no clear idea of the morphology of propinqua s. str.); (2) eye and ocellus of similar size; (3) valves with dots and small-scale striation; (4) five groups of long setules on vetral margin of labrum; (5) small basal spine on postabdominal claw; (6) each lateral fascicle on postabdomen consists of a long seta, and a series of small, fine setules. In the author’s illustration it is shown, that (7) the postero-dorsal angle is ill-defined in L. ipojucae . Four transverse rows of setules, described in detail by Brehm, are present in all species of the genus.

Brehm’s distinction of L. ipojuca from L. propinqua was based on dubious characters. The latter is a distinctive species, which has several other traits that are unique within the genus. Leydigia ipojucae is an acanthocercoides -like species, described earlier than other tropical acanthocercoides -like forms, L. ciliata Gauthier, 1939 and L. striata Birabén, 1939 , which are the most common tropical species of Leydigia ( Frey 1982; Smirnov & Timms 1983; Dumont et al. 1984; Kotov et al. 2003b).

I think that Brehm explained incorrectly the armature of the labrum in his species. In L. ipojucae the long and stout lateral setules project behind the margin, while the marginal setae are finer and significantly shorter, and were, to my mind, missed by him. I have not seen in original samples or previous publications, any other species from anywhere in the world with groups of stout 'spines' on the labrum, which setulation is one of the most important traits for the systematics of Leydigia . The bulk of earlier published descriptions of South American forms dealt with L. striata , which is relatively common there ( Birabén 1939; Kotov et al. 2003b). Also, L. schubarti Brehm and Thomsen, 1936 was described from this continent, but it lacks these setules.

Among the many difficulties in understanding Brehm’s taxa is the fact that he did not specify types. Few Brehm's specimen tubes survived in the collection of Vienna University, in disorder (H. Loeffler, personal communication through H. J. Dumont). No types are present here, but there remains a slight chance of finding some original samples with Brehm’s species, that colud be used for the selection of lectotypes. This is a problem for the future selection of neotypes.

Distribution. A few localities in Brazil.

Figures

FIGURES 338–349. Leydigia cf. ipojucae, parthenogenetic female from a reservoir in semiarid NE Brazil, Rio Grande do Norte, hatched from dried mud by C. Crispim. 338–339. Adult in lateral and anterior view. 340. Juvenile. 341–343. Head shield and dorsal head pores of adult. 344–345. Labrum. 346–349. Reticulation of valves, armature of its ventral, postero-ventral and posterior margin. Scale bar denotes 100 µm.

FIGURES 350–364. Leydigia cf. ipojucae, parthenogenetic female from a reservoir in semiarid NE Brazil. 350. Postabdomen of juvenile. 351–352. Postabdomen of adult. 353–354. Its preanal margin. 355–356. Armature of its postanal margin. 357. Series of setules at basal portion of preanal margin, cross section. 358–360. Distal portion of postabdomen, postabdominal claw in inner view and denticle in middle of claw on its posterior face. 361–362. Antenna I. 363–364. Antenna II and its apical swimming seta. Scale bar denotes 100 µm.

FIGURES 365–375. Leydigia cf. ipojucae, limbs of parthenogenetic female from a reservoir in semiarid NE Brazil. 365–366. Limb I and its distal portion. 367–368. Limb II and its gnathobase. 369–371. Limb III, largest seta of its exopodite, and inner limb portion. 372–373. Limb IV and its inner portion. 374–375. Limb V and its gnathobase. Scale bar denotes 100 µm.