Ilyocryptus cf. nevadensis Cervantes-Martínez, Gutiérrez-Aguirre & Elías-Gutiérrez, 2000

Kotov, Alexey A., Sinev, Artem Y. & Berrios, Viviana Lorena, 2010, The Cladocera (Crustacea: Branchiopoda) of six high altitude water bodies in the North Chilean Andes, with discussion of Andean endemism 2430, Zootaxa 2430 (1), pp. 1-66 : 15-18

Ilyocryptus cf. nevadensis Cervantes-Martínez, Gutiérrez-Aguirre & Elías-Gutiérrez, 2000

( Figures 5–6 )

? Ilyocryptus nevadensis Cervantes-Martínez, Gutiérrez-Aguirre et Elías-Gutiérrez 2000, p.313 –317, figs 1–26.

Material studied here. Two females from locality 2.

Diagnosis of Chilean specimens. Parthenogenetic female. Body triangular-rounded, high, cervical incision shallow, dorsal margin almost straight, postero-dorsal angle expressed ( Fig. 5A ). No lateral horns or other conspicous structures on valves ( Fig. 5B ). Moulting incomplete. Head small ( Figs. 5C–E ), with a distinct prominense where dorsal head pore opens, ocellus minute ( Fig. 5C ), mandibular articulation narrow ( Fig. 5E ). Labrum with a projected antero-ventral angle ( Fig. 5C ) and a pair of lateral projections in middle portion ( Fig. 5D ). Valves with fine reticulation, relatively large dots within cells well observable ( Fig. 5F ), setae in anterior bunch longer than the rest ( Fig. 5G ), while setae at postero-ventral portion not remarkably longer than other setae ( Fig. 5A ). Each seta in middle of ventral margin with specially long setules ( Fig. 5H ), each seta on posterior margin with markedly thick basal portion terminating in a single spine-like setule, and with finely setulated distal portion ( Fig. 5I ). Postabdomen high, height maximal in its middle; anus opens much closer to distal extremity than to base of postabdomen ( Fig. 5J ). Preanal teeth small, numerous, clustered, spaced regularly and standing approximately at right angles with margin ( Fig. 5K ), a gap between basalmost cluster and basis of postabdominal setae, as it was previously found in few other species ( Kotov & Timms, 1998). Rows of small setules near these teeth in basal part of postabdomen. Paired spines large and numerous, this row continuing along preanal margin up to its middle. Large lateral setae as long or even longer than paired spines ( Fig. 5L ), proximalmost seta located on preanal margin, not far from anus ( Fig. 5J ). Postabdominal claws relatively robust, no denticles in their distal or middle portions ( Fig. 5M ). Two spines on claw base, basalmost member longest. Setules ventrally on claw basal border long. Postabdominal setae long, densely setulated distally with relatively short hairs ( Fig. 5N ). Antenna I relatively short, proximal segment with a system of rounded hillocks and a terminal “crown” of conical projections ( Figs. 6A–B ). Distal segment with 4-5 rows of specially small denticles, distal end with a concentric row of hillocks. Two aesthetascs longer than others, and somewhat longer than half distal segment. Antenna II stout, distal burrowing spine almost reaching distal border of basal segment ( Fig. 6C ). Antennal branches robust, with well-developed denticles ( Fig. 6D ). Apical swimming setae with distal segments feathered along one side by setules of medium size and by minute setules along other side ( Fig. 6E ). Proximal and distal lateral swimming setae without hooks on their tips, with distal segments armed asymmetrically and with long setules on basal segments ( Fig. 6F ). Spine on second segment of exopod relatively long, reaching distal end of third segment ( Fig. 6D ). Limb I with outer distal lobe bearing single large seta. A long seta, bilaterally armed by short setules distally, near ejector hooks ( Fig. 6G ). Limb VI with inner margin lined by continuous row of long, fine setules.

Size in our sample 0.53–0.64 mm (n=2).

Ephippial female, male. Unknown.

Differential diagnosis. See Kotov and Štifter (2006).

Possible differences from Mexican populations. I. nevadensis is described from Lake La Luna in the crater of the volcano Nevado de Toluca, State of Mexico, Mexico, (19°06'13''N, 99° 45'20''W, 4680 m.a.s.l.) (Holotype: female, USNM 243648 . Paratypes: 2 females, USNM 243649 ; 1 female, UNAM CL-1072; 2 females, ECO-CH-ZOO 460) .

Our two females had (1) somewhat longer lateral setae on postabdomen (approximately as long as paired spines, sometimes even longer); (2) finer denticles on sides of postabdomen basally; (3) smaller denticles on antenna I.

Unfortunately, two specimens are not enough to speak about a consistence of such differences. In addition, Mexican populations need to be restudied for accurate comparison with other localities, because some fine details were not adequately described by Cervantes-Martínez et al. (2000), see Kotov and Elías-Gutiérrez (2009).

Distribution. Previously found only in two adjacent lakes, La Luna and El Sol, in the crater of the volcano Nevada de Toluca, Mexico. Now we added a very distant locality, also in high mountains. The distributional area seems to be disrupted, or the Chilean population may belong to a separate taxon.

Figures

FIGURE 5. Ilyocryptus cf. nevadensis, adult parthenogenetic female from a small stream in wet prairie, Parinacota Region, Chile. A. Lateral view; B. Anterior view; C–E. Head, lateral, ventral and dorsal view; F. Reticulation on valve; G–I. Setae at antero-ventral, ventral and posterior margin of valve; J–K. Postabdomen and armature of its basal portion; L. Large lateral setae; M. Postabdominal claw; N. Postabdominal seta. Scale bars 0.1 mm.

FIGURE 6. Ilyocryptus cf. nevadensis, appendages of adult parthenogenetic female from a small stream in wet prairie, Parinacota Region, Chile. A–B. Antenna I, lateral and anterior view; C. Antenna II, anterior view; D. Its exopod. E–F. Apical and lateral swimming seta of antenna II; G. Distal portion of limb I. Scale bars 0.1 mm.