Hydromastodon Polegatto and Batista, 2007

Polegatto, C. M. & Batista, J. D., 2007, Hydromastodon sallesi, new genus and new species of Atalophlebiinae (Insecta: Ephemeroptera: Leptophlebiidae) from West and North of Brazil, and notes on systematics of Hermanella group, Zootaxa 1619 (1), pp. 53-60 : 54-55

Hydromastodon Polegatto and Batista , new genus ( Figs. 1 –21)

Type-species: Hydrosmilodon mikei Thomas & Boutonnet 2004, p.72

Mature Nymph, Male ( Fig. 1 ). Head (Fig. 2). Antennae 1.6 to 2.5 length of head.

Labrum ( Fig. 13 ): expanded laterally, length 1/3 of width, and width subequal to that of head capsule; dorsal surface with 12–15 long setae on each side of median line; ventral surface with long setae in an oblique row and short setae on posteromedian area; anterior and posterolateral margin with short setae, some of those relatively long. Mandibles (Figs. 19-21): incisors and molae as in other genera of Hermanella group in general shape; prosthecae with numerous long and fine setae; both mandibles with V’ shaped ventral row of setae. Maxillae: (Figs. 16-17) with a large tooth on anteromedian angle, as long as width of the apex of galealaciniae; anteromedian margin of galeolaciniae strongly sinuous; apex of galeolaciniae wider than base; a weak posterolateral prominent area on the galealaciniae; setae on crown of galeolaciniae numerous; maxillary palpi almost as long as maxillae; first segment of maxillary palpi robust; third segment of maxillary palpi with long and fine setae; apex of third segment bare and soft (Fig. 12). Hypopharynx: as in Fig. 18. Labium (Fig. 14-15). Glossae and paraglossae with setae as in Fig. 10,; labial palpi: first segment subequal in length to segment two, third segment about half of length of segment two.

Thorax. Legs (Figs. 7-10). Femora with long, strong and fine setae on posterior margin, and short setae on anterior margin; tibiae and tarsi with setae as in Figs. 7-9; the strong setae on femora, sometimes on tibiae, apically clavate (Fig. 10), and scale-like setae can be present on femora; tarsal claws ( Fig. 6 ) with subequal denticles in two separate rows; a large subapical denticle absent.

Abdomen (Figs. 4, 12). Posterolateral spines on segments 6 to 9 or 7 to 9. Gills (Fig. 11) relatively slender and long, width at least 1/5 of length; gills with a fine apical projection; main trachea visible; ninth sternite with two sharp projections, longer in males.

Diagnosis: Hydromastodon can be distinguished from other genera of Hermanella group by the combination of: tarsal claws without large subapical denticle and subequal denticles in two different rows; abdominal posterolateral spines on seg. 6 or 7 to 9; and clavate setae on legs.

Adults: unknown

Etymology: in the genus Hydrosmilodon , described by Flowers & Dominguez (1991), the name refers to sabertooth-tiger, because of the big maxillary tusks; however, species of the Hermanella group are herbivo- rous, i.e. filterers; therefore, mastodon, meaning an extinct elephant, which could use tusks against vegetation; hydro, meaning water.

Distribution: State of Mato Grosso, West of Brazil, to State of Roraima, North of Brazil, possibly in other states of West and North region, and also in French Guiane (Thomas et al. 2004).

Figures

FIGURES 1 TO 5. Hydromastodon sallesi: 1, nymph of male. 2, male head. 3, female head. 4, male abdomen, dorsal view. 5, female abdomen, dorsal view.

FIGURES 6 TO 12. Hydromastodon sallesi: 6, tarsal claws. 7, leg I, right, dorsal view. 8, leg II, right, dorsal view. 9, leg III, left, dorsal view. 10, detail of clavate setae on femur I. 11, gill 4. 12, male abdomen, ventral view.

FIGURES 13 TO 21. Hydromastodon sallesi: 13, labrum, left: ventral view, right: dorsal view. 14, labium, left: dorsal view, right: ventral view. 15, labial palp, detail of third segment. 16, maxilla, right, dorsal view. 17, maxillary palp, third segment, right, dorsal view. 18, Hypopharynx, ventral view. 19, mandible, right, ventral view. 20, detail of incisors, prostheca and mola of right mandible, ventral view. 21, same of left mandible, ventral view.