Hydromastodon Polegatto & Batista, 2007

Salles, Frederico F., Dominguez, Eduardo, Mariano, Rodolfo & Paresque, Roberta, 2016, The imagos of some enigmatic members of the Hermanella complex (Ephemeroptera, Leptophlebiidae), ZooKeys 625, pp. 45-66 : 48-50

Taxon classification Animalia Ephemeroptera Leptophlebiidae

Hydromastodon Polegatto & Batista, 2007 Figures 3, 4, 7

Diagnosis.

The male imago of Hydromastodon can be distinguished from the other genera of the Hermanella complex by the following combination of characters: 1) Eyes meeting on meson of head (Fig. 3a); 2) Cross vein above fork of MA slanted (Fig. 4a); 3) Fork of MA asymmetrical and fork of MP slightly asymmetrical (MP2 connected to MP1 by a crossvein); 4) Styliger plate with a strong dorsally curved median projection (Fig. 4d, e); 5) Penis divided, each lobe with a long spine ventromedially directed (Fig. 4d, e).

Description of male imago

(in alcohol). Head (Fig. 3a, b): Eyes meeting on meson of head, lower portion of eyes slightly < ½ length of upper portion.

Thorax: Prosternum with rather wide, X-shaped median carina, with similar anterior and posterior arms; similar to Needhamella , as shown by Domínguez and Flowers (1989: fig. 18).

Wings (Fig. 4a, b, c): Maximum width of fore wings 1/3 their maximum length; maximum width of hind wings about ½ their maximum length; maximum length of hind wings 1/6 maximum length of fore wings. Fore wings (Fig. 4a): vein Rs forked slightly> 1/4 distance from base of vein to margin, fork of vein MA asymmetrical and forked at ½ distance from base of vein to margin, cross vein above fork of MA slanted; fork of vein MP slightly asymmetrical and forked 1/3 distance from base of vein to margin; vein ICu1 attached at base to vein CuA by crossvein; vein ICu2 free basally. Hind wings (Fig. 4b, c): costal projection well-developed, acute and located ½ distance from base to apex; vein MP unforked; apex of wings rounded; vein Sc ½ distance from base to wing margin, ending in crossvein; 5 cross veins present.

Legs. Ratio of segments of male forelegs, 0.6:1.0 (0.62 mm): 0.03:0.31:0.28:0.15: 0.08. Claws on each leg dissimilar, with one apically hooked and one blunt, pad-like.

Abdomen: Genitalia (Fig. 4d, e) with segment II of forceps subequal to segment III; segment II of forceps 1/5 length of segment I; styliger plate with strong, dorsally curved, median projection. Penis divided, each lobe with long spine ventromedially directed. Caudal filaments broken off and lost.