Compsoneuriella Ulmer, 1939 stat. prop.

Compsoneuriella Ulmer 1939, Arch Hydrobiol. Suppl. 16: p. 563 (adults), p. 672 (nymphs pro parte)

Compsoneuria Braasch & Soldán 1986 Reichenbachia 24: p. 59 et auct seq.

Diagnosis. Imago. Overall number of crossveins in the forewing reduced in number compared to other Heptageniidae, except other members of the tribe Compsoneuriini ( Compsoneuria and Notonurus). Cross veins in the costal and subcostal fields, sometimes also in the radial and median fields, trimmed with violet or brown. Costal and subcostal fields with numerous crossveins (> 15), no rows of crossveins visible in the radial-median fields, sometimes present at apex of the radial field (Fig. 25). Male foreleg with first tarsal segment slightly shorter than the second one (Figs 26–27). Styliger plate faintly convex (Fig. 28). Last segment of the gonopods generally smaller than the previous one. Male genitalia with median titillators, penis lobes with apical, subapical and basal spines (Fig. 29). Lateral sclerite narrow, and basal sclerite well-developed.

Nymph. Head not thickened, dark with whitish spots near the anterior margin (Figs 81–82). Distal dentisetae on maxillae with inner and outer one simple (Figs 48–51). Labial glossae conical with concave outer margin apically (Figs 35, 68, 72, 75). Scattered setae on the maxillae generally fimbriate (Figs 52–53). Supracoxal spurs well developed, sharply acute and often pointed (Figs 81–82). Spines on the upper face of femora pointed, or at least with strongly convergent margins (Figs 37, 66, 69). Inner margin of femora with long and thin setae (Figs 36, 65). Gills generally whitish with well visible tracheation (Figs 38–39). All gills with fibrillous and plate like structures, except gill VII only plate-like. Hind tibiae with one row of fine setae on the outer margin (Figs 36, 65). Tarsal claw with 0- 2 subapical teeth. Caudal filaments with whorls of spine like setae on each segment, without long and thin setae.

Eggs. Chorion covered by flat, fibrillose and rounded structures; on each pole, KCT´s around two times the size of the others; micropyle with single margin (Figs 41–42; Boonsoong & Braasch 2013, fig. 7A–B).

Species included:

Compsoneuriella thienemanni Ulmer, 1939 (imagos, nymphs): Sumatra, Java

Compsoneuriella sp. 1 (imagos, nymphs): Vietnam, Thailand

Compsoneuriella langensis (Braasch & Boonsoong, 2010) (imagos, nymphs): Thailand comb. nov.

Compsoneuriella tagbanua (Braasch & Freitag, 2008) (imagos, nymphs): Philippines (Palawan) comb. nov.

Discussion. As already mentioned, the genus Compsoneuriella corresponds to the concept of Compsoneuria by Braasch & Soldán (1986b) and subsequent authors.

At the nymphal stage, Compsoneuriella is distinguished from its relatives by the contrasted color pattern of the cephalic capsule, with at least 4 whitish dots close to the anterior margin, the acute supracoxal spurs, the presence of long and thin setae on the inner margin of the femora, the bristles on the upper face of femora pointed or at least with margins clearly convergent, the outer distal dentiseta of the maxillae entire, and by the presence of a single row of setae on the hind tibiae.

At the imaginal stage, the combination of the number of forewing crossveins in the costal and subcostal fields, the male foretarsi proportions and genitalia will distinguish the genus from Compsoneuria, but differences with Notonurus were not found.

The eggs of Compsoneuriella differ from those of Compsoneuria by the arrangement of the chorion and the margin of the micropyle. To our knowledge, no eggs of Notonurus are presently described.

Within the tribe Compsoneuriini, Compsoneuriella share several features with the Afrotropical genus Notonurus in the nymphal stage, including the overall color pattern of the head and the pointed supracoxal spurs. Compsoneuriella, however, typically has fimbriate scattered setae of the maxillae together with entire distal dentisetae (Figs. 48–53) whereas those of Notonurus have simple scattered setae on the maxillae and numerous distal dentisetae (Figs 55–58).