Rhagovelia yela subgroup

The R. yela subgroup is a distinctive set of species occurring in the Louisiade Archipelago to the east of New Guinea proper and contains three species: R. tagula, R. yela and R. bwagabwaga . The most salient character states defining this group are the presence of a transverse fold across the middle portion of the female abdominal connexiva adjacent to tergites III–V (Figs. 202, 221, 228, 235), with the connexival margins immediately anterior to this fold bearing thick, stiff black setae. This fold, which is seen in no other species in the region, allows an upward flexure of the posterior abdomen, which is angled up at 45° in R. tagula when viewed laterally, and is vertically oriented in R. yela . In R. bwagabwaga the thick fringe of dark setae is present on the basal connexiva, but the transverse connexival fold is incipient, with this portion of the connexiva being narrowed and glabrous, and the abdomen is not reflexed. It therefore appears that there is a west to east morphocline running from the least modified abdominal character state in R. bwagabwaga on Misima Island through R. tagula on Tagula Island to the highly modified abdomen in R. yela on Rossel Island.

The male body form and genitalia in the three above species are similar to other members of the R. papuensis group (Figs. 220, 227, 234), except that the male proctiger in R. yela has the basal section broad and roughly parallel-sided, with the basolateral and distolateral lobes weakly developed and confluent (Fig. 225). All the members of this subgroup inhabit rocky upland streams, occurring in riffle tailraces and on flowing pools (Figs. 226, 233, 239).