Moribaetis

Romero, David & Esquivel, Carlos, 2018, Moribaetis brachiostrinus (Ephemeroptera: Baetidae), a new species of mayfly from Costa Rica, Zootaxa 4433 (3), pp. 531-541 : 540

Key to described mature nymph of Moribaetis species (modified from Waltz & McCafferty 1985)

1. Incisors of mandible fused into one blade-like structure lacking denticles; antennae often reaching or surpassing gill 6 or 7; frons with distinct medial pigmented area between ocelli.......................................... M. maculipennis

- Incisors of mandible with easily discernible denticles; antennae reaching gill 1–5; frons without medial pigmented area.... 2

2. Paraglossa with three apical rows of setae; segment II of labial palp with four dorsal setae; maxillary palp not exceeding 3/4 of galea-lacinia length (unpub. data)................................................................ M. macaferti

- Paraglossa with two apical rows of setae; segment II of labial palp with six or more dorsal setae; maxillary palp subequal to galea-lacinia in length.................................................................................. 3

3. Antennae reaching gill 1–2; labrum with 8–9 spines in ventral sublateral row; paraproct with a distinctive triangular projection on posterior margin ( Fig. 7 d )............................................................... M. brachiostrinus

- Antennae reaching gill 3–5; labrum with 10 or more spines in ventral sublateral row (unpub. data); paraproct without triangular projection on posterior margin.................................................................... M. salvini

Figures

FIGURE 7. Moribaetis brachiostrinus sp. nov., mature nymph. a) procoxal osmobranchia detail, b) gill, c) leg, d) paraproct.