Procerobaetis Kaltenbach & Garces & Gattolliat 2020, gen. nov.

Procerobaetis Kaltenbach & Gattolliat gen. nov. urn:lsid:zoobank.org:act: AF35EE1B-253D-4A27-8B46-AB1BED25D1F9 Figs 1–3, 6M, 7A, 12–14 Type species Procerobaetis leptobranchius gen. et sp. nov., by present designation. Diagnosis Larva This new genus is distinguished by the combination of the following characters: A) body elongate and slender, abdomen dorsoventrally flattened, head and thorax in lateral view rounded, head clearly hypognathous (Figs 12–13); B) base of antennae close to each other, with carina between them (Fig. 6M); C) antenna without process on scape, with spines on apex of flagellum segments, maximally expressed on flagellum segment IX (Fig. 3A); D) labrum on dorsal surface with many long, stout, simple setae, erratically distributed, not arranged in one arc (Fig. 1A); E) right mandible with a row of thin setae at inner margin of innermost denticle, a simple stick-like, apicolaterally pectinate prostheca and a row of long, stout setae between prostheca and mola (Fig. 1 B–C); F) left mandible with a row of short, stout setae and minute denticles between prostheca and mola, both directed toward subtriangular process, no setae at apex of mola (Fig. 1D); G) hypopharynx with a medial tuft of stout setae (Fig. 1F); H) 3-segmented maxillary palp much longer than galea-lacinia (Fig. 1G); I) glossae basally broad, narrowing toward apex, slightly shorter than paraglossae, ventral surface covered with erraticly distributed setae, paraglossae sub-rectangular, apically curved, labial palp segment II with small distolateral expansion, segment III sub-quadrangular (Fig. 1H); J) legs with short, laterally pectinate setae ventrally on femur, tibia and tarsus, femoral patch absent on all legs, patellotibial suture present on all legs, claw elongate and slender, pointed, slightly curved, with one row of many denticles increasing in length toward apex (Fig. 2 A–F); K) gills elongate, distally noticeably pointed, at least gills I and II with very long, extended apex (Figs 3 B–H, 10B–H); L) posterior margins of tergites I–VII without spines (Fig. 2G); M) paraproct without prolongation at posterior margin (Fig. 2H). Imagines Unknown. Etymology Procerobaetis is a combination of Procero – in reference to the elongate, slender habitus of the larvae – and baetis to highlight its superficial similarities with the genus Baetis Leach, 1815 s. lat. The gender is masculine. Description: larva Body Elongate and slender, abdomen dorsoventrally flattened, head and thorax in lateral view rounded, head hypognathous (Figs 12–13). Head ANTENNA (Figs 3A, 6M, 7A, 10A). Long, ca. 2× as long as head length; scape without process; scape and pedicel almost bare; flagellum with lanceolate spines at apex of each segment, longer at inner lateramargin, increasing in length distally until segment IX to XI and decreasing thereafter. Bases of antennae close to each other, with carina between them. LABRUM (Fig. 1A). Rectangular, wider than long; dorsal surface with many long, stout, simple setae, erratically distributed and not arranged in an arc; distolateral margin with feathered setae, distomedial margin with bifid setae. RIGHT MANDIBLE (Fig.1 B–C). Canine with largely fused incisors with well developed, apically rounded denticles, inner margin of innermost denticle with a row of thin setae; prostheca stick-like, apicolaterally pectinate; margin between prostheca and mola with a row of long, stout setae. LEFT MANDIBLE (Fig. 1 D–E). Canine with largely fused incisors with well developed, apically rounded denticles; prostheca robust, apically with small denticles and comb-shape structure; margin between prostheca and mola with a row of short stout setae and minute denticles, both directed toward subtriangular process; no setae at apex of mola. HYPOPHARYNX (Fig. 1F). With a medial tuft of stout setae. MAXILLA (Fig. 1G). Apically with three stout teeth and three denti-setae, distal denti-seta tooth-like, other denti-setae slender, bifid and pectinate; maxillary palp with three segments, much longer than galea-lacinia. LABIUM (Fig. 1H). Glossae basally broad, narrowing toward apex, slightly shorter than paraglossae, ventral surface covered with erratically distributed setae; paraglossae sub-rectangular, apically curved inward, apical margin with three rows of long setae; labial palp 3-segmented, segment II with small distolateral expansion, segment III sub-quadrangular. Mentum with scattered fine, simple setae at least in distal area. Thorax HINDWING PADS (Fig. 2I). Absent. FORELEG (Fig. 2 A–F). Long and slender; dorsal margin of femur with a row of medium, spine-like setae and many stout, lanceolate, laterally pectinate setae scattered along ventral margin, femoral patch absent; dorsal margin of tibia bare or with a row of fine setae, ventral margin with a row of stout, lanceolate, laterally pectinate setae; tarsus dorsally bare or with a row of fine setae, ventral margin with a row of stout, lanceolate, laterally pectinate setae; tarsal claw elongate and slender, pointed, slightly curved, with one row of many denticles increasing in length toward apex, subapical setae absent. Abdomen TERGITES (Fig. 2G). Posterior margin of segments I–VII smooth, without spines. GILLS (Figs 3 B–H, 10B–H). Seven pairs of single gills on segments I–VII, dorsally oriented, elongate, slender, distally noticeably pointed, at least gills I and II with very long, extended apex. PARAPROCT (Fig. 2H). With stout marginal spines and without prolongation at posterior margin. CAUDAL FILAMENTS (Fig. 13A). Inner margin of cerci with very thin, long setae; median caudal filament slightly shorter than cerci, bilaterally with very thin, long setae. Description: imagines Unknown. Distribution (Fig. 14) Indonesia: Sumatra; Philippines:Luzon, Mindoro; Thailand (based on a photo provided by B. Boonsoong, pers. comm.). The Baetidae of Southeast Asia are still poorly known, and many locations have not yet been sampled at all. We expect a wider distribution and more species of this genus in Southeast Asia.Published as part of Kaltenbach, Thomas, Garces, Jhoana M. & Gattolliat, Jean-Luc, 2020, A new genus of Baetidae (Insecta, Ephemeroptera) from Southeast Asia, pp. 1-32 in European Journal of Taxonomy 612 on pages 4-6, DOI: 10.5852/ejt.2020.612, http://zenodo.org/record/370217