Labiobaetis balkei, Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2018

Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2018, The incredible diversity of Labiobaetis Novikova & Kluge in New Guinea revealed by integrative taxonomy (Ephemeroptera, Baetidae), ZooKeys 804, pp. 1-136 : 5-7

1. Labiobaetis balkei sp. n. Figures 2, 3, 58a, 64a

Diagnosis.

Larva. Following combination of characters: A) labrum dorsal submarginal arc of setae composed of 10-11 spatulate, apically pectinate setae; B) labial palp segment II with a large, lobed distomedial protuberance; C) fore femur length ca. 3 × maximum width, dorsally with a row of ca. 17 curved, spine-like setae on margin and a few curved, spine-like setae near proximal margin; D) tibia dorsally with stout, spatulate, apically rounded setae along margin; E) claw with a row of 11-12 denticles; F) paraproct distally expanded.

Description.

Larva (Figs 2, 3, 58a). Body length 5.3 mm.

Colouration. Head, thorax and abdomen dorsally brown, thorax with brighter, faint pattern as in Fig. 58a. Head and thorax with bright median, dorsal suture. Thorax and abdomen ventrally colourless, femur with brown, distomedial spot, dorsal margin of femur brown, legs otherwise colourless, caudal filaments colourless.

Antenna with scape and pedicel sub-cylindrical, without distolateral process at scape; flagellum with lanceolate spines on apex of each segment.

Labrum (Fig. 2a, b). Rectangular, length 0.7 × maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submarginal arc of setae composed of 10-11 long, spatulate, apically pectinate setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid setae; ventral surface with 12 short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 2c, d). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles plus one small intermediate denticle. Inner margin of innermost denticle with a row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola slightly convex, with minute denticles. Tuft of setae at apex of mola present.

Left mandible (Fig. 2e, f). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles. Prostheca robust, apically with small denticles and comb-shape structure. Margin between prostheca and mola straight, with minute denticles towards subtriangular process. Subtriangular process long and slender, above level of area between prostheca and mola. Denticles of mola apically constricted. Tuft of setae at apex of mola present.

Both mandibles with lateral margins almost straight. Basal half with fine, simple setae scattered over dorsal surface.

Hypopharynx (Fig. 2g). Lingua shorter than superlingua. Lingua longer than broad; medial tuft of stout setae present; distal half not expanded. Superlingua rounded; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 2h). Galea-lacinia with two simple, robust apical setae under crown. Inner dorsal row of setae with three denti-setae, distal denti-seta tooth-like, middle and proximal denti-setae slender, bifid and pectinate. Medially with one spine-like seta and five long, simple setae. Maxillary palp 1.2 × as long as length of galea-lacinia; two segmented. Palp segment II 1.8 × length of segment I. Setae on maxillary palp fine and simple, scattered over surface of segments I and II. Apex of last segment rounded, with excavation at inner distolateral margin.

Labium (Fig. 2i). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with seven spine-like setae increasing in length distally; apex with three long, robust, pectinate setae; outer margin with five long, spine-like setae; ventral surface scattered with fine, simple setae. Paraglossa sub-rectangular, curved inward; apex rounded, ventrally with three rows of long, robust, apically pectinate setae; dorsally with a row of four medium, simple setae; ventrally with three long, spine-like setae near inner margin. Labial palp with segment I 0.6 × length of segments II and III combined. Segment I covered with short, fine, simple setae ventrally and micropores dorsally. Segment II with a large, lobed distomedial protuberance; distomedial protuberance 0.9 × width of base at segment III; inner and outer margin both with short, fine, simple setae; dorsally with two long, spine-like, simple setae. Segment III slightly pentagonal; apex slightly pointed; length 1.1 × width; ventrally covered with long and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg (Fig. 3a, b, c). Ratio of foreleg segments 1.1:1.0:0.4:0.2. Femur. Length ca. 3 × maximum width. Dorsal marign with a row of 17-18 curved, spine-like setae and 1-4 curved, spine-like setae near proximal area, length of setae 0.15 × maximum width of femur. Apex rounded with one pair of curved, spine-like setae and many short, stout, apically rounded setae. Many stout, lanceolate setae and a few fine, simple setae scattered along the ventral marign; femoral patch poorly developed. Tibia. Dorsal margin with stout, lanceolate, apically rounded setae and very fine, simple setae scattered. Ventral margin with a row of curved, spine-like setae and some longer, spine-like, bipectinate setae and a tuft of long, fine, simple setae on apex. Anterior surface scattered with many stout, lanceolate setae. Tibio-patellar suture present on basal 1/2. Tarsus. Dorsal margin with a row of fine, simple setae. Ventral marign with a row of curved, spine-like setae. Tarsal claw with one row of 11-12 denticles; distally pointed; with four stripes; subapical setae absent.

Tergum (Fig. 3d). Surface with irregular rows of slightly W-shaped scale bases and scattered fine, simple setae and micropores; scales short, apically rounded. Posterior margin of tergum IV with triangular spines, wider than long.

Gills (Fig. 3e). Present on segments II–VII. Margin with small denticles intercalating fine simple setae. Tracheae extending from main trunk to inner and outer margins. Gill IV as long as length of segments V and 2/3 VI combined. Gill VII as long as length of segments VIII and 1/2 IX combined.

Paraproct (Fig. 3f). Distally expanded, with many marginal, stout spines. Surface with U-shaped scale bases and scattered fine, simple setae and micropores. Postero-lateral extension (cercotractor) with small marginal spines.

Etymology.

Dedicated to Michael Balke (Zoologische Staatssammlung München, ZSM), who collected most of the fantastic material treated in this study.

Distribution.

New Guinea.

Biological aspects.

The specimens were collected at an altitude of 1400 m a.s.l.

Type-material.

Holotype. Nymph (on slide, GBIFCH 00465156), Papua New Guinea, Central, Kokoda Trek, 1400 m, Jan 2008, 09°01.95'S, 147°44.46'E, Posman (PNG 172). Deposited in ZSM. Paratypes. 37 nymphs (2 on slides, GBIFCH 00465157, GBIFCH 00465158, 20 in alcohol, GBIFCH 00515225, deposited in MZL; 15 in alcohol, GBIFCH 00515226, deposited in ZSM), same data as holotype.