Labiobaetis vallus, 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 : 103-107

31. Labiobaetis vallus sp. n. Figures 56, 57, 63d, 64b

Diagnosis.

Larva. Following combination of characters: A) labrum dorsal submarginal arc of setae composed of 23 long, lanceolate, apically pointed setae; B) maxillary palp with segment II 2.4 × longer than length of segment I, slender, apically pointed, without excavation at inner lateral margin; C) labial palp segment III sub-rectangular, apically slightly pointed; D) labial palp segment II with an elongated, thumb-like distomedial protuberance; E) fore femur slender, length ca. 4 × maximum width, dorsal margin with a row of ca. 10 curved, spine-like setae and some stout, pointed setae near margin.

Description.

Larva (Figs 56, 57, 63d). Body length 5.4 mm.

Colouration. Thorax and abdomen dorsally brown, with bright pattern as in Fig. 63d. Thorax with bright median, dorsal line. Thorax and abdomen ventrally colourless, abdomen light brown toward the end. Legs colourless, femur with proxomedial and distomedial brown spots, tibia with proximal and distal brown spots. Caudal filaments light brown.

Antenna with scape and pedicel sub-cylindrical, without distolateral process at scape.

Labrum (Fig. 56a, b). Rectangular, length 0.6 × 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 23 long, lanceolate setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with five short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 56c, d). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles. Inner margin of innermost denticle with a row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola slightly convex. Tuft of setae at apex of mola present.

Left mandible (Fig. 56 e–g). Incisors fused. Outer and inner sets of denticles with 3 + 4 denticles and one minute intermediate denticle. 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. 56h). Lingua longer than superlingua. Lingua about as broad as long; medial tuft of stout setae present; distal half not expanded. Superlingua rounded; lateral margin angulate; fine, long, simple setae along distal margin.

Maxilla (Fig. 56i). 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 bipectinate, spine-like seta and five long, simple setae. Maxillary palp 1.2 × as long as length of galea-lacinia; two segmented. Palp segment II 2.4 × length of segment I. Setae on maxillary palp fine and simple, scattered over surface of segments I and II. Apex of last segment slightly pointed, without excavation at inner distolateral margin.

Labium (Fig. 56j). 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 six long spine-like setae increasing in length distally; ventral surface with fine, simple setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, apically pectinate setae; dorsally with five medium, simple setae; ventrally with four long, spine-like setae near inner margin. Labial palp with segment I 0.7 × length of segments II and III combined. Segment I covered with short and medium, fine, simple setae ventrally and with micropores dorsally. Segment II with an elongated, thumb-like distomedial protuberance; distomedial protuberance 0.5 × width of base of segment III; inner and outer margin both with short, fine, simple setae; dorsally with row of six medium, spine-like, simple setae. Segment III sub-rectangular; apex slightly pointed; length 1.0 × width; ventrally covered with long and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg (Fig. 57 a–d). Ratio of foreleg segments 1.4:1.0:0.6:0.2. Femur. Length ca. 4 × maximum width. Dorsal margin with a row of ca. 10 curved, spine-like setae and some stout, pointed setae near margin; length of setae 0.2 × maximum width of femur. Apex rounded; with one pair of curved, spine-like setae and some minute setae. Stout, lanceolate, bipectinate setae along ventral margin; femoral patch absent. Tibia. Dorsal margin with a row of curved, spine-like setae and long, fine, simple setae. Ventral margin with a row of curved, spine-like setae, apically longer, dense and bipectinate and with a tuft of long, fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Tibio-patellar suture present on basal 1/2. Tarsus. Dorsal margin with a row of short, spine-like setae and long, simple setae. Ventral margin with a row of curved, spine-like, bipectinate setae. Tarsal claw with one row of 11-13 denticles; distally pointed; with two stripes; subapical setae absent.

Tergum (Fig. 57e). Surface with irregular rows of shallow U-shaped scale bases and scattered micropores. Posterior margin of tergum IV with triangular spines, longer than wide.

Gills (Fig. 57f). 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 unknown, gill III as long as segments IV and 1/2 V combined. Gill VII unknown.

Paraproct (Fig. 57g). Distally not expanded, with ca. 21 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.

Refers to the remarkable, fence-like, dorsal, submarginal arc of setae of the labrum.

Distribution.

New Guinea.

Biological aspects.

The specimen was collected at an altitude of 400 m a.s.l.

Type-material.

Holotype. Nymph (on slide, GBIFCH 00465226), Papua New Guinea, Madang, Keki, Adalbert Mts, 400 m, 29 Nov 2006, 04°43.06'S, 145°24.44'E, Binatang Boys (PNG 119). Deposited in ZSM.