10. Labiobaetis kokoda sp. nov.

Figs 32, 33, 34, 35, 36, 37, 38

Diagnosis.

Larva. Following combination of characters differentiates L. kokoda sp. nov. from other species of Labiobaetis: A) labrum length 0.7 × maximal width; dorsal submarginal arc of setae consisting of one plus 3-5 simple setae, 1st and 2nd setae after submedian seta closely together (Fig. 33a-c); B) incisor and kinetodontium of right mandible with four and three denticles; margin between prostheca and mola slightly convex, smooth (Fig. 33d, e); C) incisor and kinetodontium of left mandible with three and three denticles; margin between prostheca and mola almost straight, smooth (Fig. 33f, g); D) hypopharynx with well-developed medial tuft of stout setae (Fig. 34a); E) maxillary palp longer than galea-lacinia; segment II without distolateral excavation, apically pointed, constricted (Fig. 34b, c); F) labial palp segment II with thumb-like, distomedial protuberance; segment III oblong (Fig. 35a, d); G) femur dorsally with row of ca. 12 long, spine-like setae on margin; several such setae additionally in partial 2nd row near margin (Fig. 36a, b); H) claw with ca. 14 denticles (Fig. 36i); I) posterior margin of abdominal tergum IV with triangular or rounded spines, wider than long (Fig. 37c); J) antennal scape without distolateral process (Fig. 37a).

Description.

Larva (Figs 32 - 37). Body length ca. 3 mm (immature). Cerci: broken. Paracercus ca. 0.4 × body length. Antenna ca. 2.5 × head length.

Cuticular colouration (Fig. 32a, b). Antenna light brown, darker at distal margins of segments. Head, thorax and abdomen dorsally brown, with pattern as in Fig. 32a; abdominal terga I, V and IX-X brighter. Head, thorax and abdomen ventrally light brown; abdominal sterna VI-VIII darker, IX-X brighter. Legs light brown, darker along dorsal margins of tibia and tarsus, femur medially and apically darker. Caudalii light brown.

Antenna (Fig. 37a) with scape and pedicel sub-cylindrical, without distolateral process at scape. Pedicel distally with triangular scales.

Labrum (Fig. 33a-c). Sub-rectangular, length 0.7 × maximum width. Distal margin with deep medial emargination and small process. Dorsally with medium, fine, simple setae scattered over surface; submarginal arc of setae composed of 3-5 long, simple setae, 1st and 2nd seta after submedian seta closely together. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid setae.

Right mandible (Fig. 33d, e). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with three denticles, inner margin of innermost denticle with row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola slightly convex, smooth. Tuft of setae at apex of mola present.

Left mandible (Fig. 33f, g). Incisor and kinetodontium fused. Incisor with three denticles; kinetodontium with three denticles. Prostheca robust, apicolaterally with small denticles and comb-shaped structure. Margin between prostheca and mola almost straight, smooth. Subtriangular process above level of area between prostheca and mola. Tuft of setae at apex of mola present.

Both mandibles with lateral margins almost straight.

Hypopharynx and superlinguae (Fig. 34a). Lingua slightly longer than superlinguae. Lingua longer than broad; medial tuft of stout setae well developed, distolaterally with two additional tufts of setae; distal half laterally slightly expanded. Superlinguae distolaterally slightly protruding; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 34b-d). Galea-lacinia ventrally with two simple, apical setae below canines. 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 feathered spine-like seta and ca. six long, simple setae. Maxillary palp ca. 1.1 × length of galea-lacinia; 2-segmented; palp segment II subequal in length to segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment without distolateral excavation, apically slightly pointed, constricted.

Labium (Fig. 35a-e). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ca. six spine-like seta; apex with two long and one medium robust, apically pectinate setae; outer margin with ca. six spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa sub-rectangular, slightly curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area; ventrally ca. four medium, fine, simple setae in anteromedial area; dorsally with five long, spine-like setae near inner margin. Labial palp with segment I approx. as long as length of segments II and III combined. Segment II with thumb-like, distomedial protuberance; distomedial protuberance 0.4 × width of base of segment III; ventral surface with short, fine, simple setae; dorsally with row of ca. four spine-like setae near outer margin. Segment III oblong; length ca. 1.1 × width; ventrally covered with short to medium, spine-like, simple setae and short, fine, simple setae. Mentum ventrally with medium fine, simple setae scattered on distal part of surface.

Hind protoptera absent.

Legs (Fig. 36a-j). Ratio of foreleg segments 1.5:1.0:0.8:0.3. Femur. Femur very wide, length ca. 2.3 × maximum width. Dorsal margin with row of ca. 12 long, curved, spine-like setae, and some additional spine-like setae in partial 2nd row near margin; length of setae 0.2 × maximum width of femur. Apex rounded, with a pair of long, spine-like setae and several medium, spine-like setae. Apex on posterior side with few short, stout, setae on fore and middle leg, absent on hind leg. Stout, lanceolate, pointed setae scattered along ventral margin; several of such setae on distomedial surface. Femoral patch rudimentary on fore and middle legs, reduced on hind leg. Tibia. Dorsal margin with row of short, spine-like, pointed setae. Ventral margin with row of short, curved, spine-like setae, on apex a tuft of fine, simple setae. Anterior surface with short, stout, lanceolate, pointed setae along patellatibial suture. Posterior surface without stout setae. Patellatibial suture present on basal 2/3 area. Tarsus. Dorsal margin with few short, stout setae. Ventral margin with row of curved, spine-like setae increasing in length distally. Claw with one row of ca. 14 denticles; distally pointed; without subapical seta on.

Abdominal terga (Fig. 37c). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I smooth, without spines; II with rounded spines, much wider than long; III-VI with triangular or rounded spines, wider than long; VII-IX with triangular spines, longer than wide.

Abdominal sterna. Posterior margin of sterna: I-VI smooth, without spines; VII-IX with small, triangular spines.

Tergalii (Fig. 37d-f). Present on segments II-VII. Margin with small denticles intercalating fine, simple setae. Anal margin with both short and long, fine setae. Costal margin with alternating larger and smaller denticles. Tracheae not reaching inner and outer margins. Tergalius IV as long as length of segments V and VI combined.

Paraproct (Fig. 31f). Distally slightly expanded, with ca. 22 stout, marginal spines. Surface scattered with U-shaped scale bases. Cercotractor with numerous small, marginal spines.

Etymology.

Referring to the Kokoda Trek in Central Prov. of Papua New Guinea, along which the specimens were collected.

Distribution.

Papua New Guinea, Central Prov. (Fig. 38a).

Biological aspects.

The specimens were collected at an altitude of 1390 m, together with Labiobaetis lobatus Kaltenbach & Gattolliat, 2018 and other species of Labiobaetis .

Type material.

Holotype. PAPUA NEW GUINEA • larva; Central Prov., Kokoda Trek; 09°00'20"S, 147°44'15"E; 1390 m; i.2008; leg. Posman; (PNG 173); on slide; GBIFCH00975629; ZSM. Paratypes. PAPUA NEW GUINEA • 2 larvae; same data as holotype; on slides; GBIFCH00592683, GBIFCH00592684; MZL.