Larva. Following combination of characters: A) dorsal surface of labrum with submedian seta and two long, simple setae in submarginal position (Fig. 2b); B) right mandible: incisor with four denticles, kinetodontium with four denticles (Fig. 2c); C) left mandible: incisor with four or five denticles, kinetodontium with three denticles; margin between prostheca and mola with row of minute denticles (Fig. 2d); D) fore femur length ca. 3× maximum width, dorsal margin with 7–11 curved, spine-like setae (Fig. 5a); E) claw with 11 or 12 denticles (Fig. 5b); F) hind protoptera minute (Fig. 5d); G) tergalii on abdominal segments I–VII; H) paraproct with ca. six stout, large marginal spines (Fig. 6b); I) posterior margins of abdominal terga: I–III smooth, without spines; IV–V with rudimentary spines or smooth; VI–IX with triangular, sharply pointed spines (Fig. 6a).

Larva (Figs 1–7). Body length 3.3–4.9 mm. Cerci: ca.½ of body length. Paracercus: ca. ⅔ of cerci length. Antennae broken.

Colouration (Fig. 1a–c). Head, thorax, and abdomen dorsally brown; abdominal terga VI and VII darker, abdominal terga VIII–X pale brown, except apex of tergum X brown. Head ventrally brown, thorax and abdomen ventrally pale brown, abdominal sterna VII and VIII darker. Legs pale brown, femur basomedially and distomedially with uncoloured areas. Caudalii brown.

Labrum (Fig. 2a, b). Slightly conical, length 0.76× maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submedian seta and two long, simple, submarginal setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid, pectinate setae.

Right mandible (Fig. 2c). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with four denticles, inner margin of innermost denticle with row of thin setae. Prostheca stick-like, apicolaterally denticulate. Margin between prostheca and mola straight, with row of setae-like processes. Tuft of setae at apex of mola present.

Left mandible (Fig. 2d). Incisor and kinetodontium fused. Incisor with four or five denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with row of minute denticles. Tuft of setae at apex of mola absent.

Hypopharynx and superlinguae (Fig. 3a). Lingua approx. as long as superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed, broad; distal half laterally not expanded. Superlinguae distally straight; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 3b–d). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like seta and ca. four long, simple setae. Maxillary palp 1.3× as long as length of galea-lacinia; 2-segmented; palp segment II approx. as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment pointed.

Labium (Fig. 4a–c). Glossa basally broad, narrowing toward apex; nearly as long as paraglossa; inner margin with ca. ten spine-like setae; apex with two long and one medium, robust setae; outer margin with ca. six spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and two medium, simple setae in inner anterolateral area; dorsally with row of three long, spine-like, simple setae near inner margin. Labial palp with segment I 1.2× length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without protuberance; ventral surface with short, fine, simple setae; dorsally with row of four long, spine-like setae. Segment III sub-quadrangular; inner apical margin slightly concave, with some setae-like processes; apex with rounded protrusion; length subequal to width; ventrally with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 5e) minute.

Foreleg (Fig. 5a–c). Ratio of foreleg segments 1.5:1.0:0.8:0.3. Femur. Length ca. 3× maximum width. Dorsal margin with 7–11 curved, spine-like setae; length of setae 0.21× maximum width of femur. Apex rounded, with pair of spine-like setae. Stout, lanceolate setae scattered along ventral margin; femoral patch absent. Tibia. Dorsal margin with 0–3 short, spine-like setae, and with row of fine, simple setae; on apex one stout, apically rounded seta. Ventral margin with row of short, curved, spine-like setae, on apex some longer, spine-like, pectinate setae. Anterior surface with row of stout, lanceolate setae near ventral margin. Patellatibial suture present on basal half. Tarsus. Dorsal margin with row of fine, simple setae. Ventral margin with row of curved, spine-like setae. Claw with one row of 11 or 12 denticles; distally pointed; subapical setae absent.

Middle and hind legs. As foreleg, but tibiae at dorsal margin with 4–6 spine-like setae.

Abdominal terga (Fig. 6a). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I–III smooth, without spines; IV and V with rudimentary spines or smooth; VI–IX with triangular, sharply pointed spines.

Abdominal sterna. Posterior margins smooth, without spines.

Tergalii (Fig. 5d). Present on segments I–VII. Margin with small denticles intercalating fine simple setae. Tracheae extending from main trunk to inner and outer margins. Tergalius I ca. ½ length of segment II; Tergalius IV as long as length of segments V and ½ VI combined; Tergalius VII as long as length of segments VIII and ½ IX combined.

Paraproct (Fig. 6b). With 6–9 stout, marginal spines. Surface scattered with U-shaped scale bases. Cercotractor with numerous small, marginal spines.

Subimaginal gonostyli (Fig. 6c) developing under cuticle of male last instar larvae folded in Nigrobaetis-type (Kluge 2004: fig. 29G).

Adult stages. Unknown.

Eggs (Fig. 7a, b). Ovoid; surface cone-like with numerous papillae-like structural elements (polygonal to rounded structure, centrally with a smaller, rounded, slightly elevated area surrounded by a round trench).

Plures in Latin meaning several, referring to the distribution of the species across several islands.

(Fig. 8). Philippines: Leyte, Mindanao, Camiguin.

The specimens were collected on altitudes of 30–660 m, mostly on bottom gravel in run or riffle, partly together with Labiobaetis camiguinensis Kaltenbach, Garces & Gattolliat, 2020 (Camiguin) or L. delocadoi Kaltenbach, Garces & Gattolliat, 2020 (Leyte).

Holotype. Philippines • larva; Leyte, Southern Leyte, Brgy. Malico, San Francisco, Taglibas River; 10°01'07"N, 125°12'35"E; 50 m; 19.-20. X. 2019; leg. Garces and Pelingen; on slide; GBIFCH00592356; PNM. Paratypes. Philippines • 4 larvae; same data as holotype; 3 on slides; GBIFCH00975650; AdMU; GBIFCH00515525, GBIFCH00975682; MZL; 1 in alcohol; GBIFCH00975649; AdMU • 1 larva; Mindanao, Surigao del Sur, Tandag, middle Tandag River; 09°03'33"N, 126°05'57"E; 30 m; 04.XII.2018; leg. Pangantihon; on slide; GBIFCH00592268; MZL • 1 larva; Mindanao, Agusan N, Cabadbaran, Del Pilar, Payas River; 09°11'34"N, 125°36'34"E; 660 m; 23. VI. 2018; leg. Pangantihon; on slide; GBIFCH00975656; AdMU • 2 larvae; Mindanao, Agusan N, Cabadbaran River; 09°10'15"N, 125°40'55"E; 240 m; 03. VI. 2018; leg. H. Freitag and Pangantihon; GBIFCH00975657, GBIFCH00975678; MZL • 6 larvae; Camiguin, Sagay, Bonbon, lower Binangawan River; 30 m, 09°06'39"N, 124°43'45"E; 30 m; 09.XII.2018; leg. H. Freitag; 4 on slides; GBIFCH00654914, GBIFCH00975652; MZL; GBIFCH00592248, GBIFCH00592249; AdMU; 2 in alcohol; GBIFCH00975651, GBIFCH00975653; AdMU.

Larva. Following combination of characters: A) dorsal surface of labrum with submedian seta and two long, simple setae in submarginal position (Fig. 10b); B) right mandible: incisor with four denticles, kinetodontium with four denticles (Fig. 10c); C) left mandible: incisor with four or five denticles, kinetodontium with three denticles; margin between prostheca and mola smooth, without denticles (Fig. 10d); D) fore femur length ca. 3× maximum width, dorsal margin with 8–14 curved, spine-like setae (Fig. 13a); E) claw with 11 or 12 denticles (Fig. 13b); F) hind protoptera absent; G) tergalii on abdominal segments I–VII; H) paraproct with ca. 12 marginal spines (Fig. 14b); I) posterior margins of abdominal terga: I smooth, without spines; II–IX with triangular spines (Fig. 14a).

Larva (Figs 9–14). Body length 2.8–3.9 mm. Caudalii broken. Antennae broken.

Colouration (Fig. 9a, b). Head dorsally pale brown, basolaterally darker; thorax and abdomen dorsally brown; abdominal terga IV and VIII–X pale brown. Head, thorax, and abdomen ventrally pale brown, abdominal sterna VIII–X brighter. Legs pale brown, femur apically brown, with distomedial spot. Caudalii pale brown.

Labrum (Fig. 10a, b). Length 0.7× maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submedian seta and two long, simple, submarginal setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid, pectinate setae.

Right mandible (Fig. 10c). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with four denticles, inner margin of innermost denticle with row of thin setae. Prostheca stick-like, apicolaterally denticulate. Margin between prostheca and mola straight, with row of setae-like processes. Tuft of setae at apex of mola present.

Left mandible (Fig. 10d). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, smooth without denticles. Tuft of setae at apex of mola absent.

Hypopharynx and superlinguae (Fig. 11a). Lingua approx. as long as superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed, broad; distal half laterally not expanded. Superlinguae distally straight; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 11b, c). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like seta and ca. four long, simple setae. Maxillary palp approx. as long as length of galea-lacinia; 2-segmented; palp segment II approx. 1.1× as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment pointed.

Labium (Fig. 12a–d). Glossa basally broad, narrowing toward apex; as long as paraglossa; inner margin with ca. ten spine-like setae; apex with two long and one medium, robust setae; outer margin with ca. four spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and two medium, simple setae in anteromedial area; dorsally with row of three long, spine-like, simple setae near inner margin. Labial palp with segment I 0.9× length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without protuberance; ventral surface with short, fine, simple setae; dorsally with row of three or four long, spine-like setae. Segment III pentagonal; inner apical margin with some setae-like processes; length 1.1× width; ventrally with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera : Absent.

Foreleg (Fig. 13a–d). Ratio of foreleg segments 1.3:1.0:0.8:0.3. Femur. Length ca. 3× maximum width. Dorsal margin with 8–14 curved, spine-like setae; length of setae 0.27× maximum width of femur. Apex rounded, with pair of spine-like setae. Stout, lanceolate setae scattered along ventral margin; femoral patch absent. Tibia. Dorsal margin without or with one short, spine-like seta; on apex one stout, apically rounded seta. Ventral margin with row of short, curved, spine-like setae, on apex two longer, spine-like, pectinate setae. Anterior surface with some stout, lanceolate setae near ventral margin. Patellatibial suture present on basal half area. Tarsus. Dorsal margin almost bare. Ventral margin with row of curved, spine-like setae. Claw with one row of 11 or 12 denticles; distally pointed; subapical setae absent.

Middle and hind legs. As foreleg, but tibia at dorsal margin with 1–4 spine-like setae.

Abdominal terga (Fig. 14a). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I smooth, without spines; II–IX with triangular, pointed spines.

Abdominal sterna. Posterior margins smooth, without spines.

Tergalii (Fig. 13e). Present on segments I–VII. Margin with small denticles intercalating fine simple setae. Tracheae extending from main trunk to inner and outer margins. Tergalius II as long as length of segments III and ½ IV combined; Tergalius VII as long as length of segments VIII and ½ IX combined.

Paraproct (Fig. 14b). With 10–12 stout, marginal spines. Surface scattered with U-shaped scale bases. Cercotractor with numerous small, marginal spines.

Adult stages. Unknown.

Referring to the island of Palawan, where the species was collected.

(Fig. 8). Philippines: Palawan.

The specimens were collected below 100 m in primary and secondary forest, on bottom gravel and on root packs in the run.

Holotype. Philippines • larva; Palawan, San Vincente, waterfall 4km NE Port Barton; 10°23'35"N, 119°09'27"E; 30 m; 18.vi.1997; leg. J. Mendoza; on slide; GBIFCH00975661; PNM. Paratypes. Philippines • 3 larvae; same data as holotype; 3 on slides; GBIFCH00592651; AdMU; GBIFCH0092646, GBIFCH00592647; MZL • 1 larva; Palawan, Roxas, Bgy. Port Barton, mountain river; 10°22'40"N, 119°11'05"E; 90 m; 20.vi.1997; leg. J. Mendoza; in alcohol; GBIFCH00975662; AdMU.

Larva. Following combination of characters: A) dorsal surface of labrum with submedian seta and two long, simple setae in submarginal position (Fig. 16b); B) right mandible: incisor with four denticles, kinetodontium with three denticles (Fig. 16c); C) left mandible: incisor with four denticles, kinetodontium with three denticles; margin between prostheca and mola straight, with four or five long, setae-like processes (Fig. 16d); D) fore femur very slender, length ca. 4.8× maximum width, dorsal margin with eight or nine curved, spine-like setae (Fig. 19a); E) tibia dorsally with row of spine-like setae; F) claw with 14–17 relatively long denticles (Fig. 19c); G) hind protoptera absent; H) tergalii on abdominal segments I–VII; I) paraproct with 10–14 marginal spines (Fig. 20b); J) posterior margins of abdominal terga: I smooth, without spines; II–IX with triangular, pointed spines (Fig. 20a).

Larva (Figs 15–20). Body length 3.7–4.6 mm. Caudalii broken. Antennae broken.

Colouration (Fig. 15a, b). Head, thorax, and abdomen dorsally brown, with lively bright pattern as in Fig. 15a. Noticeable are the bright beige abdominal terga I, IV (with brown marks), and VIII–X. Head, thorax, and abdomen ventrally pale brown, abdominal sterna VIII–X brighter. Legs pale brown, femur darker in distal 2/3. Caudalii bright beige.

Labrum (Fig. 16a, b). Length 0.7× maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submedian seta and two long, simple, submarginal setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae.

Right mandible (Fig. 16c). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with three denticles, inner margin of innermost denticle without row of thin setae. Prostheca stick-like, apicolaterally denticulate. Margin between prostheca and mola straight, with row of setae-like processes. Tuft of setae at apex of mola present.

Left mandible (Fig. 16d). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with four or five long, setae-like processes. Tuft of setae at apex of mola absent.

Hypopharynx and superlinguae (Fig. 17a). Lingua shorter than superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed, broad; distal half laterally not expanded. Superlinguae distally straight; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 17b–d). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like seta and ca. four long, simple setae. Maxillary palp ca. 1.3× as long as length of galea-lacinia; 2-segmented; palp segment II ca. 1.3× as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment pointed.

Labium (Fig. 12a–e). Glossa basally broad, narrowing toward apex; slightly shorter than paraglossa; inner margin with nine or ten spine-like setae; apex with two long and one medium, robust setae; outer margin with ca. eight spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and ca. four medium, simple setae in anteromedial area; dorsally with row of four long, spine-like, simple setae near inner margin. Labial palp with segment I 0.7× length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without protuberance; ventral surface with short, fine, simple setae; dorsally with row of ca. five long, spine-like setae. Segment III slightly pentagonal, inner distal margin slightly concave, with few setae-like processes; length ca. 1.2× maximum width; ventrally with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera : Absent.

Foreleg (Fig. 19a–c). Ratio of foreleg segments 1.3:1.0:0.6:0.2. Femur. Very slender, length ca. 4.8× maximum width. Dorsal margin slightly concave, with eight or nine curved, spine-like setae; length of setae 0.29× maximum width of femur. Apex rounded, with pair of spine-like setae and medium, fine, simple setae. Row of stout, lanceolate setae on ventral margin; femoral patch absent. Tibia. Dorsal margin with row of medium, spine-like setae, on apex one seta somewhat longer and with rounded apex. Ventral margin with row of short to medium curved, spine-like setae, on apex two longer, spine-like, pectinate setae. Anterior surface with stout, lanceolate setae along ventral margin. Patellatibial suture present on basal half. Tarsus. Dorsal margin bare. Ventral margin with row of curved, spine-like setae. Claw with one row of 14–17 relatively long denticles; distally pointed; subapical setae absent.

Middle and hind legs. As foreleg.

Abdominal terga (Fig. 20a). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I smooth, without spines; II–IX with triangular, pointed spines.

Abdominal sterna. Posterior margin of sterna: I–V smooth, without spines; VI with rudimentary spines; VII–IX with triangular spines.

Tergalii (Fig. 19d, e). Present on segments I–VII. Margin with small denticles intercalating fine simple setae. Tracheae extending from main trunk to inner and outer margins. Tergalius I as long as length of segments II and ⅓ III combined; Tergalius IV as long as length of segments V and VI combined; Tergalius VII reaching beginning of segment X.

Paraproct (Fig. 20b). With 10–14 stout, marginal spines. Surface scattered with U-shaped scale bases. Cercotractor with numerous small, marginal spines.

Adult stages. Unknown.

Referring to the island of Sumba, where the species was collected.

(Fig. 40c). Indonesia, Sumba.

The specimens were collected at an altitude of 400 m.

Holotype. Indonesia • larva; Sumba, Waikelo. Stream; 09°35'45"S, 119°20'25"E; 400 m; 27.ix.2011; leg. M. Balke; (SUA04); on slide; GBIFCH00592616; MZB. Paratypes. Indonesia • 2 larvae; same data as holotype; 2 on slides; GBIFCH00592660, GBIFCH00975677; MZL.

Larva. Following combination of characters: A) dorsal surface of labrum with submedian seta and two long, simple setae in submarginal position (Fig. 22b); B) right mandible: incisor with four denticles, kinetodontium with four denticles (Fig. 22c); C) left mandible: incisor with four denticles, kinetodontium with three denticles; margin between prostheca and mola straight, with row of short, setae-like processes (Fig. 22d); D) fore femur length ca. 3× maximum width, dorsal margin with ca. 11 curved, spine-like setae (Fig. 25a); E) tibia dorsally bare, distally with one stout, apically rounded seta (Fig. 25a, d); F) claw with 11 or 12 denticles (Fig. 25c); G) hind protoptera well developed (Fig. 25g); H) tergalii on abdominal segments I–VII; I) paraproct with six or seven marginal spines (Fig. 26b); J) posterior margins of abdominal terga: I–IV(V) smooth, without spines; (V–)VI with rudimentary spines; VII–IX with triangular, pointed spines (Fig. 26a).

Larva (Figs 21–26). Body length 3.6–4.9 mm. Cerci ca. ¾ of body length, paracercus ca. ⅔ of cerci length. Antennae ca. 3× head length.

Colouration (Fig. 21a, b). Head, thorax, and abdomen dorsally brown, abdominal terga VIII and IX bright beige. Head, thorax, and abdomen ventrally pale brown, abdominal sterna VIII–X ecru. Legs pale brown, femur basally, along margins, and in distal area darker. Caudalii pale brown.

Labrum (Fig. 22a, b). Length 0.7× maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submedian seta and two long, simple, submarginal setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae.

Right mandible (Fig. 22c). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with four denticles, inner margin of innermost denticle without row of thin setae. Prostheca stick-like, apicolaterally denticulate. Margin between prostheca and mola straight, with row of setae-like processes. Tuft of setae at apex of mola present.

Left mandible (Fig. 22d). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with row of short, setae-like processes. Tuft of setae at apex of mola absent.

Hypopharynx and superlinguae (Fig. 23a). Lingua approx. as long as superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed, broad; distal half laterally not expanded. Superlinguae distally straight; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 23b–d). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like seta and ca. five long, simple setae. Maxillary palp ca. 1.3× as long as length of galea-lacinia; 2-segmented; segment II bent inwards, distal half sclerotised; palp segment II ca. 1.2× as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment slightly pointed.

Labium (Fig. 24a–f). Glossa basally broad, narrowing toward apex; slightly shorter than paraglossa; inner margin with ca. eight spine-like setae; apex with two long and one medium, robust setae; outer margin with ca. six spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and ca. three medium, simple setae in medial and anteromedial area; dorsally with two long, spine-like, simple setae near inner margin. Labial palp with segment I 0.7× length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without protuberance; ventral surface with short, fine, simple setae; dorsally with row of ca. three long, spine-like setae. Segment III subquadrangular; length ca. 0.9× maximum width; inner apical margin with some setae-like processes (Fig. 24f); ventrally with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 25g) well developed.

Foreleg (Fig. 25a–e). Ratio of foreleg segments 1.4:1.0:0.8:0.3. Femur. Length ca. 3× maximum width. Dorsal margin with ca. 11 curved, spine-like setae; length of setae 0.31× maximum width of femur. Apex rounded, with pair of spine-like setae. Many medium, stout, lanceolate setae along ventral margin; femoral patch absent. Tibia. Dorsal margin bare, on apex one stout, apically rounded seta. Ventral margin with row of short curved, spine-like setae, on apex two longer, spine-like, pectinate setae. Anterior surface with stout, lanceolate setae along ventral margin. Patellatibial suture present on basal half. Tarsus. Dorsal margin bare. Ventral margin with row of curved, spine-like setae. Claw with one row of 11 or 12 denticles; distally pointed; subapical setae absent.

Middle and hind legs. As foreleg; femur ventrally with few stout, lanceolate setae; tibia dorsal margin with row of stout setae.

Abdominal terga (Fig. 26a). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I–IV(V) smooth, without spines; (V–)VI with rudimentary spines; VII–IX with triangular, pointed spines.

Abdominal sterna. Posterior margin of sterna smooth, without spines.

Tergalii (Fig. 25f). Present on segments I–VII. Margin with small denticles intercalating fine simple setae. Tracheae partly extending from main trunk toward inner and outer margins. Tergalius I as long as length of 2/3 of segment II; Tergalius IV as long as length of segments V and 1/3 VI combined; Tergalius VII as long as segments VIII and 1/3 IX combined.

Paraproct (Fig. 26b). With six or seven stout, marginal spines. Surface scattered with U-shaped scale bases. Cercotractor with numerous small, marginal spines.

Subimaginal gonostyli (Fig. 26c) developing under cuticle of male last instar larvae folded in Nigrobaetis-type (Kluge 2004: fig. 29G).

Adult stages. Unknown.

Eggs (Fig. 27). Ovoid; surface with numerous polygonal structural elements (surface of the eggs in Fig. 27 could be partly degraded; a central, smaller, rounded, slightly elevated area surrounded by a round trench (as in other species) seems to be absent on the polygonal structural element, or invisible due to degradation).

Referring to the island of Sumatra, where the species was collected.

(Fig. 40c). Indonesia, Sumatra.

The specimens were collected at altitudes from 10 m to 1300 m, mostly in deforested or agricultural areas. The streams were in average 2–5 m wide, 15–50 cm deep and flowing with 0.5–0.7 m/s. The substrate was always a mix of substantial amounts of boulder, stones, gravel, and sand.

Holotype. Indonesia • larva; Sumatra, volcano Marapi, West; 00°28'29"S, 100°22'08"E; 553 m; 09.iv.2014; leg. M. Gueuning; on slide; GBIFCH00422020; MZL. Paratypes. Indonesia • 28 larvae; same data as holotype; 1 on slide; GBIFCH00592665; MZL; 27 in alcohol; GBIFCH00419696, GBIFCH00421961, GBIFCH00421976, GBIFCH00421985, GBIFCH00421992, GBIFCH00421997, GBIFCH00422012, GBIFCH00422014, GBIFCH00422016, GBIFCH00422017, GBIFCH00422034, GBIFCH00422435, GBIFCH00422704, GBIFCH00422929, GBIFCH00975675; MZL • 1 larva; Sumatra, volcano Marapi; 00°21'58"S, 100°33'18"E; 890 m; 02.iv.2014, leg. M. Gueuning; in alcohol; GBIFCH00422001; MZL • 1 larva; Sumatra, volcano Marapi, East; 00°21'33"S, 100°30'42"E; 1205 m; 03.iv.2014; leg. M. Gueuning; in alcohol; GBIFCH00422041; MZL • 2 larvae; Sumatra, volcano Sago, North, Riv. Simbukan; 00°17'08"S, 100°41'13"E; 880 m; 18.iii.2014; leg. M. Gueuning; in alcohol; GBIFCH00422027, GBIFCH00422037; MZL • 6 larvae; Sumatra, volcano Sago, South, Riv. Kobun; 00°22'33"S, 100°39'33"E; 1095 m; 19.iii.2014; leg. M. Gueuning; in alcohol; GBIFCH00421959, GBIFCH00421966, GBIFCH00422005, GBIFCH00422025, GBIFCH00422040, GBIFCH00423021; MZL • 2 larvae; Sumatra, volcano Sago, South, Riv. Tampo; 00°22'20"S, 100°41'45"E; 960 m; 20.iii.2014; leg. M. Gueuning; 1 on slide; GBIFCH00422032; 1 in alcohol; GBIFCH00421990; MZL • 1 larva; Sumatra, volcano Singgalang, riv. Caruak, 00°22'56"S, 100°22'42"E; 1300 m; 23.iii.2014; leg. M. Gueuning; in alcohol; GBIFCH00421956; MZL • 1 larva; Sumatra, volcano Singgalang, riv. Sianok; 00°19'57"S, 100°19'19"E; 1150 m; 24.iii.2014; leg. M. Gueuning; on slide; GBIFCH00422030; MZL • 10 larvae; Sumatra, volcano Singgalang, riv. Airjernih; 00°24'07"S, 100°16'44"E; 840 m; 25.iii.2014; leg. M. Gueuning; 1 on slide; GBIFCH00592666; 9 in alcohol; GBIFCH00421960, GBIFCH00421970, GBIFCH00422010, GBIFCH00422018, GBIFCH00422028, GBIFCH00422038, GBIFCH00422973; MZL • 6 larvae; Sumatra, volcano Talamau, South, Riv. Pularian; 00°00'60"N, 100°00'01"E; 540 m; 01.iv.2014; leg. M. Gueuning; 1 on slide; GBIFCH00422013; 5 in alcohol; GBIFCH00421981, GBIFCH00421965, GBIFCH00422004, GBIFCH00422021, GBIFCH00423066; MZL • 1 larva; Sumatra Barat, Sawahlunto, stream; 00°41'20"S, 100°46'43"E; 275.m; 10.xi.2011; leg. M. Balke; (UN5); in alcohol; GBIFCH00975705; MZL • 1 larva; Sumatra, upstream Tarusan; 10 m; 24.v.2010; leg. J.-M. Elouard; in alcohol; GBIFCH00975663; MZL • 1 larva; Sumatra, Batusangkar, Riv. Lupuak Tapuak; 440 m; 27.v.2010; leg. J.-M. Elouard; on slide; GBIFCH00975664; MZL.

Larva. Following combination of characters: A) dorsal surface of labrum with submedian seta and two long, simple setae in submarginal position; length 0.8× width (Fig. 29a–c); B) right mandible: incisor with five denticles, kinetodontium with three denticles (Fig. 29d); C) left mandible: incisor with four denticles, kinetodontium with four denticles; margin between prostheca and mola straight, with row of few short, setae-like processes (Fig. 29e); D) fore femur length ca. 2.4× maximum width, dorsal margin with 7–9 curved, spine-like setae (Fig. 32a); E) tibia dorsally bare, distally with one stout, apically rounded seta (Fig. 32a, c); F) claw with 12–14 denticles (Fig. 32d); G) hind protoptera absent; H) tergalii on abdominal segments I–VII; I) posterior margins of abdominal terga: I smooth, without spines; II–IX with triangular, pointed spines (Fig. 33).

Larva (Figs 28–33). Body length 3.0–3.3 mm. Caudalii broken. Antennae ca. 2.5× head length.

Colouration (Fig. 28a–c). Head dorsally pale brown, thorax, and abdomen dorsally brown, with bright pattern as Fig. 28c. Head, thorax, and abdomen ventrally pale brown. Legs pale brown, femur apically brown and with a brown, distomedial spot. Caudalii brown.

Labrum (Fig. 29a–c). Length 0.8× maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submedian seta and two long, simple, submarginal setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid, pectinate setae.

Right mandible (Fig. 29d). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with five denticles, inner margin of innermost denticle without row of thin setae. Prostheca stick-like, apicolaterally denticulate. Margin between prostheca and mola straight, with row of setae-like processes. Tuft of setae at apex of mola present.

Left mandible (Fig. 29e). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with four denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with row of few short, setae-like processes. Tuft of setae at apex of mola absent.

Hypopharynx and superlinguae (Fig. 30a). Lingua shorter than superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed; distal half laterally not expanded. Superlinguae distally rounded; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 30b–d). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like seta and ca. four long, simple setae. Maxillary palp ca. 1.2× as long as length of galea-lacinia; 2-segmented; palp segment II ca. 1.3× as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment slightly pointed.

Labium (Fig. 31a–f). Glossa basally broad, narrowing toward apex; approx. as long as paraglossa; inner margin with ca. eight spine-like setae; apex with two long and one medium, robust setae; outer margin with ca. six spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and ca. two medium, simple setae in anteromedial area; dorsally with three long, spine-like, simple setae near inner margin. Labial palp with segment I 0.9× length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without protuberance; ventral surface with short, fine, simple setae; dorsally with row of ca. three long, spine-like setae. Segment III slightly pentagonal; length subequal to maximum width; inner apical margin with some setae-like processes (Fig. 31f); ventrally with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera : Absent.

Foreleg (Fig. 32a–d). Ratio of foreleg segments 1.2:1.0:0.9:0.3. Femur. Length ca. 2.4× maximum width. Dorsal margin with 7–9 curved, spine-like setae; length of setae 0.27× maximum width of femur. Apex rounded, with pair of spine-like setae. Medium, stout, lanceolate setae along ventral margin; femoral patch absent. Tibia. Dorsal margin bare, on apex one stout, apically rounded seta. Ventral margin with row of short to medium curved, spine-like setae, on apex two longer, spine-like, pectinate setae. Anterior surface with few stout, lanceolate setae along ventral margin. Patellatibial suture present on basal half. Tarsus. Dorsal margin bare. Ventral margin with row of curved, spine-like setae. Claw with one row of 12–14 denticles; distally pointed; subapical setae absent.

Middle and hind legs. As foreleg.

Abdominal terga (Fig. 33). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I smooth, without spines; II–IX with triangular, pointed spines.

Abdominal sterna. Posterior margin of sterna smooth, without spines.

Tergalii (Fig. 32e). Present on segments I–VII. Margin with small denticles intercalating fine simple setae. Tracheae restricted to main trunk and few branches, not reaching margins. Tergalius I as long as length of segment II; Tergalius IV as long as length of segments V and 1/2 VI combined; Tergalius VII as long as segments VIII and 1/2 IX combined.

Paraproct. With six or seven stout, marginal spines. Surface scattered with U-shaped scale bases, fine, simple setae, and micropores. Cercotractor with numerous small, marginal spines.

Adult stages. Unknown.

Referring to the island of Borneo, where the species was collected.

(Fig. 40c). Indonesia, Borneo (East Kalimantan).

The specimens were collected at an altitude of 160 m in a large (width ca. 36 m), shallow (depth ca. 0.1 m), fast flowing (ca. 0.9 m/s) stream. The stream was characterised by equally run/riffles and pools. Water temperature was 25 °C, substrate was dominated by boulder and cobble.

Holotype. Indonesia • larva; East Kalimantan, Bas. Malinau, riv. Seturan, loc. Seturan (2001-block 57), trib. Bengahau; 02°59'22"N, 116°30'46"E; 08.viii.2000; leg. P. Derleth; on slide; GBIFCH00592663; MZL. Paratypes. Indonesia • 3 larvae; same data as holotype; 1 on slide; GBIFCH00975692; 2 in alcohol; GBIFCH00975674; MZL.

Larva. Following combination of characters: A) dorsal surface of labrum with submedian seta and a short, submarginal arc of three long, simple setae (Fig. 35b); B) right mandible: incisor with four denticles, kinetodontium with four denticles (Fig. 35c); C) left mandible: incisor with four or five denticles, kinetodontium with three denticles; margin between prostheca and mola straight, with row of few short, setae-like processes (Fig. 35d); D) fore femur length ca. 3× maximum width, dorsal margin with 7–9 curved, spine-like setae (Fig. 38a); E) tibia dorsally with row of spine-like, apically rounded setae; distally with one stout, apically rounded seta (Fig. 38a, b); F) claw with ten or eleven denticles (Fig. 38e); G) hind protoptera absent; H) tergalii on abdominal segments I–VII; I) posterior margins of abdominal terga: I–V (IV) smooth, without spines; (V) VI–IX with triangular, pointed spines (Fig. 39a).

Larva (Figs 34–39). Body length 3.5–4.6 mm. Caudalii broken. Antennae ca. 3× head length.

Colouration (Fig. 34a–c). Head, thorax, and abdomen dorsally brown, abdominal terga VI and VII darker, abdominal terga VIII and IX pale brown. Head, thorax, and abdomen ventrally pale brown. Legs brown, femur mediobasally with bright area. Caudalii brown.

Labrum (Fig. 35a, b). Length 0.7× maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submedian seta and several long, simple, submarginal setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid, pectinate setae.

Right mandible (Fig. 35c). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with four denticles, inner margin of innermost denticle without row of thin setae. Prostheca stick-like, apicolaterally denticulate. Margin between prostheca and mola straight, with row of setae-like processes. Tuft of setae at apex of mola present.

Left mandible (Fig. 35d). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with row of short, setae-like processes. Tuft of setae at apex of mola absent.

Hypopharynx and superlinguae (Fig. 36a). Lingua shorter than superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed; distal half laterally slightly expanded. Superlinguae distally rounded; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 36b–d). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like, pectinate seta and ca. five long, simple setae. Maxillary palp ca. 1.3× as long as length of galea-lacinia; 2-segmented; palp segment II approx. as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment slightly pointed.

Labium (Fig. 37a–f). Glossa basally broad, narrowing toward apex; approx. as long as paraglossa; inner margin with ca. seven spine-like setae; apex with two long and one medium, robust setae; outer margin with ca. six spine-like setae; ventral surface with row of fine, simple, setae along inner margin. Paraglossa curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and ca. three medium, simple setae in distal area; dorsally with three long, spine-like, simple setae near inner margin. Labial palp with segment I slightly longer than segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without protuberance; ventral surface with short, fine, simple setae; dorsally with row of ca. four long, spine-like setae. Segment III slightly pentagonal; length ca. 1.2× maximum width; inner apical margin with some setae-like processes (Fig. 37f); ventrally with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera : Absent.

Foreleg (Fig. 38a–e). Ratio of foreleg segments 1.3:1.0:0.7:0.2. Femur. Length ca. 3× maximum width. Dorsal margin with 7–9 curved, spine-like setae; length of setae 0.31× maximum width of femur. Apex rounded, with pair of spine-like setae. Medium, stout, lanceolate setae along ventral margin; femoral patch absent. Tibia. Dorsal margin with row of spine-like, apically rounded setae; on apex one stout, apically rounded seta. Ventral margin with row of short, curved, spine-like setae; on apex two longer, spine-like, pectinate setae. Anterior surface with stout, lanceolate, slightly pectinate setae along ventral margin. Patellatibial suture present on basal half. Tarsus. Dorsal margin bare. Ventral margin with row of curved, spine-like, pectinate setae. Claw with one row of ten or eleven denticles; distally pointed; subapical setae absent.

Middle and hind legs. As foreleg.

Abdominal terga (Fig. 39a). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I–V (IV) smooth, without spines; (V) VI–IX with triangular, pointed spines.

Abdominal sterna. Posterior margin of sterna smooth, without spines.

Tergalii (Fig. 38f). Present on segments I–VII. Margin with small denticles intercalating fine simple setae. Tracheae restricted to main trunk and few branches, not reaching margins. Tergalius I as long as length of segment II; Tergalius IV as long as length of segments V and 1/3 VI combined; Tergalius VII as long as segments VIII and IX combined.

Paraproct. With six or seven stout, marginal spines. Surface scattered with U-shaped scale bases and micropores. Cercotractor with numerous small, marginal spines.

Adult stages. Unknown.

Eggs (Fig. 40a, b). Egg of Fig. 40a still in early stage of development, probably not showing the final shape (see Fig. 40b, pack of developing eggs extracted from same larva). Surface with numerous papillae-like structural elements (polygonal to rounded structure, centrally with a smaller, rounded, slightly elevated area surrounded by a round trench).

Referring to the province Kalimantan (Indonesia, Borneo), where the species was collected.

(Fig. 40c). Indonesia, Borneo (East Kalimantan).

The specimens were collected on altitudes of ca. 130 m. The streams were 2–30 m wide, ca. 0.1 m deep, and flowing with ca. 0.6 m/s. The location was dominated by riffles and run, substrate was mainly gravel and cobble, water temperature ca. 26 °C.

Holotype. Indonesia • larva; East Kalimantan, Bas. Malinau, riv. Seturan, loc. Seturan, main river; 116°30'48"E, 03°00'05"N, 28.iii.2001; leg. P. Derleth and B. Feldmeyer; on slide; GBIFCH00592661; MZL. Paratypes. Indonesia • 3 larvae; same data as holotype; 2 on slides; GBIFCH00592655, GBIFCH00592662; MZL • 2 larvae; East Kalimantan, Bas. Malinau, Riv. Seturan, Loc. Seturan (1999-bloc 39–40), Trib. Temalat (Sungai Guang); 03°00'10"N, 116°32'24"E; 27.iii.2001; leg. P. Derleth; in alcohol; GBIFCH00975671; MZL • 2 larvae; East Kalimantan, Bas. Malinau, Riv. Seturan, Loc. Seturan (2001-bloc 57), Trib. Tamalang (Sungai Guang); 18.vii.2001; leg. P. Derleth and F. Béboux; 1 on slide; GBIFCH00592614; 1 in alcohol; GBIFCH00975683; MZL • 5 larvae; East Kalimantan, Bas. Malinau, Riv. Seturan, Loc. Seturan (2001-bloc 57), Trib. Tamalang (Sungai Guang); 10.iv.2001; leg. P. Derleth; in alcohol; GBIFCH00975684, GBIFCH00975685; MZL • 2 larvae; East Kalimantan, Bas. Malinau, riv. Rian, loc. Langap South (1997-bloc 6), trib. Belakau; 116°30'26"E, 3°04'04"N; 18.iv.2001; leg. P. Derleth and M. Sartori; in alcohol; GBIFCH00975672; MZL • 1 larva; East Kalimantan, Bas. Malinau, riv. Seturan, loc. Seturan (2000-bloc 43), trib. Temalat (Sungai Guang); 116°33'29"E, 02°59'29"N; 16.viii.2000; leg. P. Derleth and R. Schlaepfer; in alcohol; GBIFCH00975673; MZL • 3 larvae; East Kalimantan, Bas. Malinau, Riv. Rian, Loc. Langap Sud (1995), Trib. Ngayo; 03°04'56"N, 116°30'58"E; 17.iv.2001; leg. P. Derleth and M. Sartori; 2 on slides; GBIFCH00592656, GBIFCH00975691; 1 in alcohol; GBIFCH00975693; MZL.