Labiobaetis acei, Kaltenbach & Garces & Gattolliat, 2020

Kaltenbach, Thomas, Garces, Jhoana M. & Gattolliat, Jean-Luc, 2020, The success story of Labiobaetis Novikova & Kluge in the Philippines (Ephemeroptera, Baetidae), with description of 18 new species, ZooKeys 1002, pp. 1-114 : 1

Labiobaetis acei sp. nov. Figures 5 , 6 , 41b , 46a , 48c

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of six or seven long, simple setae; B) labial palp segment II with a thumb-like distomedial protuberance, segment III conical; C) left mandible with a comb-shaped structure at base of mola; D) fore femur rather broad, length ca. 3 × maximum width, dorsal margin with 9-12 curved, spine-like setae and a partial second row near margin; E) tergum IV with rounded, partly fused spines at posterior margin, surface with irregular, dense rows of U-shaped scale bases; F) paraproct distally not expanded, with 29-34 stout, marginal spines.

Description.

Larva (Figs 5 , 6 , 41b , 46a ). Body length 4.2-10.3 mm. Cerci ca. 2/3 of body length. Paracercus ca. 2/3 of cerci length. Antenna approx. twice as long as head length.

Colouration. Head, thorax, and abdomen dorsally brown, with pattern as in Fig. 41b . Fore protoptera brown with dark brown striation. Head, thorax, and abdomen ventrally brown, abdominal segment IX ecru (Fig. 46a ). Legs light brown, femur with a distomedial brown spot and a brown apex. Caudalii light brown with a dark brown band at ca. 1/3 of cerci length.

Antenna (Fig. 6f ) with scape and pedicel subcylindrical, without distolateral process at scape.

Labrum (Fig. 5a ). 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 one plus six or seven long, simple setae, the first two setae after the submedian seta are close together. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with ca. five short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 5b, c ). Incisor and kinetodontium fused. Incisor with five denticles; kinetodontium with three denticles, inner margin of innermost denticle with a row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola with a pronounced hump. Tuft of setae at apex of mola present and many thin setae distally at base of mola.

Left mandible (Fig. 5d-g ). Incisor and kinetodontium fused. Incisor with three denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola slightly convex, with minute denticles toward 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. Comb-shaped structure at base of mola present.

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

Hypopharynx and superlinguae (Fig. 5h ). Lingua approx. as long as superlinguae. Lingua longer than broad; medial tuft of stout setae well developed, short; distal half laterally expanded. Superlinguae distally rounded; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 5i ). Galea-lacinia ventrally with two simple, apical setae under 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 bipectinate, spine-like seta and 5-7 medium to long, simple setae. Maxillary palp 1.4 × as long as length of galea-lacinia; 2-segmented; palp segment II 1.4 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment slightly pointed, without excavation at inner distolateral margin.

Labium (Fig. 5j ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ca. ten short, stout, spine-like setae plus distalmost one much longer, less robust, spine-like seta; apex with two long and one medium, robust, pectinate setae and one short, robust seta; outer margin with six spine-like setae increasing in length distally; ventral surface with fine, simple, scattered setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and four or five medium, simple setae in anteromedial area; outer margin with some long, spine-like setae; dorsally with a row of six long, spine-like 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 with thumb-like distomedial protuberance; distomedial protuberance 0.5 × width of base of segment III; ventral surface with short, fine, simple setae; dorsally with a row of 7-9 medium, spine-like, simple setae near outer margin. Segment III conical; apex slightly pointed; length 1.0 × width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 6g ) minute.

Foreleg (Fig. 6a, b ). Ratio of foreleg segments 1.4:1.0:0.8:0.2. Femur. Length ca. 3 × maximum width. Dorsal margin with a row of 9-12 curved, spine-like setae, a partial row of spine-like setae and some additional spine-like setae near margin; length of setae 0.16 × maximum width of femur. Apex rounded, with a pair of curved, spine-like setae and some short, stout setae. Many stout, lanceolate setae scattered along ventral margin; femoral patch absent. Tibia. Dorsal margin with a row of short to medium, spine-like setae and fine, simple setae, on apex two longer, spine-like setae. Ventral margin with a row of short to medium curved, spine-like setae, distally of patellotibial suture one longer, curved, spine-like seta, on apex some longer, partly bipectinate, spine-like setae and a tuft of fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Patellotibial suture present on basal half. Tarsus. Dorsal margin with a row of short, spine-like setae and fine, simple setae. Ventral margin with a row of curved, spine-like setae. Claw with one row of 12-14 denticles; distally pointed; with ca. five stripes; subapical setae absent.

Terga (Fig. 6c ). Surface with dense, irregular rows of U-shaped scale bases. Posterior margin of tergum IV with rounded, partly fused spines, wider than long.

Gills (Fig. 6d ). 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 VI combined. Gill VII as long as length of segments VIII and half of IX combined.

Paraproct (Fig. 6e ). Distally not expanded, with 29-34 stout, marginal spines. Surface scattered with U-shaped scale bases. Cercotractor with numerous small, marginal spines.

Etymology.

Dedicated to Mr. Ace Kevin Amarga (Philippines/Taiwan), an outstanding collector and entomologist, for loaning some precious material to one of the authors (JG).

Distribution.

Philippines: Luzon (Fig. 48c ).

Biological aspects.

The specimens were collected at altitudes of 1700 m and 1820 m, either on rock surface or bottom gravel in riffles or runs, or in root packs or grass bunches in riffles or runs.

Type material.

Holotype. Philippines • larva; Luzon, Mountain Province, Bauko, mineral rich mountain creek; 17°03'53"N, 121°05'10"E; 1820 m; XI.1997; leg. Mey; on slide; GenBank: MT830941; GBIFCH 00763643; PNM. Paratypes. Philippines • 41 larvae; same data as holotype; 2 on slides; GBIFCH 00592360, GBIFCH 00592361; MZL; 13 in alcohol; GBIFCH 00515445; MZL; 25 in alcohol; GBIFCH 00515449; AdMU; 1 in alcohol; GBIFCH 00515452; MZL • 64 larvae; Luzon, Ifugao, Banaue, Sumigar Bridge; 16°59'37"N, 121°02'51"E; 1700 m; IX.1997; leg. Mey; 3 on slides; GenBank: MT830942, MT830943; GBIFCH 00592329, GBIFCH 00763645, GBIFCH 00763651; MZL; 31 in alcohol; GBIFCH 00515446, GBIFCH 00515447, GBIFCH 00515453; MZL; 30 in alcohol; GBIFCH 00515448, GBIFCH 00515450; AdMU.

Figures

Figure 5. Labiobaetis acei sp. nov., larva morphology a labrum b right mandible c right prostheca d left mandible e left prostheca f detail of left mola g comb-shaped structure at left mola h hypopharynx and superlinguae i maxilla j labium.

Figure 6. Labiobaetis acei sp. nov., larva morphology a foreleg b fore claw c tergum IV d gill IV e paraproct f antennal scape g metanotum.

Figure 41. Habitus, larvae, dorsal view a Labiobaetis dalisay sp. nov. b Labiobaetis acei sp. nov. c Labiobaetis aldabae sp. nov.

Figure 46. Habitus, larvae, ventral view a Labiobaetis acei sp. nov. b Labiobaetis aldabae sp. nov. c Labiobaetis camiguinensis sp. nov.

Figure 48. Distribution of Labiobaetis in the Philippines a Philippines, overview b Group Labiobaetis dendrisetis c Group Labiobaetis numeratus.