Labiobaetis freitagi, 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 freitagi sp. nov. Figures 33 , 34 , 45a , 49b

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of ca. 17 long, clavate setae; B) labial palp segment II with a thumb-like distomedial protuberance, segment III sub-rectangular; C) left mandible without setae at apex of mola; D) fore femur rather slender, length 3.6 × maximum width, dorsal margin with ca. ten curved, spine-like setae; E) paraproct distally expanded, with 39-46 stout, marginal spines.

Description.

Larva (Figs 33 , 34 , 45a ). Body length 3.1-4.8 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 light brown, fore protoptera light brown with bright striation. Head, thorax, and abdomen ventrally light brown, genae brown. Legs light brown, femur with a distomedial brown spot, dorsal and ventral margin and apex brown. Caudalii light brown.

Antenna (Fig. 34g ) with scape and pedicel subcylindrical, without distolateral process at scape.

Labrum (Fig. 33a ). Rectangular, length 0.7 × maximum width. Distal margin with medial emargination and a small process. Dorsally with medium to long, fine, simple setae scattered over surface; submarginal arc of setae composed of 16 or17 long, clavate setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid setae; ventral surface with ca. four short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 33b, 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 slightly convex, with minute denticles. Tuft of setae at apex of mola present.

Left mandible (Fig. 33d, e ). Incisor and kinetodontium fused. Incisor with five denticles; kinetodontium with three denticles. Prostheca robust, apically with small denticles and comb-shaped 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 absent.

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

Hypopharynx and superlinguae (Fig. 33f ). Lingua shorter than superlinguae. Lingua longer than broad; medial tuft of stout setae well developed; distal half laterally expanded. Superlinguae distally slightly concave; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 33g ). 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 four medium to long, simple setae. Maxillary palp 1.7 × as long as length of galea-lacinia; 2-segmented; palp segment II 1.5 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment rounded, with slight excavation at inner distolateral margin.

Labium (Fig. 33h ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ca. five spine-like setae increasing in length distally; apex with two long and one medium, robust, pectinate setae; outer margin with four spine-like setae; 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 a row of three or four medium, simple setae in anteromedial area; dorsally with a row of three long, spine-like setae near inner margin. Labial palp with segment I 0.8 × length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II with thumb-like distomedial protuberance; distomedial protuberance 0.8 × width of base of segment III; ventral surface with short, fine, simple setae; dorsally with one long, spine-like seta near outer margin. Segment III subrectangular; apex rounded; length 1.0 × width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera absent.

Foreleg (Fig. 34a-c ). Ratio of foreleg segments 1.2:1.0:0.6:0.2. Femur. Length ca. 4 × maximum width. Dorsal margin with ten or eleven long, curved, spine-like setae; length of setae 0.25 × maximum width of femur. Apex rounded, with a pair of long, curved, spine-like setae and some short stout and fine, simple setae. Many stout, lanceolate setae scattered along ventral margin; femoral patch absent. Tibia. Dorsal margin sometimes with a row of spine-like setae and always with a row of fine, simple setae, on apex two longer, spine-like setae. Ventral margin with a row of short, curved, spine-like setae, on apex some longer, partly bipectinate setae and a tuft of fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Patellotibial suture present on basal 1/3. Tarsus. Dorsal margin with a row of fine, simple setae. Ventral margin with a row of curved, spine-like setae. Claw with one row of ten or eleven denticles; distally pointed; with ca. three stripes; subapical setae absent.

Terga (Fig. 34d ). Surface with irregular rows of U-shaped scale bases. Posterior margin of tergum IV with triangular spines, wider than long.

Gills (Fig. 34e ). Present on segments II-VII. Margin with small denticles intercalating fine simple setae. Tracheae partly extending from main trunk to inner and outer margins, pigmentation mainly limited to main trunk. Gill IV as long as length of segments V and 1/3 VI combined. Gill VII as long as length of segment VIII.

Paraproct (Fig. 34f ). Distally expanded with 39-46 stout, marginal spines. Surface scattered with U-shaped scale bases. Cercotractor with numerous small, marginal spines.

Etymology.

Dedicated to Prof. Hendrik Freitag (Philippines/Germany), collector of some material, for his outstanding contribution to freshwater biodiversity research in Southeast Asia.

Distribution.

Philippines: Palawan (Fig. 49b ).

Biological aspects.

The specimens were collected at altitudes from sea level to 150 m, in leaf packs or submerged wood in runs or riffles.

Type material.

Holotype. Philippines • larva; Palawan, Brooke’s Point, Mainit 7 Falls; 08°51'48"N, 117°47'45"E; 150 m; 2019; leg. Pelingen and Pangantihon; on slide; GBIFCH 00592322; PNM. Paratypes. Philippines • 22 larvae; same data as holotype; in alcohol; GenBank: MT830978; GBIFCH 00515497, GBIFCH 00763677; AdMU • 7 larvae; Palawan, P.Princesa Cabayugan District, Cabayugan River, near Nagsatayan Creek, S of Martarpi; 10°09'47"N, 118°50'37"E; 37 m; 05.VIII.2000; leg. Freitag; 1 on slide; GenBank: MT830978; GBIFCH 00763678; ZSM, temporarily stored in AdMU; 6 in alcohol; GBIFCH 00515498; PNM • 11 larvae; Palawan, Quezon, Isugod, Aramaywan River; 09°21'07"N, 118°08'26"E; 14 m; 2019; leg. Pangantihon and Pelingen; 1 on slide; GBIFCH 00592332; AdMU; 1 on slide; GBIFCH 00592333; ZSM, temporarily stored in AdMU; 6 in alcohol; GBIFCH 00515496; AdMU; 3 in alcohol; GenBank: MT830980; GBIFCH 00763682, GBIFCH 00515456; ZSM, temporarily stored in AdMU • 10 larvae; Palawan, Balabac, Suray River, Indalawan, near the road; 07°57'01"N, 117°04'29"E; 16 m; 2019; leg. Pangantihon and Pelingen; in alcohol; GenBank: MT830981; GBIFCH 00763683, GBIFCH 00515499; PCSD.

Figures

Figure 33. Labiobaetis freitagi sp. nov., larva morphology a labrum b right mandible c right prostheca d left mandible e left prostheca f hypopharynx and superlinguae g maxilla h labium.

Figure 34. Labiobaetis freitagi sp. nov., larva morphology a foreleg b fore tibia c fore claw d tergum IV e gill IV f paraproct g antennal scape.

Figure 45. Habitus, larvae, dorsal view a Labiobaetis freitagi sp. nov. b Labiobaetis pelingeni sp. nov. c Labiobaetis giselae sp. nov. d Labiobaetis mendozai sp. nov.

Figure 49. Distribution of Labiobaetis in the Philippines a Group Labiobaetis operosus b Group Labiobaetis sumigarensis c Group Labiobaetis vallus.