Labiobaetis gamay, 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 gamay sp. nov. Figures 17 , 18 , 43a , 49a

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of one plus 7-9 feathered setae with strongly reduced feathers; B) labial palp segment II with a broad, thumb-like distomedial protuberance; segment III conical; C) fore femur rather broad, length ca. 3 × maximum width, dorsal margin with 10-14 curved, spine-like setae; D) hind protoptera well developed; E) paraproct distally not expanded, with 19-22 stout marginal spines.

Description.

Larva (Figs 17 , 18 , 43a ). Body length 4.6-5.2 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 grey-brown, with bright pattern as in Fig. 43a , abdominal tergites I, VII, and X mainly light brown. Fore protoptera light brown with darker striation. Head, thorax, and abdomen ventrally ecru, frons and genae grey-brown, abdominal sternites VIII and IX grey-brown. Legs ecru, femur with two sometimes merged grey-brown distomedial spots, tarsus distally grey-brown. Caudalii light brown, with a grey- brown band at ca. 1/3 of cerci, cerci distally grey-brown.

Antenna (Fig. 18f ) with scape and pedicel subcylindrical, with well-developed distolateral process at scape.

Labrum (Fig. 17a, b ). 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 7-9 long, feathered setae with strongly reduced feathers. 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. 17c, d ). Incisor and kinetodontium fused. Incisor with four 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. Tuft of setae at apex of mola present.

Left mandible (Fig. 17e, f ). 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 few minute denticles. 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 and superlinguae (Fig. 17g ). 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. 17h ). 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 long, simple setae. Maxillary palp slightly longer than 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 rounded, with slight excavation at inner distolateral margin.

Labium (Fig. 17i ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ca. nine spine-like setae, distalmost seta much longer than other setae; apex with two long and one medium, robust, pectinate setae and one short, robust seta; outer margin with seven 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 one or two medium, simple setae in anteromedial area; dorsally with a row of five long, spine-like, simple 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 broad thumb-like distomedial protuberance; distomedial protuberance 0.7 × width of base of segment III; ventral surface with short, fine, simple setae; dorsally with a row of three long, spine-like setae near outer margin. Segment III conical; apex slightly truncate; length 1.1 × width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 18g ) well developed.

Foreleg (Fig. 18a, b ). Ratio of foreleg segments 1.4:1.0:0.8:0.3. Femur. Length ca. 3 × maximum width. Dorsal margin with 10-14 curved, spine-like setae, mostly one or two setae additionally near margin in basal area; length of setae 0.19 × maximum width of femur. Apex rounded, with a pair of 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, spine-like setae and fine simple setae, on apex one longer, spine-like seta. 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 2/3. Tarsus. Dorsal margin with a row of short, stout setae and fine, simple setae. Ventral margin with a row of curved, spine-like setae and in distal area fine simple setae. Claw with one row of 12 or 13 denticles; distally pointed; with ca. four stripes; subapical setae absent.

Terga (Fig. 18c ). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae. Posterior margin of tergum IV with triangular spines, wider than long.

Gills (Fig. 18d ). Present on segments I-VII. Margin with small denticles intercalating fine simple setae. Tracheae extending from main trunk to inner and outer margins. Gill I ca. 2/3 length of segment II. Gill IV as long as length of segments V and ½ VI combined. Gill VII as long as length of segment VIII.

Paraproct (Fig. 18e ). Distally not expanded, with 19-22 stout, marginal spines. Surface scattered with U-shaped scale bases and fine, simple setae. Cercotractor with numerous small, marginal spines.

Etymology.

Named after the Cebuano word meaning reduced, referring to the strongly reduced feathers of the submarginal setae on the dorsal labrum surface.

Distribution.

Philippines: Luzon and Mindoro (Fig. 49a ).

Biological aspects.

The specimens were collected at altitudes from sea level to 140 m, partly on hygropetric rocks or rock surface in riffles or runs.

Type material.

Holotype. Philippines • larva; Oriental Mindoro, Roxas, Brgy. San Vicente, lower reach of Taugad River; 12°37.30'N, 121°22.97'E; 140 m; 2016-2019; leg. Freitag and Garces; on slide; GBIFCH 00592274; PNM. Paratypes. Philippines • 27 larvae; same data as holotype; 2 on slide; GenBank. MT830953, MT830954; GBIFCH 00 654922, GBIFCH 00763637; ZSM; 25 in alcohol; GBIFCH 00515433, GBIFCH 00515434, GBIFCH 00515458, GBIFCH 00515460; ZSM • 10 larvae; Oriental Mindoro, Roxas, Brgy. San Vicente; 12°37'06"N, 121°23'49"E; 140 m; 2016-2019; leg. Freitag, Garces and Pangantihon; 2 on slides; GenBank: MT830955; GBIFCH 00763639, GBIFCH 00763338; AdMU; 8 in alcohol; GBIFCH 00515435, GBIFCH 00515459; AdMU • 15 larvae; Luzon, La Union, Sudipen Municipality, Amburayan River; 16°54'38"N, 120°28'40"E; 20 m; 14.IV.2019; leg. Freitag, Garces and Pangantihon; 1 on slide; GenBank: MT830956; GBIFCH 00763655; ZSM; 14 in alcohol; GBIFCH 00515436, GBIFCH 00515461; ZSM • 31 larvae; Luzon, Ilocos Sur, Suyo Municipality, big river downstream Sangbay n. Ragsak; 16°59'32"N, 120°32'21"E; 100 m; 15.IV.2019; leg. Freitag, Garces and Pangantihon; 1 on slide; GenBank: MT830957; GBIFCH 00763657; ZSM; 30 in alcohol; GBIFCH 00515437; ZSM • 14 larvae; Luzon, La Union, San Juan Municipality, Baroro River; 16°39'27"N, 120°25'55"E; 90 m; 19.IV.1996; leg. Mendoza; 1 on slide; GenBank: MT830958; GBIFCH 00763658; ZSM; 13 in alcohol; GBIFCH 00515438, GBIFCH 515439; ZSM.

Figures

Figure 17. Labiobaetis gamay sp. nov., larva morphology a labrum b setae of arc on dorsal surface of labrum c right mandible d right prostheca e left mandible f left prostheca g hypopharynx and superlinguae h maxilla i labium.

Figure 18. Labiobaetis gamay sp. nov., larva morphology a foreleg b fore claw c tergum IV d gill IV e paraproct f antennal scape g metanotum.

Figure 43. Habitus, larvae, dorsal view a Labiobaetis gamay sp. nov. b Labiobaetis pangantihoni sp. nov. c Labiobaetis tagbanwa sp. nov.

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