Labiobaetis pangantihoni, 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 pangantihoni sp. nov. Figures 19 , 20 , 43b , 49a

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of one plus nine or ten long, feathered setae; B) labial palp segment II with a rather slender, thumb-like distomedial protuberance, segment III slightly pentagonal; C) fore femur rather broad, length 3.4 × maximum width, dorsal margin with eleven or 12 curved, spine-like setae; D) claw with 10-13 denticles; E) paraproct distally not expanded, with ca. 16 stout marginal spines.

Description.

Larva (Figs 19 , 20 , 43b ). Body length 3.5-4 mm. Cerci ca. 2/3 of body length. Paracercus ca. 2/3 of cerci length. Antenna approx. 2.5 × as long as head length.

Colouration. Head, thorax, and abdomen dorsally brown, with bright pattern as in Fig. 43b , fore protoptera brown with bright striation. Head, thorax, and abdomen ventrally light brown, genae brown, abdominal segments VIII and IX darker brown. Legs light brown, femur with distomedial brown spot, apex brown, tibia distally brown. Caudalii light brown with a brown band at ca. 1/3 of cerci length.

Antenna (Fig. 20f ) with scape and pedicel subcylindrical, with well-developed distolateral process at scape.

Labrum (Fig. 19a ). 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 nine or ten long, feathered setae. Ventrally with marginal row of setae composed of lateral and 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. 19b, c ). Incisor and kinetodontium fused. Incisor with five denticles; kinetodontium with three denticles, inner margin of innermost denticle without 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. 19d, e ). 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. 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. 19f ). 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. 19g ). 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 or five long, simple setae. Maxillary palp 1.3 × as long as length of galea-lacinia; 2-segmented; palp segment II 1.3 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment rounded, with excavation at inner distolateral margin.

Labium (Fig. 19h, i ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ca. eight spine-like setae, distalmost seta much longer than other setae; apex with two long and one medium, robust, pectinate setae; outer margin with six medium to long, spine-like setae; ventral surface with short, fine, simple, scattered setae. Paraglossa sub-rectangular, 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 a row of four 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 with rather slender, thumb-like distomedial protuberance; distomedial protuberance 0.8 × width of base of segment III; ventral surface with short, fine, simple setae; dorsally with a row of four spine-like, simple setae near outer margin. Segment III slightly pentagonal; apex slightly truncate; length 1.1 × width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 20g ) well developed.

Foreleg (Fig. 20a, b ). Ratio of foreleg segments 1.2:1.0:0.6:0.2. Femur. Length ca. 3 × maximum width. Dorsal margin with eleven or twelve curved, spine-like setae; length of setae 0.16 × 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, near margin another row of short, spine-like setae. Ventral margin with row of short to medium, curved, spine-like setae, on apex some longer and partly bipectinate 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 stout setae and fine, simple setae. Ventral margin with a row of curved, spine-like setae. Claw with one row of 10-13 denticles; distally pointed; with ca. four stripes; subapical setae absent.

Terga (Fig. 20c ). 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. 20d ). 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. 1/2 length of segment II. Gill IV as long as length of segments V and 1/2 VI combined. Gill VII as long as length of segments VIII and 1/4 IX combined.

Paraproct (Fig. 20e ). Distally not expanded, with ca. 16 stout, marginal spines. Surface scattered with U-shaped scale bases, fine, simple setae and micropores. Cercotractor with numerous small, marginal spines.

Etymology.

Dedicated to Mr. Clister V. Pangantihon, outstanding collector, entomologist and project assistant of the AdMU Biodiversity Laboratory.

Distribution.

Philippines: Palawan (Fig. 49a ).

Biological aspects.

The specimens were collected at altitudes from sea level to 180 m, partly on submerged wood in runs or riffles.

Type material.

Holotype. Philippines • larva; Palawan, Balabac, Danglis River near the road; 07°57'39"N, 117°02'59"E; 170 m; 2019; leg. Pelingen and Pangantihon; on slide; GBIFCH 00592336; PNM. Paratypes. Philippines • 9 larvae; same data as holotype; 3 on slides; GenBank: MT830959; GBIFCH 00592321, GBIFCH 00763684, GBIFCH 00592335; ZSM, temporarily stored in AdMU; 5 in alcohol; GBIFCH 00515426; PCSD; 1 in alcohol; GBIFCH 00515400; AdMU • 1 larva; Palawan, Balabac, Danglis Falls/Busay; 07°57'39"N, 117°02'59"E; 180 m; 2019; leg. Pelingen and Pangantihon; in alcohol; GBIFCH 00515427; AdMU • 5 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 00592331; AdMU; 2 in alcohol; GBIFCH 00515429; PNM; 2 in alcohol; GBIFCH 00515401, GBIFCH 00515402; AdMU • 2 larvae; Palawan, Quezon, Aramaywan River; 09°18'25"N, 118°07'42"E; 20 m; 2019; leg. Pangantihon and Pelingen; in alcohol; GBIFCH 00515428; AdMU.

Figures

Figure 19. Labiobaetis pangantihoni 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 i apex of paraglossa.

Figure 20. Labiobaetis pangantihoni 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.