Labiobaetis palawano, 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 palawano sp. nov. Figures 13 , 14 , 42c , 47b , 48c

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of one plus seven long, simple setae; B) labial palp segment II with a thumb-like distomedial protuberance, segment III conical; C) mola of right mandible proximally beginning with a double hump; D) hypopharynx with medial tuft of stout setae poorly developed; E) fore femur rather broad, length ca. 3 × maximum width, dorsal margin with 10-13 curved, spine-like setae and a partial second row near margin; F) claw with 15-17 denticles; G) posterior margin of tergum IV with rounded spines, wider than long.

Description.

Larva (Figs 13 , 14 , 42c , 47b ). Body length 3-4 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 dark brown markings as in Fig. 42c . Fore protoptera light brown with brown striation. Head, thorax, and abdomen ventrally brown. Legs light brown, femur with a distomedial brown spot, apically brown. Caudalii light brown, with a brown band at ca. 1/3 of cerci.

Antenna (Fig. 14f ) with scape and pedicel subcylindrical, without distolateral process at scape.

Labrum (Fig. 13a ). 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 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. eight short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 13b, 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, mola proximally beginning with a double hump. Tuft of setae at apex of mola present and many thin setae distally at base of mola.

Left mandible (Fig. 13d-f ). 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 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 and partly with minute secondary dentation at the tips. Tuft of setae at apex of mola present. Comb-shaped structure at base of mola present.

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

Hypopharynx and superlinguae (Fig. 13g ). Lingua longer than superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed; distal half not expanded. Superlinguae distally straight; lateral margin angulate; fine, long, simple setae along distal margin.

Maxilla (Fig. 13h ). 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 1.2 × 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. 13i ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ca. nine short, stout, spine-like setae plus distalmost one much longer, less robust, spine-like seta; apex with two long, one medium and one short, 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 3-5 medium, simple setae in anteromedial area and one fine, simple seta in proximomedial area; outer margin with some long, spine-like setae; 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 and one short, stout, simple seta at inner margin. Segment II with thumb-like distomedial protuberance; distomedial protuberance 0.6 × width of base of segment III; ventral surface with short, fine, simple setae; dorsally with a row of seven medium, spine-like, simple setae near outer margin. Segment III conical; apex slightly truncate; length 1.0 × width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 14g ) minute.

Foreleg (Fig. 14a, b ). Ratio of foreleg segments 1.4:1.0:0.8:0.3. Femur. Length ca. 3 × maximum width. Dorsal margin with a row of 10-13 curved, spine-like setae in different length, and a partial second row of spine-like setae near margin; length of setae 0.28 × maximum width of femur. Apex rounded, with a pair of curved, spine-like setae and some short, stout, apically rounded setae. Many stout, lanceolate setae scattered along ventral margin; femoral patch absent. Tibia. Dorsal margin with a row of short, spine-like setae, on apex one longer, spine-like seta. Ventral margin with a row of short to long, curved, spine-like setae, distally of patellotibial suture one long, curved, spine-like seta, on apex some longer, curved, 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, stout setae. Ventral margin with a row of curved, spine-like setae. Claw with one row of 15-17 denticles; distally pointed; with 5-8 stripes; subapical setae absent.

Terga (Fig. 14c ). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae and micropores. Posterior margin of tergum IV with rounded, partly fused spines, wider than long.

Gills (Fig. 14d ). 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 ½ VI combined. Gill VII as long as length of segments VIII and 1/3 IX combined.

Paraproct (Fig. 14e ). Distally not expanded, with ca. 17 stout, marginal spines and some submarginal spines. Surface scattered with U-shaped scale bases, fine, simple setae and micropores. Cercotractor with numerous small, marginal spines.

Etymology.

Dedicated to the indigenous Palawano people of Palawan.

Distribution.

Philippines: Palawan (incl. Busuanga) (Fig. 48c ).

Biological aspects.

The specimens were collected at altitudes below 100 m, partly on rock surface in riffles or runs.

Type material.

Holotype. Philippines • larva; Palawan, P. Princesa, Bindujan, Talabigan River; 10°01'26"N, 119°04'37"E; 10 m; 27.VII.2019; leg. Freitag and Molls; on slide; GenBank: MT830987; GBIFCH 00763688; PNM. Paratypes. Philippines • 2 larvae; Palawan, Busuanga, Coron, 4 km E San Nicolas; 12°03'46"N, 120°13'25"E; 25.XII.2019; leg. Freitag; 1 in alcohol; GBIFCH 00515519; ZSM, temporarily stored in AdMU; 1 in alcohol; MT830988; GBIFCH 00763679; PNM • 1 larva; Busuanga, 5 km NW Coron town; Mabintangen R., small mount. riv.; 12°01'45"N, 120°12'19"E; 50 m; 02.II.2020; leg. Freitag; on slide; GBIFCH 00515521; AdMU • 1 larva; 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; on slide; GBIFCH 00592355; ZSM, temporarily stored in AdMU.

Figures

Figure 13. Labiobaetis palawano sp. nov., larva morphology a labrum b right mandible c right prostheca d left mandible e left prostheca f comb-shaped structure at left mola g hypopharynx and superlinguae h maxilla i labium.

Figure 14. Labiobaetis palawano sp. nov., larva morphology a foreleg b fore claw c tergum IV d gill IV e paraproct f antennal scape g metanotum.

Figure 42. Habitus, larvae, dorsal view a Labiobaetis camiguinensis sp. nov. b Labiobaetis lachicae sp. nov. c Labiobaetis palawano sp. nov. d Labiobaetis sabordoi sp. nov.

Figure 47. Habitus, larvae, ventral view a Labiobaetis lachicae sp. nov. b Labiobaetis palawano sp. nov. c Labiobaetis sabordoi sp. nov. d Hypopharynx and superlinguae of Labiobaetis camiguinensis sp. nov.

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