Labiobaetis pakpak, Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2019

Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2019, The tremendous diversity of Labiobaetis Novikova & Kluge in Indonesia (Ephemeroptera, Baetidae), ZooKeys 895, pp. 1-117 : 1

12. Labiobaetis pakpak sp. nov. Figures 20 , 21 , 48d , 55a

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of 18-19 clavate setae; B) labial palp segment II with large, lobed distomedial protuberance, segment III slightly pentagonal; C) left mandible without setae at apex of mola; D) fore femur rather slender, length ca. 4 × maximum width, dorsal margin with a row of 12-15 spine-like setae and many fine, simple setae; E) paraproct distally expanded, with> 40 stout marginal spines.

Description.

Larva ( Figs 20 , 21 , 48d ). Body length 3.7 mm.

Colouration. Head, thorax, and abdomen dorsally brown, head and thorax with bright median, dorsal suture. Head, thorax, and abdomen ventrally light brown, legs transparent, caudal filaments light brown.

Antenna with scape and pedicel subcylindrical, without distolateral process at scape; flagellum with lanceolate spines and fine, simple setae on apex of each segment.

Labrum ( Fig. 20a ). Rectangular, length 0.7 × maximum width. Distal margin with medial emargination and a small process. Dorsally with long, fine, simple setae scattered over surface; submarginal arc of setae composed of 18-19 long, clavate setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid setae; ventral surface with five short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Fig. 20b, c ). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles and one minute intermediate denticle. 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. 20d, e ). Incisors fused. Outer and inner sets of denticles with 3 + 3 denticles and one minute intermediate denticle. 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 ( Fig. 20f ). Lingua approx. as long as superlingua. Lingua longer than broad; medial tuft of stout setae well developed; distal half laterally expanded. Superlingua straight; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla ( Fig. 20g ). Galea-lacinia with two simple, robust apical setae under crown. 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 3-4 medium, simple setae. Maxillary palp 1.4 × as long as length of galea-lacinia; two 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 slight excavation at inner distolateral margin.

Labium ( Fig. 20h, i ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with 4-6 spine-like setae increasing in length distally; apex with two long and one medium, robust setae; outer margin with 4-6 long, spine-like setae increasing in length distally; 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 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 large, lobed distomedial protuberance; distomedial protuberance 0.8 × width of base of segment III; inner and outer margin with short, fine, simple setae; dorsally with two long, spine-like, simple setae near outer margin. Segment III slightly pentagonal; apex slightly truncate; length 1.2 × width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg ( Fig. 21a, b ). Ratio of foreleg segments 1.3:1.0:0.5:0.2. Femur. Length ca. 4 × maximum width. Dorsal margin with a row 12-15 spine-like setae and many fine, simple setae; length of setae 0.23 × maximum width of femur. Apex rounded; with 1-2 pairs of curved, spine-like setae and some short, stout setae. Many stout, lanceolate setae scattered along the ventral margin; femoral patch poorly developed. Tibia. Dorsal margin with a row of short, stout setae (not always present) and fine, simple setae. Ventral margin with a row of short, spine-like setae, on apex some stout, spine-like, partially bipectinate setae and a tuft of fine, simple 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. Tarsal claw with one row of 10-11 denticles; distally pointed; with three stripes; subapical setae absent.

Tergum ( Fig. 21c ). Surface with rows of U-shaped scale bases and scattered micropores. Posterior margin of tergum IV with triangular spines, wider than long.

Gills ( Fig. 21d ). 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 1/2 IX combined.

Paraproct ( Fig. 21e ). Distally expanded, with> 40 stout marginal spines. Surface scattered with U-shaped scale bases and micropores. Cercotractor with numerous small marginal spines.

Etymology.

Dedicated to the indigenous Pakpak people from Sumatra.

Distribution.

Indonesia: Sumatra.

Biological aspects.

The specimens were collected in forest at an altitude of 490 m.

Type-material.

Holotype. Larva (on slide, GBIFCH 00592219), Indonesia, Sumatra Barat, Sijunjung / Muara area, forest, 488 m, 10.XI.2011, 00°40.10'S, 101°07.26'E, M. Balke leg. (UN7). Temporary deposited in MZL before definitely housed in MZB. Paratypes. 10 larvae (2 on slides, GBIFCH 00592221, GBIFCH 00592220, 3 in alcohol, GBIFCH 00235851, GBIFCH 00235781, GBIFCH 00515344, deposited in MZL; 5 in alcohol, GBIFCH 00515345, deposited in ZSM), same data as holotype.

Figures

Figure 20. Labiobaetis pakpak sp. nov., larva morphology: a Labrum b Right mandible c Right prostheca d Left mandible e Left prostheca f Hypopharynx g Maxilla h Labium i Apex of paraglossa.

Figure 21. Labiobaetis pakpak sp. nov., larva morphology: a Foreleg b Fore claw c Tergum IV d Gill IV e Paraproct f Scape.

Figure 48. Habitus, larvae, dorsal view: a Labiobaetis weifangae sp. nov. b Labiobaetis itineris sp. nov., without head c Labiobaetis lubu sp. nov. d Labiobaetis pakpak sp. nov.

Figure 55. Distribution of Labiobaetis in Indonesia.