Labiobaetis paraoperosus, 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

21. Labiobaetis paraoperosus sp. nov. Figures 36 , 37 , 51d , 55b

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of 1 + 9 or 10 long, feathered setae; B) labial palp segment II with a large, thumb-like distomedial protuberance, segment III oblong; C) fore femur rather broad, length ca. 4 × maximum width, dorsal margin with a row of 11-18 spine-like setae; D) hindwing pad well developed; E) paraproct distally not expanded, with ca. 30 stout marginal spines.

Description.

Larva ( Figs 36 , 37 , 51d ). Body length 5.5-6.0 mm; antenna approximately 3 × as long as head length; cerci ca. 0.7 × body length.

Colouration. Head, thorax, and abdomen dorsally brown, head and thorax with bright median, dorsal suture, thorax and abdomen with pattern as in Fig. 51d . Forewing pads light brown at base and with light brown distal spots. Head, thorax, and abdomen ventrally very light brown, abdominal segments VIII and IX brown. Legs transparent, femur with a distomedial, brown spot and brown apex, caudal filaments transparent with a dark brown band at ca. 1/3 of cerci.

Antenna with scape and pedicel subcylindrical, with well-developed distolateral process at scape; flagellum with lanceolate spines and fine, simple setae on apex of each segment.

Labrum ( Fig. 36a ). Rectangular, length 0.7 × maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae; submarginal arc of setae composed of 1 + 9 or10 long, feathered setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with three short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Fig. 36b, 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 straight. Tuft of setae at apex of mola present.

Left mandible ( Fig. 36d, e ). Incisors fused. Outer and inner sets of denticles with 4 + 3 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 present.

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

Hypopharynx ( Fig. 36f ). Lingua approx. as long as superlingua. Lingua broader than long; medial tuft of stout setae poorly developed; distal half not expanded. Superlingua rounded; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla ( Fig. 36g ). 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 4-5 long, 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. 36h, i ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with eight or nine spine-like setae increasing in length distally; apex with two long and one medium, robust, pectinate setae and one short, robust seta; outer margin with 5-7 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 two or three medium, simple setae in anteromedial area and partly one short, simple seta in proximomedial area; dorsally with a row of four or five 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 broad thumb-like distomedial protuberance; distomedial protuberance 0.9 × width of base at segment III; inner and outer margin with short, fine, simple setae; dorsally with two long, spine-like, simple setae near outer margin. Segment III oblong; apex rounded; length 1.5 × width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind wing pads well developed.

Foreleg ( Fig. 37a, b ). Ratio of foreleg segments 1.2:1.0:0.5:0.2. Femur. Length ca. 4 × maximum width. Dorsal margin with a row of 11-18 spine-like setae and one or two spine-like setae near margin; length of setae 0.25 × maximum width of femur. Apex rounded; with one pair of curved, spine-like setae and some short, stout setae. Many short, stout, lanceolate setae scattered along the ventral margin; femoral patch absent. Tibia. Dorsal margin with a row of short, stout setae; on apex one longer seta, and a row of short, stout setae close to dorsal margin. Ventral margin with a row of curved, spine-like setae, distally longer, on apex one bipectinate, spine-like seta and a tuft of long, fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Patellotibial suture present on basal 1/2. Tarsus. Dorsal margin with a row of short, stout setae and long, fine, simple setae. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 9-11 denticles; distally pointed; with 3-5 stripes; subapical setae absent.

Tergum ( Fig. 37c ). 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. 37d ). 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 1/3 VI combined. Gill VII as long as length of segment VIII.

Paraproct ( Fig. 37e ). Distally not expanded with 29-32 stout marginal spines. Surface scattered with U-shaped scale bases and fine, simple setae. Cercotractor with numerous small marginal spines.

Etymology.

Refers to the morphological similarity with L. operosus .

Distribution.

Indonesia: Sumatra.

Biological aspects.

The specimens were collected at altitudes between sea level and 890 m, one of them in a small (2 m wide), shallow (25 cm deep) and slow (velocity 0.3 m/s) stream in a highly disturbed area (agriculture, livestock, waste). The substrate was predominantly stone and gravel without patches of leaf litter or dead wood.

Type-material.

Holotype. Larva (on slide, GBIFCH 00592254), Indonesia, Sumatra, Aceh, Ketambe, Alas River at Cinta Alam Lodge, 03°40.73'N, 97°39.37'E, 400 m, 14.X.2013, M. Balke leg. (SUM 45). Temporary deposited in MZL before definitely housed in MZB. Paratypes. 11 larvae (1 on slide, GBIFCH 00592253, 5 in alcohol, GBIFCH 00515329, GBIFCH 00515338, deposited in MZL; 5 in alcohol, GBIFCH 00515328, deposited in ZSM), same data as holotype; 1 larva (on slide, GBIFCH 00592249, deposited in MZL), Indonesia, Sumatra Barat, Sawahlunto, stream, 275 m, 10.XI.2011, 00°41.33'S, 100°46.72'E, M. Balke leg. (UN5); 1 larva (on slide, GBIFCH 00422165, deposited in MZL), Indonesia, Sumatra, volcano Marapi, 00°21.97'S, 100°33.30'E, 890 m, 02.IV.2014, M. Gueuning leg.; 2 larvae (on slides, GBIFCH 00592248, GBIFCH 00592247, deposited in MZL), Indonesia, Sumatra Barat, Tarusan, upstream Tarusan, 01°13.62'S, 100°29.83E, 10 m, 24.V.2010, J.-M. Elouard leg.

Figures

Figure 36. Labiobaetis paraoperosus 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 37. Labiobaetis paraoperosus sp. nov., larva morphology: a Foreleg b Fore claw c Tergum IV d Gill IV e Paraproct f Scape g Metanotum.

Figure 51. Habitus, larvae, dorsal view: a Labiobaetis multus b Labiobaetis jonasi sp. nov. c Labiobaetis jonasi sp. nov. d Labiobaetis paraoperosus sp. nov.

Figure 55. Distribution of Labiobaetis in Indonesia.