Labiobaetis lobatus, Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2018

Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2018, The incredible diversity of Labiobaetis Novikova & Kluge in New Guinea revealed by integrative taxonomy (Ephemeroptera, Baetidae), ZooKeys 804, pp. 1-136 : 8-11

2. Labiobaetis lobatus sp. n. Figures 4, 5, 58b, 64a

Diagnosis.

Larva. Following combination of characters: A) labrum dorsal, submarginal arc of setae composed of 15 spatulate, apically pectinate setae; B) labial palp segment II with a large, lobed distomedial protuberance; C) fore femur length ca. 4 × maximum width, dorsal margin with a row of ca. 16 curved, spine-like setae and a few spine-like setae near margin; D) fore claw with a row of 13-14 denticles; E) paraproct distally expanded.

Description.

Larva (Figs 4, 5, 58b). Body length 5.3 mm; antenna: approximately 2.5 × as long as head length.

Colouration. Head, thorax and abdomen dorsally brown, thorax with bright, faint pattern as in Fig. 58b. Head and thorax with brighter median, dorsal suture, forewing pads with bright striation. Head, thorax and abdomen ventrally light brown, legs and caudal filaments light brown.

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

Labrum (Fig. 4a, 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 15 long, spatulate, apically pectinate setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid setae; ventral surface with eight short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 4c, d). Incisors fused. Outer and inner sets of denticles with 4 + 4 denticles. Inner margin of innermost denticle with 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. 4e, f). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles. Prostheca robust, apically with small denticles and comb-shape 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. 4g). Lingua about as long as superlingua. Lingua longer than broad; medial tuft of stout setae present; distal half not expanded. Superlingua straight; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 4h). 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 six long, simple setae. Maxillary palp 1.5 × as long as length of galea-lacinia; two segmented. Palp segment II about as long as segment I. Surface of maxillary palp scattered with fine and simple setae. Apex of last segment rounded, with excavation at inner distolateral margin.

Labium (Fig. 4i). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with nine spine-like setae increasing in length distally; apex with two long, robust, pectinate setae, one medium and one short, robust seta; outer margin with six long spine-like setae increasing in length distally; ventral surface with fine, simple setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, apically pectinate setae; dorsally with 4-5 medium, simple setae; ventrally with three long, spine-like setae near inner margin. Labial palp with segment I 0.7 × length of segments II and III combined. Segment I covered with short, fine, simple setae ventrally and micropores dorsally. Segment II with a large, lobed distomedial protuberance; distomedial protuberance 0.9 × width of base at segment III; inner and outer margin both with short, fine, simple setae; dorsally with two long, spine-like, simple setae. Segment III slightly pentagonal; apex slightly pointed; length 1.2 × width; ventrally covered with medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg (Fig. 5a, b). Ratio of foreleg segments 1.2:1.0:0.5:0.2. Femur. Length ca. 3.5 × maximum width. Dorsal margin with a row of ca. 16 curved, spine-like setae and a few stout, pointed setae near margin; length of setae 0.18 × maximum width of femur. Apex rounded; with one pair of curved, spine-like setae and some short, stout, apically rounded setae. Many stout, lanceolate setae and a few fine, simple setae scattered along the ventral margin; femoral patch poorly developed. Tibia. Dorsal margin with a row of short, curved, spine-like setae. Ventral margin with a row of curved, spine-like setae and some bipectinate, spine-like setae on apex. Anterior surface scattered with stout, lanceolate setae. Tibio-patellar suture present on basal 1/2. Tarsus. Dorsal margin almost bare. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 13-14 denticles; distally pointed; with six stripes; subapical setae absent.

Tergum (Fig. 5c). Surface scattered with U-shaped scale bases and micropores. Posterior margin of tergum IV with triangular spines, wider than long.

Gills (Fig. 5d). 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 2/3 VI combined. Gill VII as long as length of segments VIII and 2/3 IX combined.

Paraproct (Fig. 5e). Distally expanded, with many marginal, stout spines. Surface with U-shaped scale bases and scattered fine, simple setae and micropores. Postero-lateral extension (cercotractor) with small marginal spines.

Etymology.

Refers to the large, lobed, distomedial protuberance of labial palp segment II.

Distribution.

New Guinea.

Biological aspects.

The specimens were collected at an altitude of 1390 m a.s.l.

Type-material.

Holotype. Nymph (on slide, GBIFCH 00508141), Papua New Guinea, Central, Kokoda Trek, 1390 m, Jan 2008, 09°00.34'S, 147°44.25'E, Posman (PNG 173). Deposited in ZSM. Paratypes. 34 nymphs (2 on slides, GBIFCH 00465161, GBIFCH 00465162, 20 in alcohol, GBIFCH 00515232, deposited in MZL; 12 in alcohol, GBIFCH 00515233, deposited in ZSM), same data as holotype.