Labiobaetis branchiaesetis, 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 : 39-43

12. Labiobaetis branchiaesetis sp. n. Figures 22, 23, 60a, 65a

Diagnosis.

Larva. Following combination of characters: A) labrum dorsal submarginal arc of setae composed of one plus eight or nine long, simple setae; B) labial palp segment II with a compact, rounded distomedial protuberance; C) fore femur broad, length ca. 2 × maximum width, dorsal margin with a row of ca. 26 curved, spine-like setae and many stout, pointed setae near margin; D) gills margin serrate with small spines intercalating long, fine, simple setae, and with robust, lanceolate setae on margin; E) paraproct surface with scales or scale bases and fine, slightly lanceolate setae as well as fine, simple setae.

Description.

Larva (Figs 22, 23, 60a). Body length 7.5 mm; cerci: 7.5 mm; terminal filament: 3.2 mm; antenna: approximately twice as long as head length.

Colouration. Head, thorax and abdomen dorsally dark brown, abdominal segment X light brown, head and thorax with bright median, dorsal suture. Head, thorax and abdomen ventrally brown, femur dorsal and ventral margins brown, legs otherwise colourless, 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. 22a). Rectangular, length 0.6 × maximum width. Distal margin with medial emargination and a small process. Dorsally with many short to medium, fine, simple setae; submarginal arc of setae composed of one plus 8-9 long, simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid setae; ventral surface with seven short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 22b, c). Incisors fused. Outer and inner sets of denticles with 3 + 3 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. 22d, e). Incisors fused. Outer and inner sets of denticles with 3 + 4 denticles. Prostheca robust, apically denticulate. Margin between prostheca and mola slightly 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. Tuft of setae at apex of mola present.

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

Hypopharynx (Fig. 22f). Lingua about as long as superlingua. Lingua longer than broad; medial tuft of stout setae present; distal half not expanded. Superlingua rounded; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 22g). 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 seven long, simple setae. Maxillary palp 1.2 × as long as length of galea-lacinia; two segmented. Palp segment II 1.5 × length of segment I. Setae on maxillary palp fine and simple, scattered over surface of segments I and II. Apex of last segment rounded, with a slight excavation at inner distolateral margin.

Labium (Fig. 22h). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with nine spine-like setae increasing in length distally; apex with two long and one medium, robust, pectinate setae; outer margin with eight long, spine-like setae increasing in length distally; ventral surface with few short, fine, simple setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, apically pectinate setae; dorsally with one medium, simple seta; ventrally with five 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 compact, rounded distomedial protuberance; distomedial protuberance 0.6 × width of base of segment III; inner and outer margin both with short, fine, simple setae; dorsally with a row of five long, spine-like, simple setae. Segment III conical; apex rounded; length 0.9 × width; ventrally covered with short, fine, simple setae.

Hind wing pads absent.

Foreleg (Fig. 23a, b). Ratio of foreleg segments 1.3:1.0:0.7:0.2. Femur. Length ca. 2 × maximum width. Dorsal margin with a row of ca. 26 curved, spine-like setae and with many stout, pointed setae near margin; length of setae 0.14 × maximum width of femur. Apex rounded; with one curved, spine-like seta and many short, stout, pointed setae. Many stout, lanceolate setae and a few fine, simple setae along ventral margin; femoral patch poorly developed. Tibia. Dorsal margin with a row of short, spine-like setae and many stout, lanceolate setae along margin. Ventral margin with a row of curved, spine-like setae, on apex one bipectinate, spine-like seta and a tuft of long, fine, simple setae. Anterior surface scattered with many stout, lanceolate setae. Tibio-patellar suture present on basal 1/2. Tarsus. Dorsal margin with a row of short, spine-like setae and long, simple setae. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 9-10 denticles; distally pointed; with seven stripes; subapical setae absent.

Tergum (Fig. 23c). Surface with irregular rows of U-shaped scale bases and scattered micropores; scales short, apically rounded. Posterior margin of tergum IV with triangular spines, about as long as wide.

Gills (Fig. 23d, e). Present on segments II - VII. Margin with small denticles intercalating long, fine, simple setae, and with robust, lanceolate setae on margin. Tracheae extending from main trunk to inner margin and partly to outer margin. Gill IV as long as length of segments V and 1/2 VI combined. Gill VII as long as length of segments VIII and 1/3 IX combined.

Paraproct (Fig. 23f). Distally slightly expanded, with many marginal, stout spines. Surface with U-shaped scale bases and scattered fine, slightly lanceolate setae as well as fine, simple setae. Postero-lateral extension (cercotractor) with small marginal spines.

Etymology.

Latin words for gills and seta, refers to the robust, lanceolate setae on the margin of the gills.

Distribution.

New Guinea.

Biological aspects.

The specimens were collected in altitudes of 1000 m a.s.l. and 1700 m– 1800 m a.s.l.

Type-material.

Holotype. Nymph (on slide, GBIFCH 00465183), Papua New Guinea, Eastern Highlands, Marawaka, Ande, 1700-1800 m, 09 Nov 2006, nr 07°01.70'S, 145°49.81'E, Balke & Kinibel (PNG 87). Deposited in ZSM. Paratypes. 24 nymphs (2 on slides, GBIFCH 00465184, GBIFCH 00465185, 14 in alcohol, GBIFCH 00515219, GBIFCH 00508123, deposited in MZL; 8 in alcohol, GBIFCH 00515220, deposited in ZSM), same data as holotype; 3 nymphs (1 on slide, GBIFCH 00465186, 2 in alcohol, GBIFCH 00515286, deposited in MZL), Papua New Guinea, Gulf, Marawaka, nr Ande, 1000 m, 10 Nov 2006, 07°03.60'S, 145°44.38'E, Balke & Kinibel (PNG 89).