Nigrobaetis borneus, Kaltenbach & Gattolliat, 2023

Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2023, New species of Nigrobaetis from Southeast Asia (Ephemeroptera, Baetidae), ZooKeys 1166, pp. 175-234 : 175

publication ID	https://dx.doi.org/10.3897/zookeys.1166.102941
publication LSID	lsid:zoobank.org:pub:29BC14B3-2F38-429C-B0E1-F877D1FE5A15
persistent identifier	https://treatment.plazi.org/id/C934D238-B803-4B19-897C-C35BE989726E
taxon LSID	lsid:zoobank.org:act:C934D238-B803-4B19-897C-C35BE989726E
treatment provided by	ZooKeys by Pensoft
scientific name	Nigrobaetis borneus
status	sp. nov.

Treatment

Nigrobaetis borneus sp. nov.

Figs 28 View Figure 28 , 29 View Figure 29 , 30 View Figure 30 , 31 View Figure 31 , 32 View Figure 32 , 33 View Figure 33 , 40c View Figure 40

Differential diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submedian seta and two long, simple setae in submarginal position; length 0.8 × width (Fig. 29a-c View Figure 29 ); B) right mandible: incisor with five denticles, kinetodontium with three denticles (Fig. 29d View Figure 29 ); C) left mandible: incisor with four denticles, kinetodontium with four denticles; margin between prostheca and mola straight, with row of few short, setae-like processes (Fig. 29e View Figure 29 ); D) fore femur length ca. 2.4 × maximum width, dorsal margin with 7-9 curved, spine-like setae (Fig. 32a View Figure 32 ); E) tibia dorsally bare, distally with one stout, apically rounded seta (Fig. 32a, c View Figure 32 ); F) claw with 12-14 denticles (Fig. 32d View Figure 32 ); G) hind protoptera absent; H) tergalii on abdominal segments I-VII; I) posterior margins of abdominal terga: I smooth, without spines; II-IX with triangular, pointed spines (Fig. 33 View Figure 33 ).

Description.

Larva (Figs 28 View Figure 28 - 33 View Figure 33 ). Body length 3.0-3.3 mm. Caudalii broken. Antennae ca. 2.5 × head length.

Colouration (Fig. 28a-c View Figure 28 ). Head dorsally pale brown, thorax, and abdomen dorsally brown, with bright pattern as Fig. 28c View Figure 28 . Head, thorax, and abdomen ventrally pale brown. Legs pale brown, femur apically brown and with a brown, distomedial spot. Caudalii brown.

Labrum (Fig. 29a-c View Figure 29 ). Length 0.8 × maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submedian seta and two long, simple, submarginal setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid, pectinate setae.

Right mandible (Fig. 29d View Figure 29 ). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with five denticles, inner margin of innermost denticle without row of thin setae. Prostheca stick-like, apicolaterally denticulate. Margin between prostheca and mola straight, with row of setae-like processes. Tuft of setae at apex of mola present.

Left mandible (Fig. 29e View Figure 29 ). Incisor and kinetodontium fused. Incisor with four denticles; kinetodontium with four denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with row of few short, setae-like processes. Tuft of setae at apex of mola absent.

Hypopharynx and superlinguae (Fig. 30a View Figure 30 ). Lingua shorter than Hypopharynx superlinguae . Lingua longer than broad; medial tuft of stout setae poorly developed; distal half laterally not expanded. Superlinguae distally rounded; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 30b-d View Figure 30 ). Galea-lacinia ventrally with two simple, apical setae under canines. Medially with one spine-like seta and ca. four long, simple setae. Maxillary palp ca. 1.2 × as long as length of galea-lacinia; 2-segmented; palp segment II ca. 1.3 × as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment slightly pointed.

Labium (Fig. 31a-f View Figure 31 ). Glossa basally broad, narrowing toward apex; approx. as long as paraglossa; inner margin with ca. eight spine-like setae; apex with two long and one medium, robust setae; outer margin with ca. six spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and ca. two medium, simple setae in anteromedial area; dorsally with three long, spine-like, simple setae near inner margin. Labial palp with segment I 0.9 × length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II without protuberance; ventral surface with short, fine, simple setae; dorsally with row of ca. three long, spine-like setae. Segment III slightly pentagonal; length subequal to maximum width; inner apical margin with some setae-like processes (Fig. 31f View Figure 31 ); ventrally with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera: Absent.

Foreleg (Fig. 32a-d View Figure 32 ). Ratio of foreleg segments 1.2:1.0:0.9:0.3. Femur. Length ca. 2.4 × maximum width. Dorsal margin with 7-9 curved, spine-like setae; length of setae 0.27 × maximum width of femur. Apex rounded, with pair of spine-like setae. Medium, stout, lanceolate setae along ventral margin; femoral patch absent. Tibia. Dorsal margin bare, on apex one stout, apically rounded seta. Ventral margin with row of short to medium curved, spine-like setae, on apex two longer, spine-like, pectinate setae. Anterior surface with few stout, lanceolate setae along ventral margin. Patellatibial suture present on basal half. Tarsus. Dorsal margin bare. Ventral margin with row of curved, spine-like setae. Claw with one row of 12-14 denticles; distally pointed; subapical setae absent.

Middle and hind legs. As foreleg.

Abdominal terga (Fig. 33 View Figure 33 ). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I smooth, without spines; II-IX with triangular, pointed spines.

Abdominal sterna. Posterior margin of sterna smooth, without spines.

Tergalii (Fig. 32e View Figure 32 ). Present on segments I-VII. Margin with small denticles intercalating fine simple setae. Tracheae restricted to main trunk and few branches, not reaching margins. Tergalius I as long as length of segment II; Tergalius IV as long as length of segments V and 1/2 VI combined; Tergalius VII as long as segments VIII and 1/2 IX combined.

Paraproct. With six or seven stout, marginal spines. Surface scattered with U-shaped scale bases, fine, simple setae, and micropores. Cercotractor with numerous small, marginal spines.

Adult stages. Unknown.

Etymology.

Referring to the island of Borneo, where the species was collected.

Distribution

(Fig. 40c View Figure 40 ). Indonesia, Borneo (East Kalimantan).

Biological aspects.

The specimens were collected at an altitude of 160 m in a large (width ca. 36 m), shallow (depth ca. 0.1 m), fast flowing (ca. 0.9 m/s) stream. The stream was characterised by equally run/riffles and pools. Water temperature was 25 °C, substrate was dominated by boulder and cobble.

Type-material.

Holotype. Indonesia • larva; East Kalimantan, Bas. Malinau, riv. Seturan, loc. Seturan (2001-block 57), trib. Bengahau; 02°59'22"N, 116°30'46"E; 08.viii.2000; leg. P. Derleth; on slide; GBIFCH00592663; MZL. Paratypes. Indonesia • 3 larvae; same data as holotype; 1 on slide; GBIFCH00975692; 2 in alcohol; GBIFCH00975674; MZL.