Baetis procul, Kaltenbach, 2025

Kaltenbach, Thomas, 2025, Mayflies of the Fiji Islands (Ephemeroptera), ZooKeys 1259, pp. 205-276 : 205-276

publication ID	https://doi.org/10.3897/zookeys.1259.168521
publication LSID	lsid:zoobank.org:pub:48F9008F-BC5F-49BA-994A-2142AF2EAE55
DOI	https://doi.org/10.5281/zenodo.17583246
persistent identifier	https://treatment.plazi.org/id/6019203B-2827-5126-925C-7B3160E21525
treatment provided by	ZooKeys by Pensoft
scientific name	Baetis procul
status	sp. nov.

Treatment

Baetis procul sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Material examined.

Holotype. FIJI • larva; Viti Levu , Ba Prov., Sabeto Riv., near Sabeto; 17 ° 43 ' 09 " S, 177 ° 31 ' 21 " E; 30 m; 17. xi. 2024; leg. T. Kaltenbach; on slides; GBIFCH 01221812, GBIFCH 01221813; MZL GoogleMaps . Paratypes. • 11 larvae; same data as holotype; 2 on slides; GBIFCH 01221839, GBIFCH 01581967, GBIFCH 01581968; 9 in alcohol; GBIFCH 01581966, GBIFCH 01581969, GBIFCH 01581970; MZL GoogleMaps • 3 female imagos; Viti Levu , Ba Prov., Ba Riv., near Outback Hotel; 17 ° 37 ' 35 " S, 177 ° 45 ' 04 " E; 20 m; 22. x. 2024; leg. T. Kaltenbach; 1 on slide; GBIFCH 01221835; 2 in alcohol; GBIFCH 01581964, GBIFCH 01581965; MZL GoogleMaps .

Diagnosis.

Larva. Following combination of characters differentiate Baetis procul sp. nov. from other species of Baetis , some of the characters also from the most similar species Baetis taiwanensis Müller-Liebenau, 1985 : tergalii present on abdominal segments I – VII; hind protopteron developed; abdominal terga I – VIII grey-brown, with distinct sublateral pale areas; femur with yellowish to yellow-brown, subapical spot on anterior side.

Description.

Larva (Figs 1 View Figure 1 – 3 View Figure 3 ). Body length 3.1–4.0 mm. Cerci ~ ½ body length; paracercus ~ ⅓ of body length. Antenna: ~ 2 × head length.

Colouration (Figs 1 a – d View Figure 1 , 3 a, i View Figure 3 ). Head and thorax dorsally grey with indistinct yellowish grey pattern as in Fig. 1 a, c View Figure 1 . Abdominal terga I – VIII dorsally grey-brown, with distinct sublateral, yellowish grey markings; terga IX and X yellowish grey. Fore protoptera grey. Thorax and abdomen ventrally pale yellowish grey, laterally with grey streaks. Legs off-white, femur distomedially with grey marking, tibia and tarsus distally darker. Caudalii off-white, with dark brown section in middle part, cerci with additional dark brown section subdistally.

Labrum (Fig. 2 a, b View Figure 2 ). Sub-rectangular, length 0.6 × maximum width. Distal margin with medial emargination and small process. Dorsally with pair of submedian setae, and submarginal arc of three or four medium to long, simple setae on each side. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid, feathered setae.

Right mandible (Fig. 2 f View Figure 2 ). Incisor and kinetodontium fused. Incisor with five denticles; kinetodontium with three denticles. Prostheca robust, apically denticulate. Margin between prostheca and mola slightly convex, smooth. Tuft of setae on proximal corner of mola present.

Left mandible (Fig. 2 e View Figure 2 ). Incisor and kinetodontium fused. Incisor with four denticles, kinetodontium with three denticles. Prostheca robust, apicolaterally with small denticles and comb-shaped structure. Margin between prostheca and mola almost straight, with few minute denticles. Tuft of setae on proximal corner of mola absent.

Both mandibles with lateral margins almost straight.

Hypopharynx and superlinguae (Fig. 2 d View Figure 2 ). Lingua approx. as long as superlinguae. Lingua longer than broad; medial tuft of stout setae poorly developed, short. Superlinguae with lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 2 g View Figure 2 ). Galea-lacinia ventrally with two simple, apical setae below canines. Medially with one feathered, spine-like seta and three short to long, simple setae. Maxillary palp slightly longer than length of galea-lacinia; 2 - segmented; palp segment II ~ 1.1 × as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of segment II slightly pointed.

Labium (Fig. 2 c View Figure 2 ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ~ 7 spine-like seta; apex with three long robust setae; outer margin with ~ 3 spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa sub-rectangular, slightly curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and two short, simple setae in anteromedial area; dorsally with four long, spine-like setae near inner margin. Labial palp with segment I approx. as long as length of segments II and III combined. Segment II without developed distomedial protuberance; dorsally with two or three spine-like setae near outer margin. Segment III nearly semicircular; length ~ 0.8 × maximal width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera (Fig. 2 i View Figure 2 ) present, well developed.

Legs (Fig. 3 a – h View Figure 3 ). Ratio of foreleg segments 1.5: 1.0: 0.8: 0.3, middle leg 1.6: 1.0: 0.8: 0.4, hind leg 1.5: 1.0: 0.7: 0.3. Femur. Femur length ~ 3 × maximum width. Outer margin with a row of 9–17 spine-like setae; length of setae ~ 0.3 × maximum width of femur. Apex rounded, with pair of spine-like setae and short, stout, apically blunt setae. Stout, lanceolate, pointed setae scattered along inner margin; femoral patch well developed on all legs. Tibia. Outer margin with row of short, stout, pointed setae. Inner margin with spaced row of short, spine-like setae, on apex tuft of fine, simple setae. Patella-tibial suture present on basal ¾. Tarsus. Outer margin with spaced row of short, stout, pointed setae. Inner margin with row of curved, spine-like setae increasing in length distally. Claw with one row of 13–15 denticles; distally pointed.

Abdominal terga (Fig. 3 i, j View Figure 3 ). Surface with irregular rows of U-shaped scale bases. Posterior margin of terga: I – VIII with small, short, rounded, transparent spines; IX with longer, acute, triangular, spines.

Abdominal sterna (Fig. 3 j View Figure 3 ). Posterior margin of sterna: I – VIII smooth, without spines; IX laterally with small, triangular spines.

Tergalii (Fig. 3 k, l View Figure 3 ). Present on segments I – VII. Skew oval in shape, margin with small denticles intercalating fine, simple setae. Tergalius I as long as length of segment II; tergalius IV as long as segments V and VI combined; tergalius VII slightly longer than segment VIII.

Paraproct (Fig. 3 m View Figure 3 ). Distally not expanded, with five or six stout, marginal spines. Cercotractor with numerous small, marginal spines.

Imago. Male. Unknown.

Diagnosis.

Imago, female. Following characters differentiate Baetis procul sp. nov. from Baetis taiwanensis Müller-Liebenau, 1985 ( Fujitani et al. 2004: figs 3, 6): hindwing narrower, with anal margin concave; costal process more developed.

Description.

Imago, female (Fig. 4 a – f View Figure 4 ). Body length ~ 3.2 mm, fore wing length ~ 3.9 mm, hind wing length ~ 0.5 mm. Head and antennae dark brown. Thorax and abdomen grey-brown. Fore wing with membrane colourless, base of wings slightly brownish; veins brown, covered with very fine setae; pterostigma with four oblique crossveins, mostly nearly complete. Hind wing very small, narrow, anal margin concave; with two nearly parallel, longitudinal veins; costal margin with distinct process in basal ½; veins grey-brown, covered with very fine setae similar to fore wing. Legs grey-brown; femur anteriorly with diffuse reddish brown colour, more developed on foreleg.

Biological aspects.

Living in the run of medium fast flowing lowland rivers in algae on stones (Figs 36 c View Figure 36 , 37 b View Figure 37 ). Female imagos are laying their eggs under water, probably in algae. When caught by kick-sampling, larvae are always swimming very fast and straight to the next algae or debris to cling on.

Etymology.

The name procul, meaning “ far away ” or “ at a distance ” in Latin, refers to the large geographic distance of this new species to other known Baetis species (see discussion).

Distribution.

Fiji, Viti Levu (Fig. 39 a View Figure 39 ).