Arcobaetis sumbawensis, Kaltenbach & Kluge & Gattolliat, 2023

Kaltenbach, Thomas, Kluge, Nikita J. & Gattolliat, Jean-Luc, 2023, A new, widespread genus of Baetidae from South Asia (Insecta, Ephemeroptera), ZooKeys 1168, pp. 231-266 : 231

publication ID

https://dx.doi.org/10.3897/zookeys.1168.104844

publication LSID

lsid:zoobank.org:pub:28A21391-A433-4E80-8845-E5C0996EFAF0

persistent identifier

https://treatment.plazi.org/id/7A575C67-8D0D-4A93-BB2B-BF7669B229D5

taxon LSID

lsid:zoobank.org:act:7A575C67-8D0D-4A93-BB2B-BF7669B229D5

treatment provided by

ZooKeys by Pensoft

scientific name

Arcobaetis sumbawensis
status

sp. nov.

Arcobaetis sumbawensis sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4 , 5 View Figure 5 , 19 View Figure 19

Type material.

Holotype. Indonesia • male larva (last instar); Sumbawa, Batu Dulang, Mt. Batu Pasak, forest streams; 08°37'42"S, 117°15'27"E, SUMB09; 1380 m; 17.ix.2011; leg. M. Balke; on slide; GBIFCH00975680; MZB. Paratypes. 9 larvae; same data as holotype; 4 on slides; GBIFCH00692615, GBIFCH00975688, GBIFCH00592652, GBIFCH00592653; 5 in alcohol; GenBank OQ699910, OQ699911; GBIFCH00975695, GBIFCH00975689, GBIFCH00975690, GBIFCH00975694; MZL.

Diagnosis.

Larva (Table 1 View Table 1 ). The following combination of characters distinguish A. sumbawensis sp. nov. from other species of Arcobaetis gen. nov.: A) distal margins of segments in middle part of flagellum without enlarged spines; B) labial palp segment III sub-rectangular, at base approx. as wide as distal margin of segment II (Fig. 2h View Figure 2 ); C) hind protoptera absent; D) claw with single row of denticles, four or five distalmost denticles larger, ca. ten basal denticles small to minute (Figs 3b View Figure 3 , 5a View Figure 5 ); E) tergalii present on abdominal segments I-VII; F) posterior margin of tergum IV with triangular spines, slightly wider than long (Fig. 3c View Figure 3 ).

Description.

Larva (Figs 1 View Figure 1 - 5 View Figure 5 ). Body length 5.7-7.0 mm.

Cuticular colouration (Fig. 1a-c View Figure 1 ). Head, thorax, and abdomen dorsally brown, thorax darker. Head, thorax, and abdomen ventrally ochre. Legs ochre, femur distally with brown streak; tibia basally along patella-tibial suture darker. Caudalii ochre.

Hypodermal colouration. Abdomen dorsally with narrow reddish transverse stripes on intersegmental membranes (Fig. 1a View Figure 1 ).

Antenna. Flagellum in middle part without enlarged spines at distal margin of segments.

Labrum (Fig. 2a View Figure 2 ). Length 0.7 × maximum width. Dorsally with sub-median seta, short sub-marginal arc of simple setae, and two setae in between.

Right mandible (Fig. 2b, c View Figure 2 ). Incisor with five denticles; kinetodontium with three denticles.

Left mandible (Fig. 2d, e View Figure 2 ). Incisor with five denticles; kinetodontium with three denticles.

Hypopharynx and superlinguae (Fig. 2f View Figure 2 ). Lingua as long as superlinguae, longer than broad. Superlinguae distally straight; lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 2g View Figure 2 ). Galea-lacinia ventrally with two simple setae just proximad of canines. Medially with one pectinate, spine-like seta and ca. six short to long, simple setae. Maxillary palp approx. 1.5 × as long as galea-lacinia; palp segment II approx. 1.3 × as long as segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II.

Labium (Fig. 2h-j View Figure 2 ). Inner margin of glossa with ca. 16 spine-like setae, increasing in length distally; apex with two long and one medium robust setae; outer margin with ca. 12 spine-like setae; paraglossa ventrally with ca. four medium, simple setae in anteromedial area; dorsally with arc of ca. 10 long, spine-like setae in distal area. Labial palp with segment I 0.7 × length of segments II and III combined. Segment II dorsally with row of ca. four spine-like setae. Segment III sub-rectangular; at base approx. as wide as distal margin of segment II; ventral surface with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera absent.

Legs (Figs 3a, b View Figure 3 , 4a-c View Figure 4 , 5a-c View Figure 5 ). Long and slender, middle, and hind legs slenderer than fore legs. Ratio of leg segments: fore leg 1.3:1.0:0.7:0.2, middle and hind legs 1.2:1.0:0.6:0.1. Femur. Length of fore femur ca. 5 × maximum width, outer and inner margins almost parallel; length of middle and hind femora>6 × maximum width, outer margins slightly concave. Outer margin with row of ca. 12 short, curved, spine-like setae, on fore leg larger than on middle and hind legs. On ventral side with short, spine-like, pectinate, pointed setae; larger and denser on foreleg, smaller and less dense on middle and hind legs. Tibia. Short, stout, pointed, pectinate setae near inner margin. Inner margin with row of short, curved, spine-like, pectinate setae, on apex two longer, curved, spine-like, pectinate setae. Outer margin with one apical, spine-like seta; on fore leg without other spine-like setae, on middle and hind legs with row of few medium, spine-like setae. Patella-tibial suture on proximal ¹/3 of tibia on all legs. Tarsus. Inner margin with row of short, curved, pectinate, spine-like setae; outer margin bare. Claw with one row of denticles; four or five distalmost denticles larger and directed distad; basally ca. 10 small to minute denticles; two vestigial subapical setae on anterior side, one vestigial subapical seta on posterior side (Fig. 5a, b View Figure 5 ).

Abdominal terga (Fig. 3c, d View Figure 3 ). Posterior margin of terga: I smooth, without spines; II-IX with triangular spines, increasing in length toward IX; slightly wider than long on tergum IV; row of spines on tergum IX interrupted by smaller spines in middle part behind bases of submedian setae (similar to Fig. 15j View Figure 15 ). Posterior margin of tergum X with median concavity with smaller spines (similar to Fig. 15k View Figure 15 ).

Abdominal sterna. Posterior margins of sterna: I-V smooth, without spines; VI-IX with triangular spines. On sternum IX of male mature larva row of narrow pointed spines between protogonostyli, smaller spines laterad of protogono-styli and larger, pointed spines laterad of them (similar to Fig. 15m View Figure 15 ).

Tergalii (Fig. 3e View Figure 3 ). Present on abdominal segments I-VII. Tracheation in tergalius I limited to basal part of main trunk. In nine well preserved larvae, only a few tergalii were found, but insertions were always well developed: two tergalii I in one specimen; one tergalius IV and one tergalius V in another specimen, both very small, looking like replacements of naturally broken tergalii.

Paraproct (Fig. 3f View Figure 3 ). Posterior margin with ca. 16 stout spines. Surface scattered with scale bases and micropores.

Caudalii. Cerci and paracercus with broad triangular spines on posterior margin of each segment.

Etymology.

The specific epithet refers to the type locality in Sumbawa (Indonesia).

Distribution.

Indonesia: Sumbawa (Fig. 19 View Figure 19 ).

Biological aspects.

The species was found at an altitude of 1380 m.