Protobehningia merga Peters & Gillies, 1991

Kwanboon, Sedtawut, Sartori, Michel & Boonsoong, Boonsatien, 2021, Behningiidae and Potamanthidae (Insecta, Ephemeroptera) in Thailand, ZooKeys 1067, pp. 57-82 : 57

publication ID	https://dx.doi.org/10.3897/zookeys.1067.72779
publication LSID	lsid:zoobank.org:pub:8DB9C8FE-9DF7-438D-92BA-4B40E81F5DE1
persistent identifier	https://treatment.plazi.org/id/E47AD7D9-ECE5-56F7-863F-E00403810630
treatment provided by	ZooKeys by Pensoft
scientific name	Protobehningia merga Peters & Gillies, 1991
status

Treatment

Figures 1B View Figure 1 , 5 View Figure 5 , 6 View Figure 6 , 8 View Figure 8 , 9 View Figure 9

Materials examined.

2 larvae, deposited in ZMKU, Thailand, Chiang Mai province, Mae Chaem district, Mae Chaem river , 18°30'46.0"N 98°21'22.6"E, 475 m, 5.X.2019, B. Boonsoong leg. GoogleMaps , 1 larva, same data, 13.XI.2020, B. Boonsoong leg. GoogleMaps (ZMKU).

Re-description of larva.

Larva (in alcohol, Fig. 1B View Figure 1 ) Body length 7.2 mm without cerci; cerci 2.7 mm. Body pale yellowish.

Head. Anterior margin not projecting, front with densely short goldish setae standing out on the head (Fig. 1B View Figure 1 , 5A View Figure 5 ). Black eyes on dorsolateral margin; ocelli almost white, inner margin of ocelli black in front of compound eye. Antennae at lateral margin of head. Labium extending the entire anterior margin of head, with long setae; labial palp 3-segmented, surface of labial palp covered with rows of long blunt setae, base of second palp segment with the longest setae, first segment longer than other segments (Fig. 5B View Figure 5 ), glossae and paraglossae with numerous (>20) setae (Fig. 5C View Figure 5 ). Left mandible and right mandible strong and dentated, mostly similar to P. asiatica . Maxillary palpi 3-segmented, maxilla base extending, apex narrow with terminal tooth.

Thorax. Colour pale yellowish. Forelegs flattened, with large broad coxae, flat femur, small claws (Fig. 6A View Figure 6 ), tarsi fused with tibiae (Fig. 6B View Figure 6 ), outer margin with long row of setae, short setae present at inner margin. Midleg and hindleg tarsus and tibia not fused (Fig. 6C, D View Figure 6 ), hindleg with strong claw, curved, thorn-like in shape.

Abdomen. Similar in colour to head and thorax, abdominal segments elongated and convex, with short straight setae at lateral margin, lateral margin of abdominal segment I-IX with flat projections spine-like in shape. Gill present on segment I-VII, plumose shape, first gill filament single (Fig. 5D View Figure 5 ); gills II-VII double, upper branch of each gill shorter than lower one. Three caudal filaments fringed with short pale setae, length of median filament as long as lateral filaments.

Diagnosis.

The larvae of Protobehningia merga Peters & Gillies 1991 can be distinguished from those of P. asiatica based on the following characteristics: i) glossae and paraglossae with more than 20 setae on the ventral surface, ii) maxillary palp segment II 2/3 the length of segment I, each maxillary palp segment completely divided, but segments II and III indistinct ( Peters and Gillies 1991).

Distribution.

Kanchanaburi and Chiang Mai provinces.

Biological aspects.

In general, the larvae of behningiid mayflies are rarely collected. In this study, the larvae (middle instar) were found in October (turbidity from flooding, Fig. 8A View Figure 8 ) and November in a river in Chaing Mai province, whereas Peters and Gillies (1991) found the exuviae and imago during December in Kanchanaburi province (western Thailand). The specimens were collected from the Mae Chaem river, which is submontane and bordered by farmland and residential areas (Fig. 8A View Figure 8 ). The substrates were covered with fine- and coarse-grained sand (Fig. 8C View Figure 8 ). The larvae of P. merga were collected using an aquatic net in a fine sandy habitat, where the depth of the sandy bottom was more than 50 cm and near the littoral zone (Fig. 8B, D View Figure 8 ). The larvae were usually found together with those of the oligoneuriid mayfly, Chromarcys magnifica Navás, 1932 and the gomphid dragonfly, Paragomphus capricornis Förster, 1914.

Remarks.

Only two species of Protobehningia are known in the world: Protobehningia asiatica Tshernova & Bajkova 1960 and Protobehningia merga Peters & Gillies 1991. Peters and Gillies (1991) used larval exuviae of P. merga for comparison with P. asiatica , but they did not give a more detailed description of the larval stage. The labium structures of our specimens are similar to those of the larval exuviae described by Peters and Gillies (1991). Our new record also expands the geographic distribution of P. merga to northern Thailand.