Synorthocladius bifidus Liu & Wang, 2005

Wang, Rui-Hao, Zhang, Zhi-Chao, Feng, Hui-Yuan & Lin, Xiao-Long, 2025, Larval morphology and DNA barcode of Synorthocladius bifidus Liu & Wang, 2005 (Diptera: Chironomidae), Zootaxa 5660 (1), pp. 139-146 : 140-144

publication ID	https://doi.org/10.11646/zootaxa.5660.1.11
persistent identifier	https://treatment.plazi.org/id/DD7987CE-FF88-FFC2-7991-F8EA993EDAD3
treatment provided by	Plazi
scientific name	Synorthocladius bifidus Liu & Wang, 2005
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Treatment

Synorthocladius bifidus Liu & Wang, 2005 View in CoL

( Figs 2–4 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Examined material. 3 larvae ( SHOU & BOLD sample ID: ZJ733, ZJ735, ZJ739), China, Zhejiang, Wenzhou, Yueqing , Lingdi County, Hushangyang Village , 28.304°N, 120.93°E, 570 m a.s.l., D-net, 11.XI.2019, leg. Xiao-Long Lin GoogleMaps ; 1 larva

( SHOU & BOLD sample ID: ZJ919), China, Zhejiang, Wenzhou, Yueqing, Furong Zhen , Benjue Temple , 28.2999°N, 120.991°E, 64 m a.s.l., D-net, 30.III.2019, leg. Xiao-Long Lin. GoogleMaps

Diagnostic characters. Antenna with 4 or apparently 5 segments; third segment long, second segment apically broadened. Blade and style long.AR 1.27–1.45. Premandible simple with a broad inner tooth. Ventromental plate extended, cardinal beard long, with simple branches radiating from a common area. A strong spine is situated on the inner margin of the mandible. Premandible length 50−60 μm, a protuberance is present distally. Plumose setae of body comprise 7–14 individual setae.

Description. Larva (n = 4)

Total length 3.6−3.8, 3.7 mm. Body yellow, abdomen pale blue.

Head Capsule ( Fig. 3B View FIGURE 3 ). Length 289–311, 300 µm, width 257–314, 282 µm, length/width 0.98−1.34, 1.06. Head capsule pale brown with mandible, mentum, postoccipital margin, labral margin, ungula all dark brown.

Antenna ( Figs 2C View FIGURE 2 , 3A View FIGURE 3 ). With 4 or apparently 5 segments; third segment long, entire or clearly divided into 2 parts (i.e. 5-segmented); second segment apically broadened. Ring organ near base of basal segment. Blade length 22–37, 31 μm. Lauterborn length 4–5, 5 μm. Style length 12–14, 13 μm. Antennal segment length (in μm): 58–67, 64, 13–15, 14, 22–26, 23, 5–6, 5, 4–5, 5. AR 1.27–1.45, 1.35.

Mandible ( Figs 2D, 2B View FIGURE 2 ). Length 84–91, 88 µm, Width 24–32, 29 µm. Apical tooth shorter than combined width of 3 inner teeth. Seta interna absent. Seta interna 6 branches, simple. Seta subdentalis 17–19, 18 µm long. A strong spine is situated on the inner margin of the mandible, immediately adjacent to the seta subdentalis, length 8–13, 11 µm.

Labrum ( Fig. 3C View FIGURE 3 ). All setae simple. Pecten epipharyngis has three large teeth. Premandible simple, the apical inner margin concave. Premandible length 50−60, 54 μm, with a broad inner tooth.

Mentum ( Figs 2E, 2F View FIGURE 2 , 3D View FIGURE 3 ). Mentum with 2 median teeth and 4 pairs of lateral teeth. Ventromental plate extended, cardinal beard long, with simple branches radiating from a common area, branches simple. Width 57–60, 59 µm. Paired median mental teeth 11–12, 12 µm wide.

Body ( Fig. 3E View FIGURE 3 ). Anal tubules length 152–180 μm (n = 2), exhibiting a medial constriction. Anal setae consist of five long setae and two short lateral setae. Abdominal segment I L1-L3 simple, L4 plumose, abdominal segment II L2 bifurcated, L4 plumose, L1 and L3 simple, Abdominal segments III–VII each with alternating simple and plumose setae, 2 of each setal type on each side of each segment. Plumose setae comprise 7–14 individual setae.

Remarks. Molecular analyses distinguished S. bifidus from the widely distributed S. semivirens and the Japanese endemic S. tamaparulus . The primary diagnostic character distinguishing the larvae of S. bifidus from S. semivirens is the simple branching pattern of the cardinal beard. S. semivirens is plumose on the apices of branches.

Biology. Algal attachment traces were observed in proximity to the larval abdomen, with Melosira varians C. Agardh, 1827 ( Fig. 4A View FIGURE 4 ) adhering near the posterior appendages and Pinnularia sp. ( Fig. 4B View FIGURE 4 ) and Navicula sp. ( Figs 4C, D View FIGURE 4 ) detected within the abdomen cavity. These findings suggest an ecological association with algal communities, potentially indicating either an algae-rich habitat or algivorous feeding behavior. It is consistent with observations from European populations ( Cranston 1979).

Ecological notes. The larvae of S. bifidus were discovered in a small stream downstream of a reservoir in the mountainous region of Zhejiang, China ( Fig. 5 View FIGURE 5 ).

Distribution. China (Sichuan, Yunnan and Zhejiang).