Symbiocladius wygodziskyi ( Roback, 1965 )

Velásquez-Rodríguez, Karen, Lin, Xiao-Long, Sánchez-Vendizú, Pamela, Loayza-Muro, Raúl, Huamantinco, Ana & Prat, Narcís, 2023, DNA Barcode of symbiotic chironomids: Findings in the genus Symbiocladius (Diptera: Chironomidae), Zootaxa 5319 (1), pp. 48-56 : 51-53

Symbiocladius wygodziskyi ( Roback, 1965)

The morphological analysis of the larval stage of S. wygodzinskyi agrees with the character descriptions given in Kieffer (1925), Roback (1965) and Gonser & Spies (1997) for mentum with 5–6 lateral teeth and the proximal tooth of the mandible long and slender. On the other hand, mature larvae have curved thoracic horns, gradually narrowing from the wide base to acute apex. Moreover, molecular analysis also supports morphological results. More detailed results are described below.

Larva

Body length: 1.94–2.33 mm (n = 2), maximum diameter: 0.36– 0.29 mm (n = 2).

Body with yellowish and slightly whitish coloration on the sides ( Fig. 2A–B ). Cephalic sclerotized capsule triangular in shape, 134.9–147.7 μm (n = 2) long, with a maximum width at the base of 135.3–139.3 μm (n = 2). Non-visible eye spots ( Fig. 2D ). Antenna with 5 segments, 14–18.1 μm (n = 3) long. Mandible, length: 25–28.7 μm (n = 4), heavily sclerotized, with two internal teeth, the more distal tooth is thicker than the proximal one. Mentum translucent not heavily sclerotized as the mandibles, wide central tooth, with 5–6 very acute lateral teeth at distal end. Short anterior prolegs with more than 90 hooks, which present one apical tooth and several internal teeth. Posterior prolegs with 19 hooks, these hooks do not have internal teeth.

Pupa

Mature larvae already display pupal features, including sclerotized thoracic horns. Body length: 3.15–4.10 mm (n = 2), maximum width (thorax): 1.02–1.03 mm (n = 2).

The body exhibits a gray coloration, with pale or light-colored spots mainly in the ventral and lateral region of the thorax. ( Fig. 2C ). Thoracic horn curved, tapering towards the distal end until ending in a very sharp projection, 127.4–143.3 μm (n = 4) total length, base of the projection is 23.7–35.6 μm (n = 4) wide ( Fig. 2E ). Abdomen has filiform spines on the tergites.

Ecological notes

Specimens were found living on nymphs of Leptophlebiidae (Ephemeroptera) . Larvae in process of pupation build a membranous sheath and were positioned from the II thoracic segment to the V abdominal segment of the host. The position of the larva on the host can be with the head forward or backward ( Fig. 2A–B ). There is no indication that Symbiocladius (A.) wygodzinskyi feeds on the hemolymph of its host. Finally, the host nymphs had very small translucent wing patches of the same size. Therefore, it was not possible to appreciate the effect of the commensal on the development of the wing patches.

Distribution: Department of La Libertad. Province: Sánchez Carrión. Municipality: Sarín. Chusgón River (a tributary of the Marañón River), 7°58’18.195” S, 77°57’51.962” W, m.a.s.l. Department: Apurímac. Province: Cotabambas. Municipality: Cotabambas. Anchapillay River (tributary of the Apurímac River), 14°2’57.8106” S, 72°24’6.8148” W, 4234 m.a.s.l. Department: Áncash. Province: Huaraz. District: Independencia. Churup River 9°29’14.70” S; 77°25’58.92” W, 4183 m.a.s.l. ( Fig. 1 )

DNA barcode analyses

The NJ tree based on partial COX1 gene shows two well supported major clades. The first clade is composed by species of Symbiocladius (99.5% of bootstrap support) from China and the second clade is formed by the species Symbiocladius (Acletius) wygodziskyi , the genera Nanocladius spp. and Epoicocladius spp. and Epoicocladius spp. (92.5% of bootstrap support) ( Fig. 3 ). This evidences that Symbiocladius does not form a monophyletic clade for COX1 genetree. These two clades recovered from Symbiocladius agree with the currently proposed subgenera, Symbiocladius and Acletius , presenting a genetic distance of 24.8±2%.

The first clade of Symbiocladius includes species of the subgenus Symbioclaidus : S. (S.) rithogenae and one not described yet, S. (S.) sp. 1XL that are genetically differentiated in 17.2±1.7% ( Table. 1 ). On the other hand, the second clade of Symbiocladius include the sequences generated in this study for Symbiocladius (A.) wygodziskyi , which differ from 19.4% to 26.4% with respect to the other species of Epoicocladius , and Nanocladius ( Table. 1 ).

Figures

FIGURE 1. Records in provinces or states of Symbiocladius in the world. Records of S. wygodzinskyi and Symbiocladius species with available COX1 sequences.

FIGURE 2. Symbiocladius wygodzinskyi, A–B, larva on a Leptophlebidae host, C, larvae in process of pupation on a Leptophlebidae host, D cephalic capsule, E thoracic horn.

FIGURE 3. Neighbor joining tree of partial COX 1 sequences (655bp) of some Orthocladinae species. Bootstrap values on nodes. Scale is based on the number of base substitutions per site. Tags shown the GenBank or BOLD system accession code| species|collection number|country of the record.