Hydrobaenus laticaudus Saether

Makarchenko, Eugenyi A., Makarchenko, Marina A. & Semenchenko, Alexander A., 2019, Morphological description and DNA barcoding of Hydrobaenus laticaudus Saether 1976 (Diptera: Chironomidae: Orthocladiinae) from Amur River basin (Russian Far East), Zootaxa 4674 (2), pp. 225-234 : 226-230

Hydrobaenus laticaudus Saether

( Figs. 1–18 )

Hydrobaenus laticaudus Saether, 1976: 80 , Fig. 25; Makarchenko et al. 2009: 39, Figs. 19–24; Ashe & O’Connor 2012: 316. Material. Russian Far East, Amur River basin: 8 adult males, Jewish Autonomous Region, Smidovichsky District, Nature Reserve “Bastak”, Zabelovskoye Lake , N 48°25’57.3”, E 134°12’50.0”, 16.IV.2008, leg. V. Lubarets ; 2 mature pupae (male), 1 mature pupa (female), 4 mature larvae, the same data, except 19.IV.2019, leg. E. Makarchenko ; 28 adult males, the same data, except 20.IV.2019, leg. E. Makarchenko ; 2 adult males, the same data, except Bolshoye Lake at the river channel Pemzemskaya, near Priamursky Village , 1.V. 2009, leg. N. Yavorskaya ; 2 adult males, Khabarovsk Territory, Amursky District, Kharpi River (low stream), Bolon’ Lake basin, 3.V.2008, leg. N. Yavorskaya ; 7 adult males, Khabarovsk Territory, Khabarovsky District, Bolshekhekhtsirsky Nature Reserve , Chirka River , N 48°05’951”, E 134°51’115”, 29.IV.2019, leg. N. Yavorskaya ; 2 adult males, the same data except unnamed stream near Korphovsky Village , N 48°12’939”, E 135°02’619”, 11.V.2019, leg. N. Yavorskaya ; 2 adult males, Khabarovsk Territory, Nanaisky District, Sindinskoye Lake , N 48°54′57.6″, E 136°11′09.6″, 12.V.2009, leg. N. Yavorskaya.

Adult male (n=7). Total length 3.5–4.7 mm. Total length/wing length 1.39–1.57.

Head. Eyes naked, with short dorso-median prolongations. Temporal setae: 1–3 outer verticals, 4–5 inner verticals and 5–8 postorbitals. Clypeus with 10–17 setae. Antenna with 13 flagellomeres and well developed plume; 13 th flagellomere 860–880 µm long; AR 2.45–2.56. Length of palpomeres (in µm): 30–34, 70–96, 120–152, 92–140, 144–176; palpomere 3 with 1–3 sensitive hairs in apical part; length of 1–5 palpomeres/head width 0.87.

Thorax. Dark brown. Antepronotum with 7–10 lateral setae. Ac 2–8 (very short and situated in middle of mesonotum), Dc 9–17, Pa 7–13, Scts 9–18 in one row.

Wing. Greyish. Length 2.5–3.1 mm. R with 5–9 setae, R 1 without setae, R 4+5 with 0–1 seta apically. R 4+5 ending distally of apex M 3+4. Costa extension 40–100 µm long. Cu 1 curved in apical part. Anal lobe well developed and strongly protrude ( Fig. 1 ). Squama with 23–44 setae.

Legs. Spur of fore tibia 68–88 µm long. Spurs of mid tibia 25–28 µm and 30–36 µm long. Spurs of hind tibia 30–100 µm and 16–25 µm long. Hind tibial comb with 12–14 setae. Basitarsus of hind leg with 4 sensilla chaetica in basal part. Lengths and proportions of legs as in Table 1 .

Hypopygium ( Figs. 2–6 ). Tergite IX roundish, with 35–54 setae and short, poorly developed, rounded triangular and bare in distal part anal point. Laterosternite IX with 12–15 setae. Transverse sternapodeme 156–160 µm long, with rounded triangular projections. Virga 18–32 µm long, consisted of 4 setae. Gonocoxite 300–372 µm long; inferior volsella as shown in Figs. 2–4 . Gonostylus 128–160 µm long, wide, distally angular, with small protrusion on outer edge ( Figs. 2–6 ); megaseta 8–13 µm long.

Pupa (n=3). Total length 4.0– 4.9 mm. Cephalothorax brownish, abdominal tergites light brownish or yellowish. Exuviae transparent. Tergites II–VIII and sternites II–VIII with brown or dark brown apophyses.

Cephalothorax. Frontal apotome with 2 setae 100–140 µm long and with poorly developed or reduced warts. Antepronotum with two median antepronotals setae ca 100 µm long and two lateral antepronotal setae ca 70 µm long; both median and lateral antepronotals thin and hair-like. Thoracic horn 448–464 µm long, covered by spinules, expands to the rounded apex ( Figs. 7–8 ). Precorneal setae lengths (in µm): Pc 1 80–92, Pc 2 72–120, Pc 3 40–60. Bases of setae arranged in form of triangle. Dorsocentrals hair-like; Dc 1– 4 48 –80 µm long. Distance between Dc 1 and Dc 2 32–64 µm; between Dc 2 and Dc 3 48–66 µm; between Dc 3 and Dc 4 36–92 µm.

Abdomen. Tergite I without shagreen. Tergite II with shagreen of spinules in middle of posterior half; shagreen at posterior edge with relatively large spinules in 4 rows, their apex pointed orally ( Fig. 9 ). Tergites III–IV with shagreen of spinules at least covered of ½ tergite surface, sometimes whole surface of tergite; size of spinules slightly increases toward the posterior margin; 2–3 rows of larger spinules along posterior margin with apex pointed orally. Shagreenation of tergites V–VI similar to the same of tergites III–IV but spinules of posterior margin are much smaller and tergite VI without rows of spinules along posterior margin. Tergite VII with fine shagreen in middle part from anterior to posterior margins. Tergites VIII–IX without shagreen but sometimes tergite VIII may be with very tender shagreen. Sternites I–IX without shagreen. Segment II with PSB. Sternites IV–VII with PSA. Segment I with 0–1 pair of lateral setae. Segments II–III with 2–3 pairs of hair-like lateral setae. Segments IV–VI with 3 pairs of hair-like lateral seta. Segments VII–VIII mostly with 4 pairs of taeniate lateral setae, and one specimen with 3 pairs of taeniate lateral setae on segment VIII from one side only ( Fig. 10 ). Anal lobe 368–416 µm long and 192–216 µm width, with fringe of 37–40 setae from one side, which 72–104 µm long, occupy all lateral part of anal lobe edge to base of megasetae ( Fig.10 ); anal lobe length/anal lobe width 1.7–2.0. Male genital sac overreaching anal lobe on 60 µm, without apical papilla. Anal macrosetae 236–260 µm long.

Fourth instar larva (n = 4). Total length 5.4–7.2 mm.

Head. Light-yellowish, with postoccipital margin, teeth of mentum, mandible and premandible dark brown or almost black; head length 320–368 µm. Labral setae S I plumose, with 12–14 unequal branches ( Fig. 11 ); labral lamella simple; S II – S IV simple and hair-like. Pecten epipharyngis consisted of 3 equal pointed scales. Premandible distally with 2 apical teeth ( Fig. 13 ). Antenna with 5 segments; length 1–5 segments (in µm): 59–62: 12–16: 8–10: 6–8: 3–5; AR 1.59–1.91; apex of segment 2 with stylus and lauterborn organs ending at apex of 3 rd segment; antennal blade 32–38 µm long, ending near base of 5 th segment; one large ring organ in proximal 1/3 of basal segment and one small ring organ in apical half ( Figs.14–15 ). Mandible with apical tooth, which equal or shorter of combined width of three inner teeth; seta interna with 5–7 of 5 poorly serrated branches, seta subdentalis long and wide, with rounded apex ( Fig. 12 ). Mentum with 2 median and 6 pairs of dark brown or black lateral teeth; median teeth well divided, one of them in 1.5 time wider than first lateral tooth; first lateral tooth is strongly inclined to median tooth. Setae submenti at level of posterior edge of ventromental plates. Ventromental plates extending beyond last lateral tooth ( Figs. 16–17 ); ventromental plate maximum width/one median tooth width 0.67–1.0. Postmentum 144–168 µm long. Maxilla with pecten galearis.

Abdomen. Procercus 32–44 µm long (length/width 2.0), with 7 anal setae 400–560 µm long and 2 thin lateral setae. Supraanal setae 304–352 µm long; Sa/An 0.54–0.88. Anal tubules elongated, egg-shaped, shorter than poste- rior parapods. Posterior parapods with simple hooks in apex.

Taxonomic notes. H. laticaudus was described by Saether (1976) from Alaska on adult males and placed in H. conformis group. But since the pupa and larva were not known, the author had some doubts and wrote in the remarks that “At first glance the hypopygium of this species appears to resemble some members of Zalutschia more than other species of Hydrobaenus ”. After studying the pupa and larva, we confirm the position of H. laticaudus in the genus Hydrobaenus .

In our earlier work ( Makarchenko & Makarchenko 2014) we compared adult males from Alaska with those from the Amur River basin but did not note the characteristic feature of males from the Amur River basin, which have a more developed and protruding forward anal lobe of the wing ( Fig. 1 ). In description of males from Alaska Saether (1976) recorded that “anal lobe ... slightly protruding”. The characteristics of pupae and larvae, comparing of H. laticaudus with closely related species, are given below in our updated keys based on that by Makarchenko & Makarchenko (2014: 431), as well as in the results of DNA barcoding.

Distribution. H. laticaudus is known only from Alaska ( U.S.A.) and Amur River basin (Russian Far East).

Figures

FIGURES 1–6. Adult male of Hydrobaenus laticaudus Saether. 1, anal lobe of wing; 2, 4, gonocoxite and gonostylus; 3, hypopygium in dorsal view; 5–6, gonostylus.

FIGURES 7–17. Pupa (7–10) and larva of fourth instar (11–17) of Hydrobaenus laticaudus Saether. 7–8, thoracic horn; 9, tergite II; 10, tergites VII–VIII and anal segment; 11, SI of labrum; 12, distal part of mandible; 13, premandible; 14–15, antenna; 16–17, mentum. Scale bars: Figs. 7–8—100 µm; Figs. 9–10—200 µm; Figs. 11–17—20 µm.

FIGURE 18. Bayesian phylogenetic tree of the genus Hydrobaenus and Parakifferiella sp. as outgroup based on the mitochondrial cytochrome c oxidase I (COI) barcode gene sequences (657-658 bp). The phylogenetic reconstruction was performed with using SYM+I, F81+I and GTR+G for each codon position. Bayesian posterior probabilities (PP) given in tree nodes. Specimens obtained in this study are in bold.

FIGURES 7–17. Pupa (7–10) and larva of fourth instar (11–17) of Hydrobaenus laticaudus Saether. 7–8, thoracic horn; 9,

Tables

TABLE 1. Lengths (in µm) and proportions of leg segments of Hydrobaenus laticaudus Saether, male (n=5)

	fe	ti	ta 1	ta 2	ta 3	ta 4	ta 5	LR	BV	SV	BR
P 1	896-1088	1040-1312	704-896	400-528	304-370	208-224	168-170	0.68-0.74	2.39-2.59	2.49-2.75	2.9-4.3
P 2	928-1120	1008-1200	480-592	288-336	208-260	144-176	144-168	0.48-0.52	2.98-3.11	3.71-4.03	2.0-3.8
P 3	1008 -1248	1184-1472	608-800	336-448	288-330	160-190	144-180	0.51-0.54	2.93-3.14	3.40-3.61	3.1-5.2