Zavrelia parapentatoma, Namayandeh & Hudson & Ghaderi & Stott, 2023

Namayandeh, Armin, Hudson, Patrick L., Ghaderi, Edris & Stott, Wendylee, 2023, Zavrelia parapentatoma (Chironomidae: Diptera), a curious new species from North America, revealed by molecular methods, Zootaxa 5249 (1), pp. 111-124 : 115-118

Zavrelia parapentatoma sp. nov.

Figs. 3–4

LSID: urn:lsid:zoobank.org:act:3AEFFA97-108E-493C-91A4-7CCCE57A5E91

Type material. Holotype male; USA, Michigan, Washtenaw Co., Ervin-Stucki Preserve ; 42.136730°, -83.981339°; 8.vii.2021; leg. Patrick Hudson; deposited at ARC . Paratypes: 3 males, 1 female; same as holotype. 1 male, 1 female; USA, Michigan, Washtenaw Co., Ervin-Stucki Preserve ; 42.136730°, -83.981339°; 8.v.2022; leg. Patrick Hudson; deposited at ARC . 5 pupae, 5 larvae; USA, Michigan, Washtenaw Co., Ervin-Stucki Preserve ; 42.136730°, -83.981339°; 8.vi.2022; leg. Patrick Hudson; deposited at ARC .

Diagnostic characters. Zavrelia parapentatoma can be separated from other Zavrelia species by the following combination of characters: Adult male with wing length ~ 1.3 mm, 4–5 longer than broad; AR 1.19; frontal tubercle minute, ~4 μm long; anal point with numerous (35) long spinulae (at least 8 times as long as wide) placed between long anal crest and flexing with their pointed ends directed anteriorly; 8 long median tergite setae placed on 1–3 light roundish fields at mid tergite IX; median volsella short, stout, with simple and subulate lamellae. Adult female with AR 0.23–0.28; temporal setae 8; frontal tubercle small, ~6 μm long; sternite VIII with 30 setae; notum including rami 131–170, 151 μm long; coxosternapodeme with developed anterior and posterior lobes. Pupa with cephalic tubercle weak and short; the median patch of microspinules much more prominent on tergites II–V but not wellextended to the lateral edge; those in II-IV appear divided with only a few microspinules in between; tergite II with small anterior patches of lateral shagreens; lateral shagreens prominent and extend along the lateral edge of tergites III–VI; segment VIII with a simple or bifid posterolateral spur; anal lobe seta taeniate. Larva with AR 0.93–1.23; AAR 0.64–0.77, 0.70; AHR 0.31–0.36, 0.30; ventromental plates medially reaching the border of the second and third lateral teeth of mentum; MVR 1.00–1.18, 1.11.

Etymology. The new species is named after its similarity to Z. pentatoma . The prefix “ para ” is Latin, meaning “near” or “close”.

Description. Male (n = 5).

Total length 1.7–1.9, 1.8 mm. Wing 1.3 mm long and 0. 3 mm wide.

Coloration of the mounted specimen. Head, thorax, and tergites brown. Legs and sternites yellowish brown. Wing and halters greyish-brown.

Head. Plume well-developed; antenna with 10 flagellomeres, ultimate flagellomere with 2 sensilla clavata ( Fig. 3A ); AR 1.12–1.29, 1.19. Frontal tubercle minute, 4 μm long. Temporal setae with only 2 inner verticals. Tentorium 99–110, 105 μm long ( Fig. 3B ). Clypeus squared about 82 μm long and 89 μm wide, with 10 setae 78–94 μm long. Third palpomere with 1 sensillum clavatum; lengths of palpomeres (in μm): 46–70, 53; 30–42, 38; 93–116, 105; 76–88, 83; 92–106, 97.

Thorax chaetotaxy. Ac 12; Dc 9; Pa 1; Scts 4–5.

Wing ( Fig. 3C ). Wing 4–5 times longer than wide. R with 17–20 setae, R 1 with 6–7, R 4+5 with 18–19 setae. VR 1.5. Wing cell setation mainly confined to the wing apex.

Legs. Fore leg tibia with 40 μm long spur; mid and hind legs tibiae with well-separated combs; mid leg tibial combs 12 μm long, and spurs 13–16 μm long; hind leg tibia with combs 9–11 μm long and spurs 13–17 μm long. Lengths and ratios of leg segments as in Table 1 .

Hypopygium ( Fig. 3D–E ). Tergite IX 103–129, 114 μm long and 60–86 μm wide, with 8 median setae on 1–3 light roundish fields, and 20 apical setae. Anal point 42–58, 50 μm long and 20–24, 22 μm wide (maximum); with 2 lateral setae close to the base; well-developed crests present; 33–37, 35 very long spinulae present between crests of anal point ( Fig. 3D–E ). Gonocoxite 64–70, 67 μm long; gonostylus 47–54, 49 μm long; HR 1.30–1.5, 1.4. Superior volsella 42–45 μm long, digitiform, medially directed, with 3 dorsal and 3 median setae on setiger; median volsella stout with cluster of simple and subulate, lamella, stem 16–19, 17 μm long; inferior volsella club-shaped, 37–52, 49 μm long with several distal setae, dorsal surface without microtrichia. HV 3.6.

Female (n = 2).

Total length 1.8–1.9 mm. Wing 1.3 mm long and 0.32 mm wide.

The coloration of the mounted specimen. Same as male.

Head. Antennae with 5 flagellomere ( Fig. 3F ) with ultimate flagellomere 59–61 μm long, AR 0.23–0.28, 0.26. Temporal setae 8. Frontal tubercle small, 6 μm long. Tentorium 107–116, 112 μm long. Clypeus with 12 setae, setae 77 μm long. Lengths of palpomeres (in μm): 40–49, 44; 27–37, 32; 71–80, 76; 62–63; 94.

Thorax chaetotaxy. Ac 8; Dc 7; Pa 1; Scts 6.

Wing. Wing L/ W 3.8 –4.0. Brachiolum with 2 setae; R with 19 setae, R4+5 with 24 setae, R1 with 7 setae. Wing membrane setation same as in male. VR 1.5–1.6.

Legs. Foreleg tibial spur with 23 μm long; mid and hind legs tibiae with well-separated combs; mid leg tibial spurs 16 μm long; hind leg tibial spurs 9–11 μm long. Lengths and ratios of leg segments as in Table 2 .

Genitalia ( Fig. 3G ). Tergite IX 138–163, 151 μm long. Sternite VIII with 30 setae. Gonocoxite with 1 seta. Notum including rami 131–170, 151 μm long, notum alone 83–102, 92 μm long. Seminal capsule 56 μm in diameter (n = 1). Coxosternapodeme with developed anterior and posterior lobes. Cercus 49 μm long and 30 μm wide.

Pupa (n = 5).

Total length 2.2–2.3 mm; abdomen 1.6–1.7 mm long.

Colouration of the pupal exuviae. Pale brown. Lateral margins of abdominal segment VIII much darker.

Cephalothorax: Cephalic tubercle weak and short, 18–29, 22 μm. Taeniate frontal seta 135–149, 142 μm long ( Fig. 4A ). Pedicel sheath tubercle absent. Thoracic horn 248–428, 349 μm long, 18–28, 22 μm wide, with few spines in mid-section ( Fig. 4B ); precorneals taeniate, Pc 1–3 136, 183, 196 μm long (n = 1). Wing sheath 699–754, 725 μm long and 177–195, 187 μm wide.

Abdomen ( Fig. 4C ): Tergite I bare. Tergites II–IX with median patch of microspinules. Median patch of microspinules much more prominent on tergites II–V and not well extended to the lateral edge; those in II–IV appear divided in the middle with only a few microspinules; the median patch of microspinules on tergites VI–IX reducing gradually and well-divided. Pleura II with small anterior patches of lateral shagreens; lateral shagreens prominent and extend along the lateral edge of pleura III–VI. No visible lateral shagreens on pleura VII–IX. Tergite II with pedes spuri B and posterior hook row of 50–60, 55 hooks, 120–155, 137 μm wide. Sternites bare. Segment II–III with 3 simple lateral setae; segment IV with 2 simple and 1 taeniate lateral setae; segment V–VII with 4 taeniate lateral setae; segment VIII with 3 taeniate lateral setae and a simple to bifid posterolateral spur, spur 29–35, 32 μm long. Anal lobe 108–123, 116 μm long and 61–83, 74 μm wide; genital sac 163–190 μm long and 50–69 μm wide; anal lobes with fring of 16–17 taeniate setae of 73–112, 90 μm long; anal lobe seta taeniate 77–81, 79 μm long.

Larva (n = 5).

Total length 2.9–3.3, 3.0 mm, case 2.9 mm long.

Coloration. Head capsule brown, mentum, inner teeth of mandibles, and occipital region darker. Abdomen yellowish brown.

Head: HL/HW 0.84–1.05, 0.9. AR 0.93–1.23, 1.1; antennal pedestal 55–64, 57 μm long with well developed, 29–31, 30 μm long spur; antennal segment lengths (in μm): 73–88, 82; 32–40, 37; 18–22, 19; 11–15, 13; 7–8; third segment inserted subapically on segment two; AAR 0.64–0.77, 0.70; AHR 0.31–0.36, 0.30; antennal blade 113–114 μm long; Lauterborn organs 17–26, 22 μm long ( Fig. 4D ). Labral SI comb-like, SII plumose, SIII simple. S3 simple, 86–104, 95 μm long. Premandible 49–53, 51 μm long; quartered and with a well-developed brush ( Fig. 4E ). Mandible 82–88, 84 μm long, with 1 subapical, 1 apical, and 3 inner teeth; setae subdentalis 48–56, 51 μm long, reaching well-beyond apical tooth; setae interna with 3 blades of well-branched spines ( Fig. 4F ). Mentum with one median tooth and six lateral teeth; first lateral teeth slightly lower than second and third; ventromental plates medially reaching the border of the second and third lateral teeth of mentum ( Fig. 4G ); MVR 1.00–1.18, 1.11.

Body: Posterior parapod 86–102, 94 μm long and 124–133, 130 μm wide, with 16 simple claws. Procercus 23–29, 24 μm long and 23–29, 26 μm wide; each procercus with 4 apical setae, 2 shorter 372–404, 380 μm long, and the 2 longer 502–679, 617 μm long; subapical seta 163–188, 171 μm long; supranal seta 237–255, 248 μm long. 4 conical anal tubules present, 73–92, 82 μm long.

Taxonomic remarks. The Z.parapentatoma and Z.pentatoma are close species and probably form a sister group. The morphological characters that separate the two species are, at the most, very subtle. There are many overlapping sizes and ratios between both species, which makes the distinction between the two species difficult ( Table 3 ). For adult males, the only distinguishing character is the spinulae of the anal point, which in Z. parapentatoma are much longer (at least 8 times as long as wide) compared to Z. pentatoma (no more than 4 times as long as wide). Females of both species are hard to separate; the range of notum and ramus length combined may be slightly different between the two species, with Z. parapentatoma being in the higher range. The wing venarum ratio of adults of both species also differs slightly, with Z. parapentatoma having the higher ratio. The pupae of both species show the most significant difference among life stages. Z. parapentatoma has median patches of microspinules on tergites II–V less extended, and those in II–IV appear divided in the middle with only a few microspinules. Additionally, the anal lobe seta is prominent and taeniate in Z. parapentatoma . Z. pentatoma has a well-extended and joined patch of microspinules on tergites II–V, and the anal lobe seta is simple. Few characters could separate the larva of Z. parapentatoma from that of Z. pentatoma including the extent of the ventromental plates, size of Lauterborn organs, length of the shortest anal setae, and length of the anal tubules. In Z. parapentatoma ventromental plates medially reach the border of the second and third lateral teeth of the mentum, whereas in Z. pentatoma hardly reach the third lateral teeth. Z. parapentatoma has a slightly longer and narrower Lauterborn organ, and its shortest-anal setae and anal tubules are also longer than those of Z. pentatoma .

Figures

FIGURE 3. Zavrelia parapentatoma sp. nov., male (A-E), female (F-G). A. antenna; B. head; C. wing; D. hypopygium, dorsal and ventral view; E. anal point; F. antenna; G. genitalia. dorsal view. Scale bars represent 50 µm.

FIGURE 4. Zavrelia parapentatoma sp. nov., pupa (A-C), larva (D-G). A. frontal apotome; B. thoracic horn; C. abdomen; D. antenna; E. premandible; F. mandible; G. mentum. Scale bars represent 50 µm.

Tables

TABLE 2. Female leg lengths (μm) and proportions of Zavrelia parapentatoma sp. nov.

	fe	ti	ta1	ta2	ta3	ta4	ta 5	LR	BV	SV
p 1	487	366	501	245	181	113	70	1.37	2.2	1.7
p 2	555	466	271	118	116	60	52	0.58	3.7	3.8
p 3	627	557	326	167	136	80	67	0.59	3.4	3.6