Heleniella parva Saether, 1985

Namayandeh, Armin, Hudson, Patrick L., Bogan, Daniel L. & Hudson, John P., 2024, Chironomidae (Diptera: Insecta) of Alaska, USA, with descriptions of new species and a checklist, Zootaxa 5511 (1), pp. 1-95 : 32-34

Heleniella parva Saether, 1985

Fig. 6A–H

Material examined. 1 male, 2 pharate male/pupae, 1 pharate female/pupa; USA, Alaska, J.B. E. R ., S. F. Chester Creek , 61.1898, -1497112, 12.vii.2017, leg. D. Bogan; dep. UAM .

Diagnosis. H. parva can be distinguished from other species of Heleniella by the combination of the following characteristics: The adult male with AR 0.7–1.0; well-reduced to absent anal point on a well-crested tergite IX. The adult female with AR 0.5; dorsocentrals almost twice as in male; tergites I–IX with rows of strong lateral shagreens; gonocoxite very small; seminal capsules large. The pupa has a thoracic horn with lateral and apical spines, surface with scatter spines; tergites II–VIII with a posterior row of simple spines and anteriorly with shallow scatter shagreens; sternite I with two anterolateral patches of long spines; sternite II with strong anteromedial patch of long spines and two shallow patches of anterolateral long spines; sternite III with an anteromedial patch of long spines.

Pharate female (n = 1)

Total length 3.0 mm.

Coloration. Head including antenna brown; legs lighter; halteres brown; abdomen greyish-brown.

Head. Antenna with 5 flagellomeres, last flagellomere with around 16 sensilla clavata ( Fig. 6A ), AR 0.5.

Thorax. Dorsocentrals 168 in several rows; scutals 70 in 4 rows; prealars around 35, antepronotal around 37; postnotum with 60 setae

Abdomen. Tergites I–IX with rows of strong lateral shagreens extending from base to apex of the segment.

Legs. Fore tibia spur 24 μm long; mid tibia spurs 15 and 13 μm long; hind tibia spurs 31 and 19 μm long; hind tibia comb with 16 spines. Lengths and proportions of legs as in Table 7.

Genitalia ( Fig. 6B–C ). Seminal capsules large and oval, 90 μm long and 52 μm wide ( Fig. 6B ). Notum 121 μm long. Gonapophysis VIII divided into large ventrolateral lobe and tongue-shaped dorsomesal lobe. Apodeme lobe distinct ( Fig. 6B ). Tergite IX divided in 2 circular setigerous patches, gonocoxite small, with around 16 long setae ( Fig. 6C ). Cercus with circular base and large pediform extensions, cercus 82 μm long and 41 μm wide.

Pupa (n = 3)

Total lenght 3.2 mm.

Coloration of mounted specimen. Exuvia golden-yellow

Cephalothorax. Thoracic surface wrinkled but no visible tubercles. Thoracic horn with lateral and apical spines; surface with scatter spines ( Fig. 6D ), thoracic horn 150–267 μm long and 33–38 μm wide; Pc 1–3 90, 112, 267 μm long (n = 1). Wing sheat 924 μm long.

Abdomen ( Fig. 6E–H ). Tergite I bare; tergites II–VIII with a posterior row of simple spines and anteriorly with shallow scatter shagreens ( Fig. 6E–F ); shagreen reduce in density towards tergite VIII. Sternite I with two anterolateral patches of long spines; sternite II with strong anteromedial patch of long spines and two shallow patches of anterolateral long spines; sternite III with an anteromedial patch of long spines ( Fig. 6G–H ). Anal lobe and genital sac longer in male than female; anal lobe 216–270, 252 μm long and 79–82, 81 μm wide; genital sac 116–196 μm long and 53–77, 67 μm wide; anal lobe with 3 subequal macrosetae, 98–116, 106 μm long ( Fig. 6E ).

Remarks

Saether (1985) described the adult male of this species based on the specimens from South Carolina and Tennessee. The three Alaskan adult males (including two pharate) we examined have an antennal ratio of 0.7–0.8, though other morphological characters identify as H. parva . Therefore, we modified the diagnosis of species to include the broader population within the Nearctic.

Figures

FIGURE 6. Heleniella parva Saether, 1984 adult female (A–C), pupa (D–H). A. antenna, B. genitalia ventral, C. genitalia dorsal, D. thoracic horn and precornial setae, E. tergites I–IX, anal lobes, genitalia sacs, and macrosetae, F. posterior simple spines of tergites, G. sternites I–III, H. anteromedial patch of long spines. Scale bars are 50 µm.