Cedrimyia, Namayandeh & Hudson, 2022

Namayandeh, Armin & Hudson, Patrick L., 2022, Two new Orthocladiinae (Diptera: Chironomidae) collected in overlooked places of Midwest USA, Zootaxa 5099 (1), pp. 120-128 : 121-123

Genus Cedrimyia gen. nov.

Figs. 1–2

LSID: urn:lsid:zoobank.org:act:7845E8DA-9E57-427D-80C5-BEE7B922A672

Type species. Cedrimyia margareti Namayandeh and Hudson , sp. n. by present designation.

Diagnostic characters. A combination of eyes with wedge-shaped dorsomedial extension; presence of 2 scalpellate acrostichals in centre of scutum; anterpronotal lobes without gap; tergite IX with curved ridge running close to mid-section of anal point; anal point long, bearing simple, short and weak setae, pointing posteriorly; virga consisting of two long spines; gonostylus with strong, comparatively darker spine-like setae; crista dorsalis thin and blade-like, stretching from mid to anterior of gonostylus separates Cedrimyia from most Orthocladiinae (see also the remarks section).

Etymology. The new genus is named after its type locality, Cedar Falls in Ohio. The suffix “ myia ” is Greek for the fly.

Description. Adult male. Small to medium size species up to 3.2 mm long. Wings up to 2.3 mm long.

Head ( Fig. 1a ). Antenna with 12 flagellomeres, 2 nd –3 rd segments and last flagellomere with sensilla chaetica. Eyes bare, with wedge-shaped dorsomedial extension. Temporal setae present, including inner verticals, postoculars and outer verticals. Tentorium narrow with small tentorial pit close to apex. Clypeus rectangular. Palp 5 segmented with third palpomere having sensilla clavata.

Thorax ( Fig. 1b ). 2 scalpellate acrostichals in centre of scutum. Dorsocentrals in single row, prealars few, scutellars in single row. Humeral pit small. Antepronotal lobes developed, narrowing anteriorly, without gap and bare.

Wing ( Fig. 1c ). Brachiolum, squama and R with setae. Other veins without setae. Costa extended. R 4+5 ends just above M 3+4. Anal lobe squared. Microtrichia visible at> 100 x magnification.

Legs. Mid and hind tibia with long sparse beard, hind femur with keel. Pulvilli absent. Fore tibia with 1 spur, each of mid and hind tibia with 2 spurs. Hind tibia comb developed.

Hypopygium ( Fig. 1d ). Tergite IX with curved ridge running close to mid-section of anal point. Anal point narrowly triangular, long, reaching close to the apex of inferior volsella, bearing simple, short, and weak setae, distributed evenly along its mid-section, and pointing posteriorly, apex rounded. Virga present consists of two long spines. Sternapodeme straight and thick. Phallapodeme collar bone-shaped. Inferior volsella a prominent triangular lobe. Gonostylus squat-shaped, well expanded in mid to anterior section, surface with strong, comparatively darker, spine-like setae; crista dorsalis developed, thin and blade-like, stretching from mid to anterior of gonostylus.

Adult female. Small species up to 2.1 mm long. Wing up to 2.4 mm long.

Head ( Fig. 2 a-b). Antenna with 5 flagellomeres, 3 rd –4 th segments and last flagellomere with sensilla chaetica. Eyes bare, with short dorsomedial extension. Temporal setae present, including inner verticals, postoculars, orbitals and outer verticals. Tentorium long and narrow with small tentorial pit close to apex. Clypeus rectangular. Palp 5 segmented with third segment bearing sensilla clavata.

Thorax. 2 scalpellate acrostichals in centre of scutum. Dorsocentrals in single row, prealars few, scutellars in single row. Humeral pit small. Antepronotal lobes developed, narrowing anteriorly, without gap and bare.

Wing ( Fig. 2c ). Brachiolum, squama, R and R 4+5 with setae. Other veins without setae. Costa extended. R 4+5 ends just above M 3+4. Anal lobe squared. Microtrichia visible at> 100 x magnification.

Legs. Mid and hind tibia with long sparse beard, hind femur with keel. Pulvilli absent. Fore tibia with 1 spur, each of mid and hind tibia with 2 spurs. Hind tibia comb developed.

Genitalia ( Fig. 2 d-e). Gonocoxite narrow and long with few setae. Seminal capsules small, semi-circular, spermathecal ducts without loops. Gonapophysis VIII divided into large ventrolateral lobe covering the base of smaller dorsomesal lobe. Apodeme lobe distinct. Tergite IX divided in 2 crescent-shaped setigerous light patches. Cercus with circular base and pediform extensions.

Remarks. The short and weak anal point setae; long, thin, and blade-like crista dorsalis of gonostylus; and the presence of dorsomedial extension of the eyes are probably autapomorphic in Cedrimyia . The presence of strong, comparatively darker setae on the surface of the Cedrimyia gonostylus can also be considered autapomorphic.

The presence of scalpellate acrostichals on scutum and long anal point of adult males resembles the species in Antillocladius Saether, 1981 , Litocladius Mendes, Andersen & Saether, 2004 , Lyrocladius Mendes and Andersen , 200, and Compterosmittia Saether, 1981 . The adult male of Cedrimyia can be distinguished from Antillocladius and Litocladius by a combination of short dorsomedial extension of the eye; only 2 scalpellate acrostichals in centre of scutum; short, weak, and posteriorly directed setae of anal point; virga consisting of two long and prominent spines; and thin blade-like crista-dorsalis of the gonostylus. The absence of lateral lamella of virga can further separate adult males of Cedrimyia from Litocladius . The setose squama of Cedrimyia adults can further separate them from Compterosmittia (See Mendes et al. 2004) . The presence of strong, comparatively darker setae on the surface of the Cedrimyia gonostylus is also a distinguishing character. Species of Lyrocladius have a laterally located strong setae on their gonostylus. The female of Cedrimyia can be distinguished from Antillocladius by a divided tergite IX with two setigerous protrusions, and a more prominent dorsomesal lobe of gonapophysis IX separates it from Litocladius . In their review of the Orthocladiinae genera with scalpellate acrostichals Mendes and Andersen (2008) placed Antillocladius , Litocladius , and Lyrocladius Mendes and Andersen, 2008 in the same monophyletic group based on the apomorphic characters such as scalpellate acrostichals, and similarity in the shape of anal point and its setation. Cedrimyia likely forms a sister group to this group.

Among other Orthocladiinae , the long anal point with weak lateral setae and the wedge-shaped eye extension bears some resemblance to Paraphaenocladius Thienemann, 1924 . A longitudinal ridge on tergite IX of adult males may resemble the species in Tavastia Tuiskunen, 1985 , and Mesosmittia Brundin, 1956 . Bare eye, absence of apical setae on the last antennal flagellomere, and bare wing of the adults separate Cedrimyia from those of Tavastia . The presence of scalpellate acrostichals in centre of scutum and a more prominent anal point separates Cedrimyia from those of Mesosmittia .

Figures

FIGURE 1. Cedrimyia margareti gen. n. sp. n., male. a. head; b. thorax; c. wing; d. hypopygium.

FIGURE 2. Cedrimyia margareti gen. n. sp. n., female. a. antenna; b. head; c. wing; d. genitalia ventral view; e. genitalia, dorsal view.