Orthocladius (Eudactylocladius) priomixtus, Ole & Saether, A., 2004

Ole & Saether, A., 2004, Three new species of Orthocladius subgenus Eudactylocladius (Diptera: Chironomidae) from Norway, Zootaxa 508, pp. 1-12 : 2-7

Orthocladius (Eudactylocladius) priomixtus sp. n.

( Figs 1 , 5–8, 12 )

Orthocladius (Eudactylocladius) mixtus ; Halvorsen et al, 1982: 119, pro parte, not Holmgren: 1869: 45.

? Spaniotoma (Orthocladius) mixtus ; Edwards, 1935: 538 not Holmgren: 1869: 45.? Orthocladius (Dactylocladius) ? microcomus ; Andersen, 1937: 67 not Kieffer 1922: 16.? Eudactylocladius mixtus ; Thienemann, 1941: 225 not Holmgren: 1869: 45.? Orthocladius (Eudactylocladius) mixtus ; Brundin, 1956: 98 not Holmgren: 1869: 45.

Type material

Holotype ď, NORWAY: Hordaland, Evanger, Ekse, Malaise trap, 10–18 viii 1976, T. Andersen ( ZMBN Type No. 394). Paratype: NORWAY: Luster, Jostedal, near Viva, 1 ď, 29 vii 1987, G. A. Halvorsen & O. A. Saether.

Other material: NORWAY: Sogn & Fjordane, Luster, Jostedal, Fåbergstølsgrandane, 1 pupal exuviae 25 vii 1986, Ø. A. Schnell ( ZMBN).

Etymology

From Latin, prior, prius, former, and mixtus , mix, mingle, referring to the former position of the species in O. (E.) mixtus and the confused status of several species within the subgenus.

Diagnostic characters

The male imago is separable from the other species of the subgenus except O. (E.)

subletteorum by having inner margin of gonocoxite with strong dense microtrichiae, commencing about one fourth gonocoxite length posterior of gonocoxite base, combined with weakly delimited superior volsella, and no sensilla chaetica on the legs. It differs from O. (E.) subletteorum by having a preapical, triangular projection of the gonostylus. The tentatively associated pupa differs from the tentative pupa of O. (E.) subletteorum by having no pleural spinules. It has all three macrosetae equal in size, pedes spurii B at most indicated on segment II, pedes spurii A present only on sternite VI, tergites II–VII each with paired median spine patches, and tergites II–VIII with posterior rows of spines.

Nomenclatorial notes: Edwards in Thienemann (1941) suggested that Orthocladius novae­Semliae Kieffer, 1922: 14, and Dactylocladius microcomus Kieffer, 1922: 16 , could be synonyms of O. (E.) mixtus . O. novaesemliae is lost and must be regarded as a nomen dubium. The type of Dactylocladius microcomus has been examined. It is a Chaetocladius lacking the abdomen and thus also a nomen dubium.

Male imago (n = 2 except when otherwise stated)

Total length 3.64–3.73 mm. Wing length 2.32–2.49 mm. Total length/wing length 1.50–1.57. Wing length/length of profemur 2.80–2.85. Coloration yellowish with blackish brown vittae, lower 2/3 of preepisternum, median anepisternum II, and postnotum.

Head. AR 1.10–1.15. Ultimate flagellomere 510–539 m long. Temporal setae 11–14, including 4–5 inner verticals, 4–5 outer verticals, and 3–4 postorbitals. Clypeus with 6–12 setae. Cibarial pump, tentorium and stipes as in Fig. 8 . Tentorium 154–173 m long, 41– 45 m wide. Stipes 161–173 m long, 53–56 m wide. Palpomere lengths (in m): 38– 41, 53–54, 128–131, 113–120, 165–184.

Thorax. Antepronotum with 5–6 setae. Dorsocentrals 12–14, acrostichals 14, prealars 5. Scutellum with 10–12 setae.

Wing. VR 1.09–1.11. Costal extension 41–56 m long. R with 7–11 setae, R1 with 0–3 setae. Squama with 13–20 setae.

Legs. Spur of front tibia 64 m long, spurs of middle tibia 38–45 and 26–30 m long, of hind tibia 71–75 and 34 m long. Width at apex of front and middle tibia each 45–49 m, of hind tibia 53– 56 m. Pseudospurs present on ta1 and ta2 of mid and hind leg, 26–38 m long. Sensilla chaeticae absent. Lengths (in m) and proportions of legs

Hypopygium ( Fig. 1 ). Tergite IX with 20–27 setae including 8–12 on anal point, laterosternite IX with 6–8 setae. Anal point 68–71 m long. Phallapodeme ( Fig. 12 ) 66–68 m long, transverse sternapodeme ( Fig. 12 ) 116–131 m long, oral projections well developed. Gonocoxite 240–244 m long. Gonostylus 86–90 m long, widest near apex, with triangular preapical projection not visible in all views; crista dorsalis apical, bluntly triangular; megaseta 17–19 m long. HR 2.67–2.83, HV 4.15–4.23.

Cephalothorax. Frontal setae not measurable. Thoracic horn lost. Precorneal setae respectively 94 m, 75 m and 45 m long. Anterior dorsocentral (Dc1) 83 m long; Dc2, 30 m, Dc3 45 m, and Dc4 38 m long. Distances (in m): Dc1–Dc2 203, Dc2–Dc3 0, Dc3–Dc4 15.

Abdomen ( Figs 5–7 ). Tergites II–VII each with 2 spine patches, each patch with 13 – 22 spines. Longest spine in patches 8 m long on tergite II, 11 m on T III, 15 m on T IV, 19–23 on each of T V–VII. Tergites II–VIII with posterior rows of spines, triple on T II– VII, double on T VIII, 70–76 spines on T II–IV, 84 on T V, 66 on T VI, 52 on T VII, and 39 on T VIII. Longest posterior spine 9–11 m long on each of T II–IV, 15–19 m long on each of T V–VIII. Integuments II/III – V/VI each with 5 rows of anteriorly directed spines with no true caudal hooklets on tergite II. Tergite I without shagreen; tergites II–VIII with strong anterior shagreen not connected to spine patches, IX with anterior and median spinules. Sternites I and IX bare; sternites II–VIII each with sparse anterior group shagreen. Pedes spurii A indicated only on sternite VI ( Fig. 7 ). Pedes spurii B indicated on tergite II only. Longest L seta on segments I–VI at most 56 m long. Lengths of L1–L4 setae on segment VII (in m) as: 19, 56, 23, 11; on segment VIII: 19, 34, 60, 75.

Anal lobe 281 m long. Anal macrosetae subequal in length, 191 m long, 0.68 as long as anal lobe. Male genital sac overreaching anal lobe by 68 m.

C omments

O. (E.) priomixtus could conceivably be a form of O. (E.) subletteorum . The differences are slight and mainly consist in the shape of the gonostylus. In O. (E.) subletteorum the gonostylus is broadest about the mid­point and has an apical, strong, rounded crista dorsalis nearly as high as the megaseta, while the gonostylus of the present species is clearly broadest near the apex and has an inner triangular projection and a more triangular and lower crista dorsalis. However, according to B. Bilyj (personal communication) the differences in the shape of the gonostylus may be due to position on the slide preparation. He also found that his specimens had prominent oral projections on the transverse sternapodeme as in O. (E.) priomixtus and different from the drawing of O. (E.) subletteorum in Cranston (1999 fig. 1g). O. (E.) priomixtus is slightly larger with a wing length of 2.3– 2.4 mm as opposed to 1.8–2.1 mm in O. (E.) subletteorum , the squama has 13–20 setae as opposed to 9–14, and the anal point is 68–71 m long as opposed to 32– 51 m.

If the tentatively associated pupa is correctly associated the two species have to be different. The pupa also differs from the pupa regarded as belonging to O. (E.) mixtus by Thienemann as it has posterior spine rows also on tergite VIII. This, however, could be individual variation.

Distribution

The species is known with certainty only from the localities mentioned here, three high mountain localities in Western Norway, the two in Jostedal, glacier­fed streams about 2 km apart. Most other records are likely to be of O. (E.) gelidorum . The paratype from Viva have previously been reported as O. (E.) grampianus (Edwards) = O. (E.) gelidus Kieffer by Saether & Schnell (1988) who also give further details of the Viva locality.

Figures

FIGURES 1 – 4. Orthocladius (Eudactylocladius) spp., male imagines, hypopygium, 1: O. (E.) priomixtus sp. n. with variation of gonostylus, 2: O. (E.) schnelli sp. n., 3: O. (E.) musester sp. n., 4: O. (E.) fuscimanus (Kieffer).

FIGURES 5 – 7. Orthocladius (Eudactylocladius) priomixtus sp. n., pupa, 5: tergites I – V, 6: tergites VI – IX, 7: sternite VI.

FIGURES 8 – 17. Orthocladius (Eudactylocladius) spp., male imagines, 8 – 11: tentorium, stipes and cibarial pump, 8: O. (E.) priomixtus sp. n., 9: O. (E.) schnelli sp. n., 10: O. (E.) musester sp. n., 11: O. (E.) fuscimanus (Kieffer), 12 – 17: sternapodeme and phallapodeme, 12: O. (E.) priomixtus sp. n., 13: O. (E.) olivaceus Kieffer, 14: O. (E.) schnelli sp. n., 15: O. (E.) gelidorum (Kieffer), 16: O. (E.) fuscimanus (Kieffer), 17: O. (E.) musester sp. n.