Orthocladius (Saether, 2005)

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 : 64-67

Orthocladius v. d. Wulp, 1874

The genus Orthocladius , like Cricotopus , is a very speciose genus. Historically, the identification of Orthocladius specimens has been afflicted by taxonomic and nomenclatural confusion.These were caused by incongruence between the immatures and adults ( Cranston 1999; Saether 2005). This problem is partially solved by using subgenera to help separate the many species of Orthocladius ( Saether 2005) . All six subgenera are represented in Alaska, and keys to all stages can be found in Cranston (1999), Cuppen & Tempelman (2022), Dettinger-Klemm (2001), Langton & Cranston (1991), Rossaro et al. (2003), Saether (2004a, b, 2005), and Soponis (1977, 1990).

Six species of Orthocladius (Eudactylocladius) Thienemann, 1935 are recorded from Alaska. Three pupae of Orthocladius (Eudactylocladius) dubitatus Johannsen, 1942 were collected by Dave Wartinbee from a pool on the Portage Glacier in the Southcoastal region in mid-July and verified by Cranston (1999). Cranston (1999) noted that the larvae of this species inhabit a wide variety of habitats. We collected adults of Orthocladius (Eudactylocladius) gelidorum (Kieffer, 1923) from a first-order stream near Lena Point north of Juneau in mid-July. This is the first faunistic record of this species in the United States. Dave Wartinbee collected two pupae of Orthocladius (Eudactylocladius) gelidus Kieffer, 1922 from a first-order stream entering Tustumena Lake on the Kenai Peninsula. This species and O. gelidorum may be sympatric in their distribution, occurring in permanent summer-flowing rivers and streams ( Cranston 1999). Webb et al. (2022) identified Orthocladius (Eudactylocladius) mixtus (Holmgren, 1869) from Willow Creek in Wrangell-St. Elias National Park based on the DNA barcoded larvae. In mid-July, pupae of Orthocladius (Eudactylocladius) olivaceus (Kieffer, 1911) were collected from Little Togiak Lake in Southwestern Alaska and a first-order stream entering Tustumena Lake on the Kenai Peninsula ( Cranston 1999). We collected adults of O. olivaceus from a seep near Nugget Falls in Juneau in mid-May and from a first-order stream near Lena Point in mid-July. We collected an adult male of Orthocladius (Eudactylocladius) subletteorum Cranston, 1999 in a drift net sample in late June in a distributary of the Yukon River in the delta area. This is the first faunistic record of this species in the United States. Cranston (1999) reported O. subletteorum from emergence traps over damp soil and inundated pond and lake margins on Ellesmere Island, Nunavut, Canada. Additional records are the larvae of Orthocladius (Eudactylocladius) collected from the Kuskokwim River by Hayford et al. (2014) and streams on St. Matthew Island by Sikes et al. (2016). We collected larvae of Orthocladius (Eudactylocladius) from the Yukon River, a tallus stream on Unalaska Island, and a tributary of the Herbert River below the Herbert Glacier.

Eight species in the subgenus Ortholadius ( Euorthocladius ) Thienemann, 1935 have been collected in Alaska. Orthocladius (Euorthocladius) annellae Saether, 2005 , identified as Orthocladius (Eurorthocladius) rivicola Kieffer, 1911 , was collected by a car-top trap in Southcoastal Alaska along the Seward, Glenn, and Parks Highways (Highways 1, 3 and 9) in mid-June and late September ( Sommerman & Simmet 1965; see also Saether, 2005). We collected larvae of O. annellae from a seep near Nugget Falls near Juneau. Webb et al. (2022) DNA barcoded larvae of Orthocladius (Euorthocladius) ashei Soponis, 1990 from Coal Creek in the Yukon-Charley Rivers National Preserve. Dave Wartinbee collected a male pupa of Orthocladius (Euorthocladius) coffmani Soponis, 1990 in mid-July from a glacier pool associated with the Portage Glacier ( Soponis 1990). We collected adults of O. coffmani from the Tangle River in mid-August. Soponis (1990) collected the exuviae of O. coffmani from cold waters of mountain streams and found adults emerging in April and July. We collected larvae of Orthocladius (Euorthocladius) luteipes Goetghebuer, 1938 from a third-order tributary to the Mulchatna River, a new faunistic record for Alaska. We also collected a larva near O. luteipes from Wasilla Creek. However, antennal blade is much longer in this larva than O. luteipes and the Lauterborn organ is smaller and not robust. The antennal ratio of this larva is 0.86, whereas that of O. luteipes is 1.50–1.88. Soponis (1990) reported on the collection of pupal exuvia of Orthocladius (Eurorthocladius) rivicola Kieffer, 1911 in a drift net from an unnamed creek above Galbraith Camp in early July. We collected an adult near Montana Creek near Juneau in mid-August. We collected larvae of O. rivicola from a sub-alpine stream on Baranof Island, a third-order tributary to the Mulchatna River, Deep Creek on the Kenai Peninsula, and from a seep near Nugget Falls near Juneau. The larvae of O. rivicola make and live in gelatinous tubes covered with sand and detritus cemented to rocks ( Soponis 1990). Brabets & Ourso (2013) also reported O. rivicola from Denali National Park as a group designation. Orthocladius (Euorthocladius) rivulorum Kieffer, 1909 has been reported from the Dietrich and Atigun Rivers in the Brook Range by Tilley (1979) as Orthocladius (Euorthocladius) Alaska sp. III ( Soponis 1990) and from Denali National Park by Brabets & Ourso (2013). We found larvae of O. rivulorum in Cottonwood Creek and several streams in the Mat-Su Valley along the Parks Highway including Goose and Troublesome Creeks. We have also collected larvae from Crooked and Deep Creeks and the Ninilchik River on the Kenai Peninsula, as well as Chester and North Fork Campbell Creeks in Anchorage. We have found O. rivulorum larvae in many streams in Southwestern Alaska, including the Little Mulchatna and Chilchitna Rivers. Soponis (1990) reported O. rivulorum inhabiting stones and sometimes moss in fast-flowing brooks, streams, and rivers. Records of Orthocladius (Euorthocladius) saxosus (Tokunaga, 1939) come from a pool on Portage Glacier where Dave Wartinbee collected two pupal exuviae ( Soponis 1990) in mid-July. An additional record is from a DNA barcoded larva by Webb et al. (2022) from Central Alaska, but no specific location was given. We collected larvae of this species from Little Rabbit Creek near Anchorage. Soponis (1990) found the larvae of this species inhabiting clear, irregular gelatinous tubes 10–16 mm long and 3–5 mm wide, closely adhering to stones along small crevices in fast-flowing mountain streams. Orthocladius (Euorthocladius) thienemanni Kieffer, 1906 pupal exuviae were found at two locations, the North Fork of the Chena River in mid-July and the Jim River where it crosses the Dalton Highway (Highway 11) ( Soponis 1990). We collected larva from Deception Creek in the Mat-Su Valley. Soponis (1990) reported that the larvae inhabit flowing water in clear gelatinous tubes encrusted with sand grains, often in fissures and depressions of a stone. Other larval records assigned to the subgenus are reported from Denali National Park ( Brabets & Ourso 2013), Kuskokwim River ( Hayford et al. 2014), and St. Matthew Island ( Sikes et al. 2016).

The reports of the subgenus Mesorthocladius Saether, 2005 from Alaska are Orthocladius (Mesorthocladius) frigidus (Zetterstedt, 1838) and Orthocladius (Mesorthocladius) roussellae Soponis, 1990 . Sikes et al. (2016) tentatively identified O. frigidus from St. Matthew Island. We collected O. frigidus from several areas in Southeast Alaska, including Fish Creek on Douglas Island, the Antler River, and seeps associated with Nugget Fall in Juneau. We also found larvae from Cottonwood and Wasilla Creeks. Our findings are new faunistic records for this species in Alaska. Soponis (1990) reported collecting three pupal exuviae of O. roussellae from a pool associated with the Portage Glacier in mid-July. We collected two larvae from seeps associated with Nugget Falls near Juneau. We also collected larvae from a tributary to the Yukon River in Yukon-Charley Rivers National Preserve, and a glacial stream in Lake Clark National Park. Additionally, larvae of O. ( Mesorthocladius ) have been collected from the Kuskokwin River by Hayford et al. (2014) and St. Matthew Island by Sikes et al. (2016).

The subgenus Orthocladius (Orthocladius) v. d. Wulp, 1874, with 16 species, is the most diverse subgenus reported in Alaska. Sommerman & Simmet (1965) collected adult males of Orthocladius (s.s.) appersoni Soponis 1977 along the Glenn Highway (Highway 1) between Palmer and Anchorage in late June. We collected an adult male of this species from the outlet of the Antler River into Berners Bay in mid-May. We collected larvae of Orthocladius (s.s.) charensis Soponis, 1977 from the East Alsek River, Glacier Bay National Park and Preserve. This is the first faunistic record of this species from Alaska. Soponis (1977) notes that larvae of O. charensis inhabit the rocky zones of lakes and do not build tubes. We collected larvae of Orthocladius (s.s.) clarkei Soponis, 1977 from Steambath Creek, a fourth-order tributary to the Newhalen River in the Bristol Bay area. The larvae of this species prefer streams and are univoltine in their emergence pattern ( Soponis 1977). O. clarkei is a new faunistic record for Alaska. Watson et al. (1966) reported Orthocladius (s.s.) decoratus (Holmgren, 1869) from Ogotoruk Creek along the Northwest Coast of Alaska and Webb et al. (2022) DNA barcoded the larvae from Willow Creek in Wrangell-St. Elias National Park. Males of Orthocladius (s.s.) dentifer Brundin, 1947 were collected with a car-top trap by Sommerman & Simmet (1965) along Seward Highway (Highway 9) on the Kenai Peninsula between Seward and Primrose in mid-June and along the Glenn Highway (Highway 1) near Palmer ( Soponis 1977). We collected larvae of this species from seeps associated with Margaret Creek on Revillagigedo Island. Soponis (1977) found this species in both standing and running waters. We collected Orthocladius (s.s.) dorenus ( Roback, 1957) larvae from Steambath Creek, Bristol Bay area. Sikes et al. (2016) also made a tentative identification of larval specimens of this species from St. Matthew Island. This is a new faunistic record for Alaska. Sommerman & Simmet (1965) collected adult males of Orthocladius (s.s.) hellenthali Soponis, 1977 in Anchorage in early September ( Soponis 1977). The larval habitat of this species is unknown; however, adults are usually captured near flowing waters ( Oliver & Dillon 1997). We collected adults of Orthocladius (s.s.) knuthi Soponis, 1977 from the Tangle River in mid-August and a pharate male from the Yukon River delta area in early July. This is a new faunistic record for Alaska. Milner (1994) reported larvae of Orthocladius (s.s.) mallochi Kieffer, 1919 from a new stream following glacial recession in Glacier Bay National Park and Preserve. Watson et al. (1966) found Orthocladius (s.s.) nitidoscutellatus Lundström, 1915 (as Orthocladius trigonolabis (Edwards, 1924)) in the Ogotoruk Creek Area. Oliver & Dillon (1997) and Brundin (1956) suggested this species' larvae inhabit lakes. In mid-July, we collected males of Orthocladius (s.s.) oblidens (Walker, 1856) in drift nets set in a distributary of the Yukon River in the delta area. This is a new faunistic record for Alaska. Oliver & Dillon (1997) note that the larvae of this species live in flowing water and lakes. Soponis (1977) reported Orthocladius (s.s.) obumbratus Johannsen, 1905 from Chitina, Alaska, from the Kenai Peninsula along Sterling Highway (Highways 1) from mid-June to late August and from St. George Island in mid-June. We collected larval specimens of O. obumbratus from a small creek associated with the Herbert Glacier, Antler River, and seeps associated with Nugget Falls near Juneau; Margaret Creek, Revillagigedo Island; from a moss-covered wet rock face near the mouth of Eagle River near Juneau; and from Grey’s, Cottonwood, Deception, Meadow, and Little Meadow Creeks in the Mat-Su Valley. We collected larvae of Orthocladius (s.s.) oliveri Soponis, 1977 from a seep associated with Nugget Falls, a new faunistic record for Alaska. Soponis (1977) found larvae of this species associated with Elodea mats and filamentous green algae clinging to submerged twigs, weeds and branches close to shore. She found emerging adults soon after ice breakup and swarming occurred late in the afternoon. Our only record of Orthocladius (s.s.) rubicundus (Meigen, 1818) is a larva from the Alsek River in Glacier Bay National Park and Preserve which is a new faunistic record for Alaska. There is also a tentative identification of a larvae from St. Matthew Island ( Sikes et al. 2016). Oliver & Dillon (1997) note that larvae of this species inhabit a variety of habitats including springs, flowing water, and the littoral region of standing water. We collected a pupa of Orthocladius (s.s.) wiensi Saether, 1969 from Answer Creek in mid-June and larvae from Deception Creek both in the Mat-Su Valley which represents a new faunistic record for Alaska.

There is only one species in the subgenus Orthocladius (Pogonocladius) Brundin, 1956 , Orthocladius (Pogonocladius) consobrinus (Holmgren, 1869) . We collected an adult from the Tangle River in mid-August and a larva from a tributary of the Kalikpik River along the western North Slope of Alaska. This is a new faunistic record for Alaska. A larvae identified to this subgenus has also been reported from St. Matthew Island ( Sikes et al. 2016). Lindegaard (1992) found this species most abundant in the littoral zone of an Icelandic lake. Namayandeh & Beresford (2019) reported this species as far north (79 ⁰N) as Fosheim Peninsula on Ellesmere Island, Nunavut where pupa and adult males were collected from Hot Weather Creek in July with water temperature close to 8.4 ℃.

Orthocladius (Symposiocladius) lignicola Kieffer, 1914 has been reported from Alaska, as Orthocladius (s.s.) tryoni ( Soponis, 1977) (see Saether 2005). This record was based on an adult male collected using a car-top trap along Glenn Highway (Highway 1) between Palmer and Anchorage ( Soponis 1977) in late June. We collected a larva from Caswell Creek in the Mat-Su Valley, larvae from a small tributary to Six Mile Lake near Nondalton, larvae from two small streams on Revillagigedo Island, and from Freds Creek near Sitka. This species is known to mine in submerged wood in the Nearctic where it prefers alder and hazel (Cranston 1988). Bowser et al. (2020) collected larvae of Orthocladius (Symposiocladius) smolandicus Brudin, 1947 from the Miller Creek watershed, based on DNA barcode data. There is also a report of an unknown larva collected in the Sanctuary River, Denali National Park ( Arctos 2023).