Tipula (Pterelachisus) octomaculata Savchenko

Salmela, Jukka & Autio, Olli, 2007, Redescription of Tipula octomaculata Savchenko, with notes on related Holarctic species (Diptera, Tipulidae), Zootaxa 1527, pp. 53-58 : 54-57

Tipula (Pterelachisus) octomaculata Savchenko

Figures 1a, 2a, 3a, b

Savchenko 1964: 44 (description), Fig. 19 (hypopygium lateral, 9th tergite dorsal, inner gonostylus lateral); Theowald 1980: 454, Fig. 355 (a 9th tergite dorsal, b inner gonostylus lateral, c outer gonostylus lateral, all redrawn after the original description).

Material examined: Finland, Ks: Taivalkoski, Lehtorinnanoja 7289411: 3560846, 3.7.- 4.8.2006 Malaise trap, J. Salmela leg, 1♂ (PCJS, in alcohol).

Other material studied: Tipula (Pterelachisus) angulata Loew USA: Minnesota, Clearwater Co # Itasca State Park, 4 July 1970 1500’, George W. Byers leg, 1 ♂ (ANS). Tipula (Pterelachisus) entomophthorae Alexander USA: Lake Tear 1310 m Essex Co. N.Y. 44.06.25-73.56.05 10 July 1980 McCabe & Teale leg, 1♂ (ANS). Tipula (Pterelachisus) trivittata Say Canada: Ontario, Ottawa 10 June 2001, F. Brodo leg, 1 ♂ (PCJS); Ont. Bells Corners 45°17’N, 75°48’W 2 July 1969 Fenja Brodo leg, 1 ♂ (PCJS).

Redescription: Male. Head. Top of head brown, rostrum light brown. Hairs covering head brown to dark brown. Antenna 13-segmented, scape, pedicel and 1st flagellomere light brown, other flagellomeres dark brown. Palpus light brown.

Thorax. General coloration of thorax brown (pruinosity not seen in specimens stored in alcohol, but holotype with grey pruinosity and three brownish prescutal stripes). Parts of post sutural scutum, katatergite, metakatepisternum and metaepimeron somewhat lighter. Stem of halter light, yellowish, knob infuscated. Wing 17 mm, patterned with light and dark areas. Dark clouds present at base of Rs, R2 and R3, tip of wing infuscated. Dark seams along CuA, CuA2 and distal half of A2. Discal cell and area around R1+2 light. Coxae dark brown, trochanters light brown. Base of hind femur light brown, other parts of leg missing. Other legs missing.

Abdomen. 1st segment of abdomen dark brown, 2nd segment yellowish, with narrow dark longitudinal stripe both dorsally and ventrally. Hairs of segments light. Male terminalia.

9th tergite (Fig. 1a) with deep median emargination, bearing two close spines in midpoint. Inner margin of emargination with blunt, weakly developed outgrowth. Gonocoxite characterized by relatively dense setosity ( Figs. 3 a, b), aedeagal guides conspicuous, darkly sclerotized. Outer gonostylus ( Fig. 2 a) humpbacked (subsigmoid), apically rounded, about three times longer than wide at mid point, bearing hairs subequal in length to width of outer gonostylus. Inner gonostylus ( Fig. 2 a) with conspicuous, sclerotized outer basal lobe, with sub-apical hyaline seta. Sub-basal spine sclerotized, lying along dorsal margin of inner gonostylus. Lower beak of equal width along its entire length, with moderate, pointed outgrowth on dorsal side of apex. Dorsal crest dark brown, resembling hammer in lateral view. Female unknown.

Discussion: The identity of the Finnish specimen is based on the original description by Savchenko (1964) and its subsequent translation by Theowald (1980). The holotype deposited at St. Petersburg was not studied by us directly, but we were able to examine photos of the holotype male. The similarity between the original description and the specimen from Finland is remarkable, so we do not hesitate to identify it as T. octomaculata . However, the only notable variation observed was that the sub-basal spine of the inner gonostylus is projected from the dorsal margin of the gonostylus in the holotype but lying along it in the Finnish specimen. According to the German translation of the original description ( Theowald 1980), the outer gonostylus (“od”), is “Einen breiten lanzettförmigen od”. The outer gonostylus was not entirely figured by Savchenko (1964), the apex of it is hidden by the 9th tergite, but Theowald has drawn the apex too, giving it an oval appereance, although Theowald did not see the specimen. Thus, we assume that the drawing by Theowald is misleading. In the Finnish specimen the outer gonostylus is humpbacked, widest at the midpoint, with the apex clearly narrower than the midpoint. Additionally, in the original description ( Savchenko 1964, Fig. 19) and subsequent translation ( Theowald 1980, Fig. 355 a) the 9th tergite in dorsal view is somewhat confusing.

Both the holotype and the specimen from Finland have somewhat wider, conical caudal lobes of the 9th tergite; the lateral outline of the 9th tergite in dorsal view is not as constricted as that figured by Savchenko (1964) and Theowald (1980); the outgrowth of the inner margin is blunt, not as sharp as that figured in Savchenko (1964) and Theowald (1980).

FIGURE 1. Male 9th tergite and inner gonostylus, dorsal view. a) Tipula octomaculata Savchenko , b) T. angulata Loew c) T. entomophthorae Alexander , d) T. trivittata Say.

Savchenko (1964) states that T. octomaculata is similar regarding the wing pattern to species around T. irrorata Macquart , T. procliva Alexander and T. caerulea Mannheims & Nielsen. However , T. octomaculata is clearly distinguished from T. irrorata and related species by the structure of 9th tergite. T. procliva has a quite similar inner gonostylus (see Alexander 1938, original description or Savchenko 1964, redrawn on p. 46), considering the dorsal crest and outer basal lobe, but the 9th tergite of T. procliva has a strong spine in the midpoint of the emargination whereas in T. octomaculata there are two close spines. T. caerulea is a synonym of T. laetibasis Alexander ( Oosterbroek 2006) , a species quite different from T. octomaculata in all aspects of male terminalia (see, for example Savchenko 1964; Martinovsky 1974).

There are not many species of Tipula (Pterelachisus) having a similar set of spines in the mid-point of the emargination of the 9th tergite. Of the Holarctic species, we found only T. trivittata having two spines in the 9th tergite (Fig. 1d). T. trivittata , however, has a pointed, well developed outgrowth in the inner margin of the emargination: this outgrowth is weak and blunt in T. octomaculata . Further, the basal part of the inner gonostylus in T. trivittata has no sclerotized, pointed lobe or sub-basal spine. In addition, the lower beak resembles a spoon: it is rounded and very wide distally. The outer gonostylus is digitiform, very narrow. The male 9th tergite of T. trivittata has been figured by Alexander (1919a; 1966).

Tipula angulata , a species quite close to T. trivittata , is distinguished from T. octomaculata by differences in the 9th tergite (Fig. 1b) (median emargination relatively small, only a weak protuberance in the mid-point, caudal margin truncate), outer gonostylus (digitiform and apex broadly rounded) and inner gonostylus (no spine in the outer basal lobe of the inner gonostylus; lower beak quite narrow compared to other species in lateral view). The male 9th tergite of T. angulata has been figured by Alexander (1966).

The closest relative of T. octomaculata is probably T. entomophthorae . The basic structure of the male hypopygia of the species is very similar, but in T. entomophthorae there is only a weak protuberance in the mid-point of the emargination of the 9th tergite (Fig. 1c); the inner margin of the emargination has a sub-basal, blunt outgrowth; the outer basal lobe of the inner gonostylus ( Fig. 2 b) is stronger in T. octomaculata ; the lower beak is relatively wide in the apical part ( Fig. 2 b); and the flap in the margin of the dorsal crest is roughsurfaced, whereas it is even in T. octomaculata . The male 9th tergite of T. entomophthorae has been figured by Alexander (1966). See also Alexander (1918) (original description) and Dietz (1921) (syn. T. similissima ).

Tipula (P.) penobscot Alexander, 1915 is probably a fourth Nearctic species close to T. octomaculata and related species. T. penobscot seem to have a strong outer basal lobe of the inner gonostylus ( Alexander 1915, plate XVIII, Fig. 32) but have a caudal margin of 9th tergite which is quite different than that of other species: there is no strong emargination, margin is concave, slightly notched, with a sharp outgrowth in the midpoint ( Alexander 1915, plate XIX, Fig. 45). In addition, Tipula (P.) diflava Alexander, 1919 ( Alexander, 1919b) perhaps should be mentioned here. This arctic species ( Brodo 1990) has a U-shaped median emargination of the 9th tergite, with a small median outgrowth in the midpoint; lobes of the caudal margin of the 9th tergite are oblique. The outer gonostylus is wide and rounded at the apex, the base is very narrow. The inner gonostylus has a pointed basal lobe and a sub-basal spine, but dorsal crest and beak without peculiar structures.

The holotype male of T. octomaculata was collected from Russia, Archangelskaja Oblast, Obozerskaja by N. Krivosheina from a spruce forest in 1959 ( Savchenko 1964; Theowald 1980). So far, the species has been known only from the type locality. The new discovery of the species in Finland is from the North boreal ecoregion (65°40’N) (see above Material examined). The locality is an approximately 150 m wide strip of old-growth forest surrounding a forest brook dominated by Norway spruce ( Picea abies ), deciduous trees being very scarce. The ground layer vegetation is characterized by tall herbs (eg. Filipendula ulmaria ) and ferns ( Dryopteris carthusiana, Phecopteris connectilis). Decaying spruce trunks are abundant at the site. Tipulid species such as Tipula limitata Schummel , T. pseudoirrorata Goethgebuer , T. grisescens Zetterstedt , T. variicornis (Schummel) and T. nubeculosa Meigen were also found at the site. The related Nearctic species discussed above are apparently confined to woods (eg. Alexander 1941; Petersen et al. 2005), except T. diflava , which is an arctic species ( Brodo 1990).

Figures

FIGURE 2. Male inner (a, b) and outer (a) gonostylus, lateral view, from outside. a) Tipula octomaculata Savchenko (sub-basal spine is drawn to different scale), b) T. entomophthorae Alexander.

FIGURE 3. Tipula octomaculata Savchenko, male hypopygium, ventral (a) and lateral view (b).