Allocladius lusciniolus Saether et Andersen

Saether, Ole A. & Andersen, Trond, 2011, Chironomidae from Gough, Nightingale and Tristan da Cunha islands, Zootaxa 2915, pp. 1-19 : 15-18

Allocladius lusciniolus Saether et Andersen

( Figs 28–35 )

Allocladius lusciniolus Saether et Andersen in Ferrington and Saether, 2011: 57.? cf. Parakiefferiella sp. Holdgate (1965: 396)

Bryophaenocladius sp., pro parte (Jones et al. 2003)

A preliminary description was given in Ferrington and Saether (2011: 57).

Type material. Holotype female, TRISTAN DA CUNHA: Site 7, on rim, west of patches, above Molly Gulch, below Dailies Hill, 37o108'44"S, 12°326'53"W, 2270 ft., Blechnum palmiforme -grassland mix, 15–21.ii.2005, Malaise trap, C. Hänel ( ZMBN). Paratypes: 20 females, as holotype; 2 females, Site 9, Sandy Point, behind the hut, 37o114'47"S, 12o219'61"W, 102 ft., woodland shrub, fruit and forest trees, 21.ii.2005, C. Hänel ( BMNH, TCD, ZMBN). NIGHTINGALE ISLAND: 1 female, Site 8, 1st Pond furthest from the path, 37o25'616"S, 12o29'302"W, mire wetland with pool surrounded by Scirpus spp., 30.iii.–01.iv.2005, C. Hänel; 4 females, Site 10, 3rd Pond close to top of path, 37o25'533"S, 12o29'102"W, mire wetland, Scirpus spp., fernbush spp. and mosses, 26–28.iii.2005, Malaise trap, C. Hänel ( TCD, ZMBN). GOUGH ISLAND: 3 females, Site SB1 at Seal Beach, 40o20'667"S, 0 9o 53'199"W, boulder beach, 5 m a.s.l., 2000, Malaise trap, C. Hänel & A.G. Jones; as previous except: 3 females, SG2a in the lower part of Snoek Gat, 40o20'437"S, 0 9o 52'943"W, tussock-grassland, 25 m a.s.l.; 2 females, SG2b in the upper part of Snoek Gat; 1 female, TD2 at Tumbledown, 40o20'990"S, 0 9o 53'291"W; 2 females, SB3 on Seal Beach, 40o20'659"S, 0 9o 53'215"W, tussock-fernbush, 50 m a.s.l.; 3 females, AD1 at Admirals, 40o20'293"S, 0 9o 53'008"W; 2 females, SG 3 in Snoek Gat, 40o20'441"S, 0 9o 52'974"W; 4 females, ET1 East of Tumbledown, 40o20'881"S, 0 9o 53'285"W; 2 females, TD3 at Tumbledown, 40o20'979"S, 0 9o 53'290"W; 2 females, BA1 at the Base (weather station), 40o20'516"S, 0 9o 53'028"W, fernbush, 50–100 m a.s.l.; 4 females, BR1 at bridge over the stream behind the weather station, 40o20'407"S, 0 9o 53'228"W; 1 female, PC1 at Prion Cave, 40o20'724"S, 0 9o 53'354"W; 3 females, WA1 west of Admirals, 40o20'380"S, 0 9o 53'980"W; 1 female, SO2 at Sophora river, 40o19'070''S, 0 9o 54'268''W; 2 females, DA1 at dam in the river behind the weather station, 40o20'318"S, 0 9o 53'345"W, fernbush, 100–150 m a.s.l.; 1 female, FS1 at ‘First Stop’ by the stream along transect from the weather station towards Tafelkop, 40o20'227"S, 0 9o 53'367"W; 2 females, SB2 on the coastal inland cliffs at Seal Beach, 40o20'668"S, 0 9o 53'210"W, tussock grassland; 1 female, TK3 on Tafelkop at stream, 40o19'960"S, 0 9o 53'806"W, fernbush, 350–400 m a.s.l. ( BMNH, TCD, ZMBN).

Etymology. Diminutive of Latin luscinia, the nightingale, referring to the occurrence on Nightingale Island.

Diagnostic characters. The species differs from other known females of the genus by having 1–5 setae apically on M1+2. The lack of a supraalar combined with sharply pointed posterolateral corners of tergite X and sternite VIII without anteromedian setae will separate the species from other described species of the genus except A. wirthi (Freeman) . From A. wirthi the species differs in being much smaller, having fewer dorsocentrals (9–12 as opposed to 14–21), longer costal extension (94–120 µm as opposed to 50–64 µm), fewer setae on abdomen and smaller seminal capsules.

Description. Female (n = 10). Total length 1.49–1.80, 1.60 mm. Wing length 0.90–1.01, 0.94 mm. Total length / wing length 1.58–1.80, 1.71. Wing length / length of profemur 2.83–3.08, 2.94.

Coloration. Pale brown with vittae, anterior part of preepisternum, scutellum, and notum dark brown. Legs and abdomen brown.

Head. AR 0.27–0.33, 0.30. Lengths (in µm) of flagellomeres: 64–75, 71; 45–49, 48; 47–53, 49; 43–49, 45; 60– 68, 64. Sensilla chaetica about 30 µm long. Temporal setae 4–5, 4 including 1–2, 1 very weak inner vertical and 3 outer verticals. Clypeus with 4–9 setae. Tentorium, stipes and cibarial pump as in Figure 28 . Tentorium 79–120, 94 µm long; 9–23, 13 µm wide. Stipes 98–143, 102 µm long; 23–38, 27 µm wide at plate. Palpomere lengths (in µm): 19–26, 22; 28–39, 34; 49–68, 60; 53–60, 59; 71–83, 78. Third palpomere with 1 very weak lanceolate sensilla clavata about 9 µm long. No coronal suture.

Thorax ( Fig. 29 ) Median antepronotal lobes reduced, 1–4, 2 lateral setae on antepronotum. Dorsocentrals 9–12, 10; acrostichals 3–6, 4, very weak and not visible in most specimens; prealars 2–4, 3; supraalar seta absent. Scutellum with 6 setae.

Wing ( Fig. 30 ). VR 1.27–1.30, 1.32. Anal lobe reduced. Wing punctuation relatively coarse. Costal extension 94–120, 107 µm long. R4+5 ending distal to apex of M3+4; Cu1 sinuate. Brachiolum with 1 seta; costa between FR and apex of R4+5 with 27–40, 33 non-marginal setae; costal extension with 6–14, 9 non-marginal setae; R with 9– 10, 9 setae; R1 with 4–6, 5; R4+5 with 12–15, 13; M1+2 with 1–5, 2 apical setae; other veins bare.

Legs. Spur of fore tibia 19–24, 23 µm long; spurs of mid tibia 19–24, 22 µm and 17–23, 20 µm long; of hind tibia 34–41, 39 µm and 15–23, 20 µm long. Width at apex of fore tibia 23–26, 24 µm; of mid tibia 24–30, 26 µm; of hind tibia 30–38, 33 µm. Comb of 9–10, 10 setae; longest seta 23–34, 29 µm long; shortest 18–23, 21µm long. Lengths and proportions of legs as in Table 6.

fe ti ta1 ta2

p1 293–350, 320 302–373, 328 180–217, 198 99–113, 108

p2 321–392, 347 340–406, 363 161–194, 171 80–95, 85

p3 331–397, 357 359–435, 384 208–246, 225 95–113, 105

ta3 ta4 ta5 LR

p1 61–76, 71 38–43, 41 33–38, 36 0.57–0.63, 0.61

p2 57–66, 58 33–43, 38 28–38, 33 0.45–0.49, 0.47

p3 95–113, 102 33–47, 40 28–43, 36 0.57–0.60, 0.59

BV SV BR

p1 3.09–3.49, 3.33 3.17–3.49, 3.28 1.8–2.8, 2.4

p2 3.93–4.39, 4.14 4.00–4.35, 4.15 2.3–3.3, 2.7

p3 3.31–3.58, 3.44 3.17–3.39, 3.29 2.4–3.6, 3.1 Abdomen. Tergites with two transverse rows of setae. Number of setae on tergites I–VIII as: 2–6, 4; 9–16, 12; 12–18, 14; 11–21, 15; 12–21, 15; 12–18, 15; 10–14, 13; 12–14, 12. Number of setae on sternites I–VIII as: 0; 0; 0– 2, 1; 0–3, 2; 2–9, 5; 3–10, 5; 3–6, 5; 20–30, 24.

Genitalia ( Figs 31–35 ). Gonocoxite low, without distinct posterior projection, with 3 strong setae and a few strong microtrichia. Tergite IX more or less divided, with altogether 10–18, 15 setae. Cercus 60–71, 65 µm long. Segment X with long, sharp posterolateral corners. Seminal capsule 53–64, 55 µm long; 34–41, 39 µm wide; microtrichia not observed; spermathecal ducts with loop, with weak bulbs before common opening. Notum 79–94, 87 µm long.

Pupa and larva. Unknown.

Remarks. This apparently parthenogenetic species is very similar to A. wirthi (Freeman, 1961) from Australia, A. conigerus (Freeman, 1954) from eastern, southern and central Africa including Reunion and A. azoricus (Storå, 1945) from the Azores, all having numerous non-marginal setae on costa proximal to apex of R4+5 and segment X with triangular posterolateral corners ( Ferrington & Saether 2011). Allocladius lusciniolus may be the parthenogenetic sister species of A. azoricus . Similar pairs of species are found both within Allocladius Kieffer [( A. nanseni (Kieffer, 1926) and A. arenarius ( Strenzke, 1960) ] and within the closely related Pseudosmittia Edwards, 1932 . Until recently the present female probably would have been identified as Parakiefferiella sp. among other because of the long costal extension. Allocladius Kieffer, 1913 recently has been separated from Pseudosmittia ( Andersen et al. 2010; Ferrington & Saether 2011) and especially the females of both genera may have a long costal extension. We regard it as likely that the cf. Parakiefferiella sp. mentioned in Holdgate (1965: 396) from Tristan da Cunha actually refers to A. luciniolus . The specimens from Gough Island were misidentified as Bryophaenocladius sp. in Jones et al. (2003) because of the relatively heavy punctuation on the wing membrane.

Distribution. The species is known from Gough, Tristan da Cunha and Nightingale Island.

Figures

FIGURES 28 – 35. Allocladius lusciniolus Saether et Andersen, 2011, female. 28 — tentorium, stipes and cibarial pump; 29 — thorax; 30 — wing; 31 — genitalia, ventral view; 32 — genitalia, dorsal view; 33 — ventrolateral lobe; 34 — dorsomesal lobe; 35 — apodeme lobe.