Hydraena impressicollis Fairmaire

Hydraena impressicollis Fairmaire

Figs. 29 (habitus), 31 (aedeagus), 224 (gonocoxite and spermatheca), 240 (map)

Hydraena impressicollis Fairmaire 1898b: 468.

Type Material. Lectotype (male): Labels on lectotype: " Madagascar Diego-Suarez Ch. Alluaud 1893; TYPE [red]; MUSEUM PARIS MADAGASCAR Collection Leon Fairmaire 1906; Hydraena impressicollis Frm Madag; TYPE [red]; LECTOTYPE Hydraena impressicollis Fairmaire 1898, design. P. D. Perkins 2015 [red]". One female paralectotype: "Madagascar Diego-Suarez Ch. Alluaud 1893; Hydraena impressicollis Frm type; [female symbol]; PARALECTOTYPE Hydraena impressicollis Fairmaire 1898, design. P. D. Perkins 2015 [red]" (MNHN).

Specimens examined (550): Antsiranana, Joffreville (M. d'Ambre), first right affl. below Grande Cascade, linear spring area, elev. 966 m, 12° 30' S, 49° 10' E, 26 iii 2011, R. Gerecke (MD 187o) (36 NMW); Joffreville, (M. d'Ambre), puddles near bellevue point way to sommet d'Ambre, elev. 1163 m, 12° 32' S, 49° 10' E, 25 iii 2011, R. Gerecke (MD 184) (2 NMW); Joffreville (M. d'Ambre), riparian spr. at r. affl. R. de Manques, in Res. Fontenay, elev. 650 m, 12° 32' S, 49° 10' E, 18 xi 2001, Gerecke & Goldschmidt (MD 157) (4 NMW); Joffreville (M. d'Ambre), riparian springs at right border of R. Antomboka downstream sacred cascade, elev. 1000 m, 12° 32' S, 49° 10' E, 19 xi 2001, Gerecke & Goldschmidt (MD 160) (2 NMW); Montagne d'Ambre, Antsahampano, Makis R., immed below Grande Cascade, N:-12.47540, E:49.21730, 12° 28' S, 49° 13' E, 19 xi 2004, Monaghan, Andriamparany, Ottke (P2302) (1 NHRS); Montagne d'Ambre, Grande Cascade, elev. 740 m, 13° 34' S, 49° 10' E, 1 xi–30 xii 2004, M. Balke (MD 004) (61 ZSMC); Montagne d'Ambre, Grande Cascade, stream parallel to, elev. 800 m, 13° 34' S, 49° 10' E, 1 xi–30 xii 2004, M. Balke & D. Ottke (MD 005) (75 ZSMC); Montagne d'Ambre, Petit Cascade [near Gite], elev. 1020 m, 12° 30' S, 49° 10' E, 1 xi–30 xii 2004, M. Balke & D. Ottke (MD 002) (53 ZSMC; one male " MNCN AI-541 DNA specimen"); Parc National Montagne d'Ambre, 12.2 km 211° SSW Joffreville, malaise trap in montane rainforest, elev. 1300 m, 12° 35' S, 49° 9' E, 2–7 ii 2001, Fisher, Griswold et al. (BLF 2853) (2 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01A-02, elev. 960 m, 12° 30' S, 49° 10' E, 26–29 i 2001, M.E. Irwin, E.I. Schlinger & R. Harin’Hala (8 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01A-06, elev. 960 m, 12° 30' S, 49° 10' E, 11–12 ii 2001, R. Harin’Hala (10 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01A-08, elev. 960 m, 12° 30' S, 49° 10' E, 4–19 iii 2001, R. Harin’Hala (9 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01A-09, elev. 960 m, 12° 30' S, 49° 10' E, 19 iii–5 iv 2001, R. Harin’Hala (11 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01B-04, elev. 975 m, 12° 31' S, 49° 11' E, 25 i–11 ii 2001, M.E. Irwin, E.I. Schlinger & R. Harin’Hala (5 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01B-05, elev. 975 m, 12° 31' S, 49° 11' E, 1 ii–4 iii 2001, M.E. Irwin, E.I. Schlinger & R. Harin’Hala (5 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01B-06, elev. 975 m, 12° 31' S, 49° 11' E, 4–19 iii 2001, M.E. Irwin, E.I. Schlinger & R. Harin’Hala (11 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01B-07, elev. 960 m, 12° 30' S, 49° 10' E, 19 iii–5 iv 2001, M.E. Irwin, E.I. Schlinger & R. Harin’Hala (5 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-03, elev. 1125 m, 12° 31' S, 49° 10' E, 29 i–11 ii 2001, R. Harin’Hala (7 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-05, elev. 1125 m, 12° 31' S, 49° 10' E, 4–19 iii 2001, R. Harin’Hala (4 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-06, elev. 1125 m, 12° 31' S, 49° 10' E, 19 iii–5 iv 2001, R. Harin’Hala (5 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-07, elev. 1125 m, 12° 31' S, 49° 10' E, 5–21 iv 2001, R. Harin’Hala (15 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-08, elev. 1125 m, 12° 31' S, 49° 10' E, 21–26 iv 2001, R. Harin’Hala (7 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-09, elev. 1125 m, 12° 31' S, 49° 10' E, 26 iv–12 v 2001, R. Harin’Hala (7 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-10, elev. 1125 m, 12° 31' S, 49° 10' E, 12–14 v 2001, R. Harin’Hala (5 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-11, elev. 1125 m, 12° 31' S, 49° 10' E, 14–30 v 2001, R. Harin’Hala (15 CAS); Parc National Montagne d’Ambre, malaise trap MA-01-01D-12, elev. 1125 m, 12° 31' S, 49° 10' E, 30 v–6 vi 2001, R. Harin’Hala (3 CAS); Diego-Suarez, 7 km N of Joffreville, dry forest; malaise trap MA- 01-07-08, elev. 360 m, 12° 20' S, 49° 15' E, 6–20 iii 2001, R. Harin’Hala (7 CAS); 7 km N of Joffreville, dry forest; malaise trap MA- 01-07-09, elev. 360 m, 12° 20' S, 49° 15' E, 20 iii–7 iv 2001, R. Harin’Hala (7 CAS); 7 km N of Joffreville, dry forest; malaise trap MA- 01-07-10, elev. 360 m, 12° 20' S, 49° 15' E, 7–27 iv 2001, R. Harin’Hala (5 CAS); 7 km N of Joffreville, dry forest; malaise trap MA- 01-07-12, elev. 360 m, 12° 20' S, 49° 15' E, 13–16 v 2001, R. Harin’Hala (1 CAS); Montaigne Francais, malaise along forested limestone ridge MA- 01-06-07, elev. 150 m, 12° 18' S, 49° 38' E, 6–20 iii 2001, R. Harin’Hala (10 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-04, elev. 10 m, 12° 15' S, 49° 23' E, 6–20 iii 2001, R. Harin’Hala (6 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B- 0 9, elev. 10 m, 12° 15' S, 49° 23' E, 13–16 iii 2001, R. Harin’Hala (5 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-10, elev. 10 m, 12° 15' S, 49° 23' E, 16–31 iii 2001, R. Harin’Hala (8 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-05, elev. 10 m, 12° 15' S, 49° 23' E, 20 iii–7 iv 2001, R. Harin’Hala (18 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-06, elev. 10 m, 12° 15' S, 49° 23' E, 7–22 iv 2001, R. Harin’Hala (13 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-07, elev. 10 m, 12° 15' S, 49° 23' E, 22– 27 iv 2001, R. Harin’Hala (1 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01- 04B-08, elev. 10 m, 12° 15' S, 49° 23' E, 27 iv–13 v 2001, R. Harin’Hala (6 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-11, elev. 10 m, 12° 15' S, 49° 23' E, 31 v–7 vi 2001, R. Harin’Hala (4 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-12, elev. 10 m, 12° 15' S, 49° 23' E, 7–25 vi 2001, R. Harin’Hala (10 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-13, elev. 10 m, 12° 15' S, 49° 23' E, 25 vi–6 vii 2001, R. Harin’Hala (6 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-15, elev. 10 m, 12° 15' S, 49° 23' E, 20–28 vii 2001, R. Harin’Hala (8 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-17, elev. 10 m, 12° 15' S, 49° 23' E, 13–20 viii 2001, R. Harin’Hala (5 CAS); Sakalava Beach, dwarf littoral forest; malaise trap—across sandy trail MA-01-04B-19, elev. 10 m, 12° 15' S, 49° 23' E, 28 viii–12 ix 2001, R. Harin’Hala (2 CAS); Toamasina, 7 km SE of Andasibe National Park head- quarters, malaise trap- in tropical forest, elev. 1050 m, 18° 57' S, 48° 27' E, 23 iii–7 iv 2001, R. Harin’ Hala (MA-01-08A-04) (1 CAS), (MA-01-08A-05) (2 CAS), (MA-01-08A-06) (7 CAS); Botanic garden near entrance to Andasibe National Park, malaise trap—tropical forest, elev. 1025 m, 18° 55' S, 48° 24' E, 23–30 iv 2001, R. Harin’ Hala (MA-01-08B-01) (1 CAS), (MA-01-08B-03) (1 CAS), (MA-01-08B-06) (2 CAS); Botanic garden near entrance to Andasibe National Park, malaise trap—tropical forest, elev. 1025 m, 18° 55' S, 48° 24' E, 8–16 x 2001, M. Irwin, R. Harin'Hala (MA- 01-08B-15) (20 CAS), (MA-01-08B-19) (15 CAS), (MA-01-08B-20) (11 CAS).

Differential Diagnosis. Differentiated from other members of the species group by the smaller size, broader body form (ca. 2.19 x 0.98 mm), and generally darker color. The aedeagus is easily distinguished from that of other members.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.19/0.98; head width 0.56; pronotum 0.56/0.70, PA 0.57, PB 0.63; elytra 1.31/0.98.

Head piceous, pronotum and elytra brown to dark brown, margins of pronotum very slightly lighter than disc; legs brown; maxillary palpi light brown to testaceous, last palpomere not darker.

Head with frons moderately finely densely punctate, interstices weakly shining, ca. 1xpd. Mentum sparsely punctulate, shining; postmentum subrugulose, interstices shining. Genae raised, shining, with posterior ridge.

Pronotum more coarsely and densely punctate than frons, interstices varying from narrow ridges to ca. 1xpd. Pronotum sinuate laterally; anterior margin straight behind eyes, emarginate behind frons; PF1 and PF2 absent; PF3 deep; PF4 shallow.

Elytra weakly arcuate laterally; summit of posterior declivity slightly past midlength; lateral explanate margins moderately wide, not continuing to apices; serial punctures round, and closely spaced, slightly larger than pronotal punctures. Intervals not raised or only very weakly, dull or very weakly shining, ca. 1xpd. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very shallow if any angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/2/1.5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides parallel, apex blunt, apex contiguous with strong midlongitudinal carina of metaventrite, which extends to anterior margin of plaques. Plaques large, roundly raised, wider posteriorly than anteriorly, arcuate, almost contiguous anteriorly and joining anteromedian carina forming inverted Y-shape, located at sides of deep median depression. Metaventrite with longitudinal carina on each side, extended posteriorly from margin of each mesocoxal cavity to ca. midlength of metaventrite. AIS slightly depressed, width at arcuate posterior margin ca. 1.5x P2. Protibia slender, very weakly if at all arcuate, prominent spine-like seta on medial margin slightly past midlength. Mesotibia almost straight, medial margin emarginate over ca. median 1/3 of length, and here bearing 5– 6 short, sharply pointed spines; distal 1/3 slightly thickened. Metatibia slender, slightly arcuate, subapically on medial margin bearing very small and indistinct patch of setae that lie flat on cuticle in dry specimens. Abdominal apex symmetrical; last tergite raised slightly on each side of narrow apicomedian notch.