Macrostemum fenestratum Albarda, 1887

Uy, Christine Jewel C., Malicky, Hans & Bae, Yeon Jae, 2018, Review of the filter-feeding caddisfly subfamily Macronematinae (Trichoptera: Hydropsychidae) in tropical Southeast Asia, Raffles Bulletin of Zoology 66, pp. 664-703 : 677

Macrostemum fenestratum Albarda, 1887

( Figs. 95–106 )

Macrostemum fenestratum Albarda, 1887: 18 [Holotype female; Indonesia; RMNH].

Macronema similior Banks, 1931a: 396 [Holotype male; Malaysia; MCZ; synonymised by Malicky, 2009: 47].

Macronema spectabilis Banks, 1931a: 395 [Holotype male; Malaysia; MCZ; synonymised by Malicky, 2013: 47].

Macronema splendens Banks, 1931b: 421 [Holotype male; Malaysia; MCZ; synonymised by Malicky, 2009: 47; Malicky, 2013: 47].

Diagnosis. Male. Antennae 23 mm in length. Head with dark brown stripe running from ventral part of head beside eye up to dorsal part except middle part in dorsal view. Antennal flagellum dark brown in first few segments, and lighter throughout. Forewing 8 mm and hind wing 6 mm in length. Mesoscutum and mesoscutellum without evident markings. Tibial spurs 2.4.4.

Male genitalia. Inferior appendages two-segmented. Phallus with spine-like structure at anterior portion of apex ( Fig. 105 ). In dorsal view, spine-like structure very evident and sharply pointed ( Fig. 106 ). Segment X divided medially with wide separation and with broad apex ( Figs. 103, 104 ).

Female. Antennae 23 mm in length. Antennal flagellum dark brown in first few segments, and lighter throughout with head markings same as males. Forewing 8 mm and hind wing 6 mm in length. Mesoscutum and mesoscutellum without evident markings. Tibial spurs 2.4.4.

Material examined. Thailand: 19 males, 11 females, Phuket, Tonesai waterfall, coll. P. Chantaramongkol, 1 March 1990 (HMPC) ; Indonesia: 16 males, 12 females, North Sumatra, Huta Padang, coll. H. Malicky, 8 February 1991 (HMPC) ; 1 male, East Kalimantan, Seturan River , coll. P. Derleth, 10 August 2000 (HMPC) .

Distribution. Borneo, Cambodia, Java, Laos, Malaysia (Perak, Pahan, Johor), Sumatra, Thailand, Vietnam.

Remarks. This species exhibited many variations in wing pattern ( Figs. 95–101 ). The segment X of some specimens also varied, when viewed dorsally ( Figs. 103, 104 ) but consistently with narrowing apex in lateral view ( Fig. 102 ).

Figures

Figs. 95–111. Macrostemum fenestratum. 95–101, right forewing variants; Male genitalia: 102, lateral; 103–104, segment X variants dorsal; 105, phallus lateral; 106, phallus tip. Macrostemum floridum. 107, right forewing; Male genitalia: 108, lateral; 109, segment X dorsal; 110, phallus lateral; 111, phallus tip. Scale: 95–101, 107 = 2 mm; 102–106, 108–111 = 0.02 mm.