Macrostemum nigralatum

Suwannarat, Nannaphat, Malicky, Hans & Laudee, Pongsak, 2018, Two new species of Caddisflies (Trichoptera: Insecta) from Lower-Hill Evergreen Forests of Southern Thailand, Zootaxa 4524 (4), pp. 496-500: 497

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Macrostemum nigralatum

n. sp.

Macrostemum nigralatum  n. sp. Laudee and Malicky

Figs. 1–6View FIGURES 1–6

Type material. Holotype male (PSUNHM). Thailand: Surat Thani Province, Tai Rom Yen National Park, Khao Nong, Lam Phun stream 8°50′33″N, 99°30′27″E, ca. 960 m a.s.l., 20 March 2017, leg. Pongsak Laudee.GoogleMaps 

Paratypes: Same data as holotype, 2 males (PSUNHM); Thailand: Surat Thani Province, Tai Rom Yen National Park, Pha San Yen stream, 12°04′52″N, 99°37′43″E, ca. 1,100 m a.s.l., 12 February 2017, leg. Pongsak Laudee, 2 males (PSUNHM)GoogleMaps  .

Etymology. The species epithet comes from the Latin adjectives niger, - ra, - rum, and alatus, -a, -um, meaning “black” and “winged,” in reference to the black forewings of this species.

Description. Length of each male forewing 12.0 mm (n = 5); specimens in alcohol with head, thorax, and forewings black ( Fig. 6View FIGURES 1–6).

Male genitalia ( Figures 1–5View FIGURES 1–6). In dorsal view ( Fig. 2View FIGURES 1–6), segment IX rectangular with subrectangular incision for half of its length anteriorly; lateral lobes of segment IX subrectangular, truncate apically with long setae; in lateral view ( Fig. 1View FIGURES 1–6), segment IX short with truncated lateral lobes, convex basodorsally, truncated apicoventrally, apicolateral margins with numerous setae; in ventral view ( Fig. 3View FIGURES 1–6), segment IX subrectangular with anterolateral lobes and V-shaped incision posteromesally. Segment X in dorsal view ( Fig. 2View FIGURES 1–6), long, with deep V-shaped incision apically forming 2 oval lobes; in lateral view ( Fig. 1View FIGURES 1–6) with somewhat triangular, round apically. Inferior appendages slender, long; each with basal segment slender, about 1.5 times as long as apical segment; apical segment slender with short setae apically, rounded apex; curving slightly mesad in ventral view ( Fig. 3View FIGURES 1–6). Phallus axe-shaped, expanded basally, bulb-like subapically, pointed apically in lateral view ( Fig. 4View FIGURES 1–6); long, hourglassshaped in ventral view ( Fig. 5View FIGURES 1–6).

Diagnosis. The genitalia of the new species are similar to those of the well-known and widespread M. fastosum ( Walker 1852)  found in Southeast Asia: Bali, Java, Sumatra, Laos, Thailand, and Vietnam ( Malicky 2010). They can separate by characteristics of the dorsal view of segment X. In Macrostemum nigralatum  n. sp., segment X is rectangular with a deep V-shaped incision apically forming 2 oval lobes, rounded apically. The dorsal view of M. fastosum  segment X has a V-shaped incision for 1/2 of its length, with apical lobes bent outward apically. They can be separated very easily by the color of the forewings, M. fastosum  has yellow wings with dark markings, but the wings are black without marking in the new species ( Fig. 6View FIGURES 1–6). The Brazilian species M. nigrum  Franca et al. 2013 also has the forewings entirely black, but the male genitalia are different.