Brachymetra bernaldi Cordeiro, 2018

Pacheco-Chaves, Bernald, Cordeiro, Isabelle Da Rocha Silva, Moreira, Felipe Ferraz Figueiredo & Springer, Monika, 2018, The water striders (Hemiptera: Heteroptera: Gerridae) of Costa Rica: new species, checklist, and new records, Zootaxa 4471 (3), pp. 493-522 : 494-495

Brachymetra bernaldi Cordeiro sp. nov.

( Figs. 1–9 )

Material examined. COSTA RICA: Heredia — Sarapiquí, La Tirimbina Reserve , stream in La Ceiba Trail , 07.VII.2008, (B. Pacheco): 1 apterous male (holotype, CEIOC 42.001 ), 1 apterous male, 3 apterous females (paratypes, CEIOC 42.002–42.005 ) .

Apterous male (holotype) ( Figs. 1a–c, 3a–b, 5a–9 ): BL 5.60; BW 2.30; HL 0.69; HW 1.46; ANT I 1.34, ANT II 0.70, ANT III 0.78, ANT IV 0.78; EL 0.66; EW 0.44; INT 0.73; PL 2.20; PW 1.35; FORELEG: FEM 2.25, TIB 2.10, TAR I 0.22, TAR II 0.33; MIDLEG: FEM 6.0 0, TIB 5.92, TAR I 1. 0 9, TAR II 0.34; HINDLEG: FEM 6.92, TIB 3,16, TAR I 0.49, TAR II 0.30.

Body yellowish brown to brown, with dark brown setae on dorsum and light setae on venter. Vertex of head brown. Clypeus yellowish brown to orange brown, darker anteriorly. Eye silvery. Margin of antenniferous tubercle and proximal 2/3 of antennomere I brown; remaining of antenna dark brown. Buccula brown. Labrum dark brown. Articles I–II of labium brown; III yellow laterally, orange centrally; IV shining black. Pronotum with longitudinal midline yellowish and margins dark brown. Proacetabulum with rounded brown macula laterally. Mesoacetabulum with irregular brown macula and dark brown margin. Metacetabulum with triangular brown macula in dorsal view. Dorsolateral margin of mesoacetabulum with small row of silvery setae. Legs mainly dark brown. Fore coxa and trochanter yellow; trochanter with dark brown apex in ventral view. Fore femur with anterodorsal 2/3 yellowish and apex blackish. Base of fore tibia dorsally light brown. Middle coxa yellow. Middle trochanter and base of middle femur ventrally yellowish. Hind coxa shining orange brown in dorsal view, ventrally dull yellow. Proepisternum sometimes with short dark brown setae. Prosternum yellow with golden, dark setae. Mesosternum with long dark setae. Abdominal mediotergites II–VI with posterior margins dark brown, VII with posterior 1/2 dark brown. Margins and lateral surface of abdominal laterotergites blackish. Abdominal sterna II–VII with short silvery setae on posterior margins; VIII yellow, brown towards apex, with short dark setae dorsally. Proctiger brown with pale yellow lateral projections. Pygophore yellow, brown towards apex. Paramere yellow.

Body covered by setae, except for mesal margins of pro- and mesoacetabula. Head subtriangular. Eye flattened, oval. Clypeus rectangular with weak lateral notch. Labrum triangular. Antenna covered by short setae; antennomere I widest, followed by II, III –IV subequal in width; I slightly wider on apex; apex of IV acute. Labium reaching mesosternum between fore trochanters; article II with a pair of thin, elongated setae. Patch of medium sized setae ventral to eyes. Pronotum 1.6 times longer than wide, not reaching abdominal tergum I; anterior lobe with small central depression; posterior lobe with almost imperceptible carina; posterior margin rounded. Legs covered by short setae. Fore coxa with few curved setae on lateral surface. Fore trochanter ventrally with two thin basal setae. Fore femur dorsally with few short dark setae at base; ventrally with long setae, conical black setae denser on proximal half, and curved setae on apex. Fore tibia slightly narrowed and bifurcated by an oblique longitudinal cleft on apical region, with few medium sized setae throughout length; mesal apical process discreet. Middle coxa with irregular callosity, with curved setae on mesal and lateral margins. Middle trochanter without thin, long setae. Middle femur with three trichobothria-like setae at base and conical black setae throughout length. Middle tibia with conical black setae up to apex. Hind coxa with inconspicuous callosity, with curved setae dorsally and ventrally. Hind trochanter with a thin, long seta on mesal surface. Hind femur with seven trichobothria-like setae on proximal 1/2, conical black setae throughout length, and curved setae on apex. Hind tibia with conical black setae. Abdominal mediotergite I with posterior margin sinuous; III –V subequal in width; VI slightly wider; VII three times longer than others, concave in lateral view. Abdominal sterna II–VI subequal in width; VII subquadrate, with posterior margin concave; posterior margin of VIII curved in lateral view ( Fig. 5c ). Proctiger without hook on lateral projection ( Fig. 7 ); lateral margin with central tumescence; posterior margin truncated; basolateral process developed, directed posteriorly. Pygophore emarginated on apex ( Fig. 6b ). Paramere narrow, notched on median region; apex acute ( Figs. 8a–b ). Dorsal sclerite of phallus well-developed ( Fig. 9 ); apex large; width at apex approximately 4 times central width; ventral sclerite bifurcated and connected to the dorsal one.

Apterous female (paratype) ( Figs. 2a–c, 4a–b ): BL 6.10; BW 2.45; HL 0.70; HW 1.46; ANT I 1.35; ANT II 0.63, ANT III 0.75, ANT IV 0.75; EL 0.68; EW 0.44; INT 0.65; PL 2.35; PW 1.45; FORELEG: FEM 2.05; TIB 1.95; TAR I 0.22; TAR II 0.31; MIDLEG: FEM 5.62; TIB 5.61; TAR I 1. 0 7, TAR II 0.28; HINDLEG: FEM 6.38; TIB 2.76; TAR I 0.50; TAR II 0.27.

Similar to the male, except: silvery setae absent from lateral surface of acetabula, abdominal mediotergite VII trapezoidal with concave posterior margin, and mediotergite VIII with weak central notch on posterior margin.

Etymology: This new species is named in honor of its collector and colleague Bernald Pacheco-Chaves.

Comments: Brachymetra is a small and strictly Neotropical genus represented by four species in Central America: B. albinervus (Amyot & Serville, 1843) , B. shawi Hungerford & Matsuda, 1957 , B. unca Shaw, 1933 , and B. bernaldi Cordeiro , sp. nov. Among these, B. unca is easily recognized by antennomere I longer than II and III together, and the pronotum with the longitudinal midline dark brown, whereas B. shawi can be identified by the pronotum with an acute apex, reaching to abdominal mediotergite I in apterous forms and extending well beyond the suture between meso- and metanota in alate individuals, and the fore femur without conical black setae ventrally.

The new species is more similar to B. albinervus , with which it shares the general color and body proportions. However, it differs from it by the weak median carina of the pronotum in alate individuals; and males with abdominal mediotergite I with weak lateral notches, mediotergite VII quadrate, abdominal segment VIII in natural position almost entirely inserted into the abdominal cavity, and paramere narrow with apex acute. In B. albinervus , the median carina of the pronotum and the lateral notches of abdominal tergum I are stronger; and males with abdominal mediotergite VII trapezoidal, abdominal segment VIII has at least half of its length exposed, and the paramere is wider with apex obtuse. All species of Brachymetra will be included in a forthcoming key and revision of the genus.

Figures

FIGURES 1–9. Brachymetra bernaldi Cordeiro, sp. nov. 1a. Male, dorsal view. 1b. Male, ventral view. 1c. Male, lateral view. 2a. Female, dorsal view. 2b. Female, ventral view. 2c. Female, lateral view. 3a. Male, apex of abdomen, dorsal view. 3b. Male, apex of abdomen, ventral view. 4a. Female, apex of abdomen, dorsal view. 4b. Female, apex of abdomen, ventral view. 5a. Male, abdominal segment VIII, dorsal view. 5b. Male, abdominal segment VIII, ventral view. 5c. Male, abdominal segment VIII, lateral view. 6a. Male, pygophore, lateral view. 6b. Male, pygophore, detail of apex, caudal view. 7. Male, proctiger, dorsal view. 8a. Paramere, caudal view. 8b. Paramere, lateral view. 9. Sclerites of phallus, lateral view (DE: dorsal sclerite, VE: ventral sclerite).