Setostylus bellulus (Williston)

Huerta, Heron & Fitzgerald, Scott J., 2020, A new species of Setostylus Matile and new records of Setostylus bellulus (Williston) (Diptera: Keroplatidae), Zootaxa 4722 (1), pp. 84-90 : 85-89

Setostylus bellulus (Williston)

Ceroplatus bellulus Williston, 1900: 219 . Mexico (Tabasco, type locality Teapa, male; Figs. head, habitus).

Placoceratias fuscithorax Enderlein, 1910: 152 . Brazil (Santa Catarina).

Ceroplatus (Euceroplatus) bellulus (Williston) , Fisher, 1941: 286 (list of species), 293 (subgeneric placement).

Euceroplatus bellulus (Williston) , Papavero, 1978 (catalogue of Diptera of the Americas south of the United States, distribution).

Setostylus bellulus: Matile, 1990: 332–334 (synonymy; key to Neotropical species; male genitalia Figs. 923, 932); Evenhuis, 2006: 65 (catalog of the Keroplatidae of the world, distribution).

Distribution: Matile (1990) records the distribution of this species as “ Brazil ” and “Central America”, yet S. bel- lulus is at least also present in Mexico, as it was originally described from Tabasco, Mexico. The Brazilian record is from Santa Catarina ( Enderlein, 1910: 154). An additional record from North Carolina, USA ( Evenhuis, 2006) warrants further scrutiny as Cerotelion johannseni Fisher (described from North Carolina) has been historically misidentified as Ceroplatus bellulus (see Fisher, 1940 and Laffoon, 1965: 200 “ bellulus , authors, not Williston”). Recent study of eastern Nearctic fungus gnats (by SF) has not resulted in any specimens of Setostylus , but has included 11 specimens of C. johannseni . Until a Nearctic record can be verified, these authors deem it better to consider this distribution record an error based on misidentification.

New Records. COSTA RICA: Puntarenas, Manuel Antonio N.P., 23–28 Aug. 1986, ss coastal rainforest, L. Masner (1 male, CNCI) ; GUATEMALA: Guatemala: Puerta Parada, 1850 m alt., Col. J.C. Schuster, 15–21 Aug. 2015 (2 males, SFC) ; same except 17–21 Aug. 2013 (2 males, SFC) ; same except 22–28 Aug. 2015 (1 male, SFC) ; same except 3–10 Aug. 2013 (1 male, SFC) ; same except 18–26 July 2015 (1 male, SFC) ; same except 23–30 May 2015 (1 male, SFC) ; same except 5–12 Oct. 2013 (1 male, SFC) ; same except 21–28 Sept. 2013 (1 male, SFC) ; same except 26 Jan.–2 Feb. 2013 (1 male, UVGC) ; same except Bosques cipres, 1–8 Dec. 2012 (1 male, SFC) & 15–22 Dec. 2012 (1 male, SFC) ; same except Casa Jack, 5–12 Jan. 2013, 14.556630, -90.463362 (1 male, SFC) .

Setostylus xoxo spec. nov.

( Figs. 1–4 )

Type-material. HOLOTYPE. Male, MEXICO, Morelos, Locality Jojutla, cerca del Río Apatlaco , 10-Oct-2010, red aérea, [GPS: 18° 36´57´´ N, 99° 11´00´´ W]. Leg. Marquez-Monroy, M.A. V. Permanent microscope slide in Euparal ( CAIM) . PARATYPE. Male, USA: Arizona: Cochise Co., Huachuca Mts. , 0.8 road miles SW of Reef, 15–24 July 2018, 31.4238°, -110.2991°, W.B. Warner, V-flight-intercept trap ( SFC) .

Diagnosis. Setostylus xoxo spec. nov. can be distinguished from all New World congeners by the posterior edge of male tergite 9 with a median emargination ( Figs. 3C, E ), and male terminalia as Figs. 3B, D . The male genitalia are most similar to Setostylus pictipennis Matile and S. bellulus (Williston) , and in addition to the difference in male tergite 9, the terminalia also differ from these species in the arrangement, number and size of the marginal spines of the posterior margin of the gonocoxites. S. xoxo also differs from S. pictipennis by the fore tibial spur twice as long as the apical width of the fore tibia rather than subequal to its width.

Description of Male: Body length 6.0 mm.

Head. Rounded, wider than long. Eyes dark brown, dichoptic, facets of similar width, length of interommatidial setae longer than facet width. Three ocelli present, ocellar triangle dark brown, middle ocellus smaller, lateral ocelli of similar size, distance between ocelli similar to ocellus diameter. Vertex with dense dark setae; frons and face bare, frontal furrow marked by a line. Clypeus with a patch about 25 setae. Mouthparts reduced; labella small. Maxillary palpus with two articulated segments. First, basal, segment short, rounded with several setae; distal segment ovoid with several lateral black setae. Antenna ( Fig. 1A ) dark brown, except base of flagellomere 1 pale; length 1.05 mm (scape, pedicel and flagellomeres), with 14 flagellomeres. Scape and pedicel compressed laterally. Flagellomeres 1–14 strongly compressed laterally; flagellomere 14 rounded apically. Flagellomeres covered with short fine sensilla-like trichia, dorsal macro-setae longer than ventral setae present on each flagellomere.

Thorax. ( Fig. 1B ). Scutum with a wide pale area contrasted by dark brown, longitudinal stripes, converging posteriorly to form a V, anterior and lateral areas dark brown; transverse suture absent; notopleural and supra–alar areas with bristles; scutellum dark brown, ventrally pale; mediotergite dark brown. Pleural sclerites dark brown. Antepronotum and proepisternum with setae. Anepisternum with a patch of approximately 30 small setae; laterotergite dark brown. Prosternum setose.

Legs ( Figs. 1 C–E). Fore coxa pale brown; mid and hind coxae with the basal half pale, distal half dark brown. Fore femur almost completely pale brown, except a small dark brown, ventral spot at the base; mid femur similar to the fore femur, but with the ventral spot more extended; hind femur pale brown, except basally dark brown. Tibiae pale brown to brown, hind tibia with apex dark brown. Tarsi uniformly dark brown, covered with fine setae and trichia; tibial spurs 1:2:2. Fore tibial spur about twice as long as the apical width of the fore tibia. All tibiae and tarsi densely covered with regular rows of microtrichia and mid and hind tibia with some ventral setae near apices. Apical comb of setae presents on inner face of tibiae. Tarsal claws short, with basal teeth.

Wing ( Fig. 2 ). Length, 2.98 mm; width, 1.32 mm. Membrane covered with abundant microtrichia, without macrotrichia. Hyaline with only hint of brown infuscation along costal edge beyond R 2+3 to more extensive brown areas present anteriorly and at apex of wing, medially with faint hyaline area. R 1 and R 4+5 with dark macrotrichia arranged along the veins. Costa reaching tip of wing, extending beyond tip of R 4+5. Sc elongate, extending more than 1/3 the length of the wing, ending in C; R 1 elongate, straight, extending 3/4 of the wing length, ending in C; R 2+3, short, inclined, ending in C; R 4+5 ending before the apex of C; Rs longer than R+M fus. Stem of medial fork short, arising beyond the R+M fus; R+M fus short, linear, slightly longer than the stem of medial fork; M 1 and M 2 reaching the wing margin, M 4 ends at wing margin at same level of apex of R 2+3; CuA slightly curved, ending beyond the apex of Sc; m-cu crossvein short, inclined. CuP slightly curved at the base, ending at same level as apex of Sc. Halteres with knob dark brown.

Abdomen. ( Fig. 3A ). Length 4.0 mm. Brown. Abdominal segments 1–2 brown; segment 3 with basolateral area pale; segment 4–5 with basal band pale, more extended in segment 4; segment 6–7 dark brown.

Terminalia ( Figs. 3 B–E). Dark brown. Length 0.32 mm, wide 0.35 mm. Gonocoxites setose with anterior margin emarginated and posterior margin straight with an apical row of about 25–32 small, thick, black spines and a median, longitudinal, narrow, desclerotized strip (pale ventral strip); gonostylus basally wide and setose, bearing a group of 6–8 large black setae medially, tapering apically to a thin, pale, filament, and terminating with a small apical seta. Gonostylus dorsomedially with a small, semi-transparent, posterodorsally-projecting tooth (best seen in lateral view). Aedeagal complex simple, T-shaped, extending to posterior margin of gonocoxite; paramere horseshoe-shaped, extending to the base of cerci, basally connected with gonocoxal apodeme. Tergite 9 much longer than wide, setose, anterior margin with a U-shaped emargination, posterior margin emarginated medially with a notch. Cercus setose, rounded.

Female. Unknown.

Distribution. Morelos, Mexico and southern Arizona, USA. ( Fig. 4 ).

Etymology. The specific epithet “xoxo” is a place-name abbreviation derived from the type locality Jojotla, which is a Spanish euphony of the Nahuatl place-name Xoxoutla.

Remarks. Based on the phylogenetic work by Matile (1990), S. xoxo fits best in the Neotropical S. pictipennis species-group based on the long narrow form of the gonostylus and the absence of anterior macrosetae on tibia III; this group includes S. bellulus , S. pictipennis , S. bifidus , S. singularis and S. xoxo ; these species can be differentiated with the previous key.

Figures

FIGURE 1. Setostylus xoxo spec. nov. Holotype male. A. Antenna, lateral view (dorsal edge on right). B. Thorax, dorsal view. C–E. Legs, lateral view. C. Fore leg. D. Mid leg. E. Hind leg. Abbreviations: cx = coxa; fe = femur; flgm 1 = first flagellomere; hlt = halter; pe = pedicel; tb = tibia; tb spr = tibial spur; tr = trochanter; tsm 1 = tarsomere 1; scp = scape. Scale: A= 0.1 mm; B–E= 0.5 mm.

FIGURE 2. Setostylus xoxo spec. nov. Holotype male. Wing, dorsal view. Abbreviations: C = costal vein; CuA = anterior branch of cubital veins; CuP = posterior branch of cubital veins; h = humeral crossvein; m-cu = medial cubital crossvein; R+M fus = radial + medial fusion; M1, M2 and M4 = branches of medial vein; R1, R2+3, R4+5 = radial veins; Rs = radial sector; Sc = subcostal vein. Scale= 0.5 mm.

FIGURE 3. Setostylus xoxo spec. nov. Holotype male. A. Abdomen, ventral view. B, D. Male genitalia, ventral view. C, E. Tergite 9, dorsal view (posterior edge at top in the Fig. E). Scales:A = 0.5 mm; B–C = 0.1 mm; D–E = 0.16 mm. Abbreviations: Ae com= Aedeagal complex; cer = cerci; gs = gonostylus; gx = gonocoxites; pa = paramere.

FIGURE 4. Setostylus xoxo spec. nov. Distribution (solid circles) in states of Morelos, Mexico and Arizona, USA.