Ablabesmyia adamantis, Dantas & Hamada, 2019

Dantas, Galileu P. S. & Hamada, Neusa, 2019, Three new neotropical species of Ablabesmyia Johannsen, 1905 (Diptera: Chironomidae), Zootaxa 4567 (1), pp. 111-129 : 122-128

Ablabesmyia adamantis sp. n.

Type material. Holotype: male with pupal and larval exuviae, BRAZIL, Roraima, Amajari municipality, Serra do Tepequém , 03°46'43.90"N / 61°45'29.30"W, 06.vii.2016, G.P.S. Dantas ( INPA).

Diagnostic characters. Adult male: tergite IX with 1 dorsal seta on each side; dorsal lobe short, without apical brush; aedeagal blades striated, slightly curved at apex; forefemur with 2 bands, fore tibia with 4 bands; mid femur with 2 bands, mid tibia with 4 bands; hind femur with 2 band, hind tibia with 3 bands. Pupae: cephalothorax and wing sheath with light spots; thoracic horn lumen with a poorly defined circular pattern, aeropyle with a sinuous tube; thoracic comb with 16 teeth; anal lobe outer margins straight and convergent beyond the second macroseta, inner margin straight and parallel sided, abruptly tapered at apex; male genital sac extending beyond the insertion of the second anal macrosetae, inner margins parallel sided, apex rounded. Larva: postoccipital margin with small anterior projections; palpiger markedly elongated, about 50 µm long; posterior parapods with two darkbrown claws.

Etymology: From Latim adamas = diamond, a reference to the type locality, which was a diamond exploration area in the past.

Adult male (n = 1). Total length 3.04 mm. Wing length 1.64 mm. Total length/wing length 1.85. Wing length/ length of front femur 2.36.

Coloration. Thorax brown ( Fig. 8B ). Wing with patterns of brown spots as in figure 8C. Forefemur with 2 bands, fore tibia with 4 bands. Mid femur with 2 bands, mid tibia with 4 bands. Hind femur with 2 bands, the fist is incomplete, hind tibia with 3 bands. Abdomen ( Fig. 9A ) pale yellow with dark markings; tergites II–V with 3 dark brown spots, 1 anteromedially and 2 anterolaterally, but anteromedial spots occasionally absent; tergites VI–VII mostly dark brown; tergite VIII mostly light brown; hypopygium with gonocoxite apex and gonostylus base lightbrown.

Head ( Fig. 8A ). Antennal flagellum 1065 µm long, apical flagellomere 111 µm long, 19 µm wide, pre-apical seta 34 µm long, pedicel 145 µm wide, with 5 setae. AR 1.96. Eyes bare; dorsomedial extension well developed, 128 µm long, 57 µm wide, medially separated by distance of 115 µm. Temporal setae 42, multiserial anteriorly and uniserial posteriorly. Clypeus 109 µm long, 85 µm maximum width, with 25 setae. Cibarial pump with anterior margin strongly concave, 272 µm long, orifice located 107 µm from apex. Tentorium 164 µm long. Palpomeres 1– 5 (µm): 43; 85; 128; 113; 205. Third palpomere with 1 campaniform sensilla.

Thorax ( Fig. 8B ). Antepronotum with 22 lateral setae. Acrostichals about 60, biserial, diverging posteriorly; dorsocentrals 31, multiserial anteriorly and uniserial posteriorly; prealars 23, multiserial; supraalar 1. It was not possible to count the scutellars due to the thorax position on the slide.

Wing ( Fig. 8C ). Width 0.47 mm. Costal vein 1.57 mm long, not produced beyond apex of R 4+5, ending before the apex of M 1+2. Brachiolum with 3 setae. Squama with 33 setae. Anal lobe well developed. VR 0.81. WW 0.29.

Legs ( Figs. 8 D–F Legs ( Figs. 1 D–F). Foretibia 48 µm wide at apex, with one apical spur 51 µm long, bearing 10 lateral teeth. Mid tibia 45 µm wide at apex, with two apical spurs, 40 and 59 µm long, bearing 4 and 8 lateral teeth, respectively. Hind tibia 52 µm wide at apex, with two apical spurs, 47 and 61 µm long; tibial comb indistinct with 4 bristles. Lengths and proportions of leg segments as in Table 4.

Hypopygium ( Figs. 9 B–E): Tergite IX with 1 dorsal seta on each side; anal point completely covering the aedeagal complex; phallapodeme 40 µm long; transversal sternapodeme robust, anteriorly projected, with anterior margin blunted ( Fig. 9D ), 37 µm long; gonocoxite 140 µm long; gonostylus 150 µm long, with 4 apical teeth and tapered megaseta; HR 0.93; HV 2.03. Aedeagal complex with striated blade, 42 µm long, slightly curved at apex and widened at base; dorsal lobe small, 8 µm long and 5 µm wide, without apical brush ( Figs. 9 B–C, E); lateral lobe filamentous; lateral filaments well developed; basidorsal lobe reduced.

Female imago. Unknown.

Pupa (n = 1). Total length 3.93 mm (abdomen and thorax of male).

Coloration. Exuvia light-brown ( Fig. 10C ). Wing sheath brown along margin and veins, with dark spots ( Fig. 10B ); thoracic horn dark-brow. All abdominal tergites brown, each with anterior darker patches.

Cephalothorax. Dorsal surface slightly roughened. Frontal apotome apically truncated. Wing sheath smooth ( Fig. 10B ), 1168 µm long, 421 µm maximum width. Thoracic horn ( Fig. 10A ) 370 µm long, 170 µm wide, with a poorly defined circular pattern, spines present on the external membrane; apical nipple with aeropyle tube sinuous. Thoracic comb with 16 teeth.

Abdomen ( Fig. 10C ). Tergite I with shagreen of spinules in transversal rows, with distinct, elongate scar, 177 µm long; TII–VI with extensive shagreen of spinules in arc; TVIII–IX with extensive shagreen of scattered spinules. Segment VII with 4 LS setae. Segment VIII with 5 lateral filaments, distal margin of segment straight. Anal lobe ( Fig. 10D ) 345 µm long, 317 µm wide at the base, with 2 lateral macrosetae; outer margins straight anteriorly and slightly concave beyond the second macroseta, with 10 small spines; inner margin straight and parallel sided, abruptly tapered at apex, without spines. Male genital sac 287 µm long, 222 µm wide at the base, extending beyond the insertion of the second anal macrosetae. GS/AL 0.83.

Larva (n = 1). Coloration. Head capsule yellow without circular brown spot, postoccipital margin dark-brown; apex of mandible dark-brown; ligula brown, with teeth dark-brown; paraligula brown; claws of posterior parapods yellow, but two are dark-brown.

Head ( Fig. 11A ). Head capsule longish-oval; cephalic index about 0.62. VP closer to S10 than to S9, located posterolateral to S9, mesial to S10; lines S9–VP and S10–VP making obtuse angle ( Fig. 11B ). Postoccipital margin with small anterior projections ( Fig. 11C ).

Antenna. Total length 528 µm, A 1 433 µm long, 22 µm wide at base; ring organ placed 231 µm from base, A 2 89 µm long. AR 4.56.

Maxilla. Basal segment of maxillary palp ( Fig. 11D ) subdivided into 2 parts; basal part (P 1) 30 µm long and 12 µm wide, apical part (P 2) 48 µm long and 8 µm wide; ring organ placed 28 µm from base; membranous palpiger markedly elongated, 50 µm long and 14 µm wide. A 1 /P 1 14.4; A 2 /P 1 2.97.

Mandible ( Fig. 11E ). Length 146 µm; with 3 lateral setae present; ring organ placed 28 µm from base. Apical tooth 51 µm long, mola projection large, blunt-ended and apically-directed, 11 µm long; inner tooth large, bluntly rounded at apex, partly overlying, but not projecting beyond margin of seta subdentalis. Seta subdentalis 37 µm long. A 1 /MD 2.97.

Mentum and M appendage. Dorsomental teeth reduced, M appendage rounded apically; with pseudoradula 125 µm long, 14 µm wide, granulated uniformly.

Hypopharyngeal complex ( Fig. 11F ). Ligula 99 µm long, 57, 39 and 64 µm wide at toothed, middle and basal widths, respectively, granulated at base, with 5 teeth; row of teeth concave, point of inner teeth slightly directed outwardly; granulated at base. Paraligula bifid and robust, 46 µm long and 13 µm wide. Pecten hypopharyngis with about 25 teeth.

Body. Without fringe of swim-setae. Anterior parapods with simple claws. Procercus 112 µm long, 32 µm wide at base, with 7 anal setae, 602 µm long. Supra-anal setae 356 µm long. Sub-basal setae of posterior parapod damaged. Anal tubules not measurable. Posterior parapods with hooklets and about 14 simple claws ( Fig. 11G ), some are slightly serrated on the inner margin.

Taxonomic remarks. Ablabemsyia adamantis sp. n. is closer related to A. arquata Neubern , the two species have femur with similar coloration pattern and a small and truncated dorsal lobe. However, the new species can be recognized by having 4, 4, 3 bands on the fore, mid and hind tibiae respectively, TIX with one seta on each side and transversal sternapodeme robust. In contrast, A. arquata has 4, 3, 3 bands on the fore, mid and hind tibiae respectively, two setae on each side of TIX and a relatively thin transversal sternapodeme. Furthermore, A. arquata has the aedeagal blades strongly arched, while in A. adamantis sp. n. they are only slightly curved at apex.

The pupa of the new species resembles that of A. reissi by the wing sheath with spots, genital sac ending beyond the insertion of the second anal macrosetae and outer side of thoracic horn and of anal lobe with spines. However, in A. adamantis sp. n. the thoracic horn has a poorly defined circular pattern and thoracic comb is composed of 16 teeth, while in A. reissi the thoracic horn has a hexagonal pattern and thoracic comb is composed of 8–9 teeth.

The larva of A. adamantis sp. n. seems close related with that of A. gessnerae Neubern by the head capsule without spots, postoccipital margin with projections, procercus with 7 anal setae and posterior parapods with 2 brown claws. The two species differ each other in the relative position of the ventral setae: in A. adamantis sp. n. S10 is mesial to VP, which is closer to S10 than to S9, whereas in A. gessnerae S10 is anterior to VP, which is closer to S9 than to S10.

Notes on biology. The larva of Ablabesmyia adamantis sp. n. was collected in a first order stream, associated with decidous leaves accumulated in the bottom, with 0.95 m wide, 0.09 m deep and negligible flow, at about 600 m above s.l. This water course is characterized by acidic black water (4.75), low conductivity (1.30 mS/cm), high concentration of dissolved oxygen (6.76 mg /L) and low temperature variation (about 24 °C). The opening of the canopy was small and the dominant substrate types in the stream beds were sand, thick and fine litter.

Distribution. This species is known only from the type locality in the Serra do Tepequém, Roraima State, Brazil ( Fig. 5 )

Figures

FIGURE 1. Ablabesmyia akemiae sp. n., adult male. (A) Head. (B) Thorax, lateral view. (C) Wing. (D) Front femur and tibia. (E) Mid femur and tibia. (D) Hind femur and tibia.

FIGURE 5. Distribution map of A. akemiae sp. n., A. monticola sp. n. and A. adamantis sp. n.

FIGURE 8. Ablabesmyia adamantis sp. n., adult male. (A) Head. (B) Thorax. (C) Wing. (D) Fore femur and tibia. (E) Mid femur and tibia. (D) Hind femur and tibia.

FIGURE 9. Ablabesmyia adamantis sp. n., adult male. (A) Abdomen. (B–C) Hypopygium. (C) Transversal sternapodeme. (D) Aedeagal complex, dorsal view.

FIGURE 10. Ablabesmyia adamantis sp. n., pupa. (A) Thoracic horn. (B) Wing sheath. (C) Abdomen. (D) Anal lobe.

FIGURE 11. Ablabesmyia adamantis sp. n., larva. (A) Head. (B) Ventral cephalic setae. (C) Postoccipital margin. (D) Maxillary palp. (E) Mandible. (F) Ligula and paraligula. (G) Posterior parapods.