Metapelopia peruensis, Dantas, Galileu P. S., Hamada, Neusa & Huamantinco Araujo, Ana A., 2016

Dantas, Galileu P. S., Hamada, Neusa & Huamantinco Araujo, Ana A., 2016, A new species of Metapelopia Silva, Oliveira & Trivinho-Strixino (Diptera: Chironomidae) from Peru, Zootaxa 4137 (1), pp. 49-60 : 50-60

Metapelopia peruensis sp. n.

Type material. Holotype male with pupal and larval exuviae, PERU: Departamento Lima, Provincia Cañete, Distrito de Zuñiga, Rio Cañete, 12°50'27.40" S 76°00'03.10" W, 22.viii.2014, leg. N. Hamada, M. Bobadilla, R.L. Ferreira-Keppler & J.M.C. Nascimento (MHN-UNMSM). Paratypes, 2 pupae with pharate males; 1 female with pupal exuvia; 3 larvae; all with the same data as holotype, except ( INPA).

Etymology. The species is named after the type locality, Peru.

Diagnostic character. Male - abdomen with TI pale, TII–III only with a small medial brown spot and TVIII with two anteromedial large brown spots; femora with a preapical brown ring; preepisternum with 5–6 setae. Pupa - plastron plate large and oval-shaped; T VII with 4 LS setae, distributed along the 2/3 distal of the segment. Larva - muscle attachment elongated, 63–75 µm long; VP posteromedial to S9 and posterior to S10; all posterior parapod claws pale yellow.

Description. Adult male (n=1–3).Total length 4.60 mm. Wing length 2.63 mm. Total length/wing length 1.76. Wing length/length of profemur 2.23.

Coloration: Head, clypeus and maxillary palp brown ( Fig. 1 A); antenna brown, most bristles pale brown; bristles placed at the base of the thirteenth flagellomere, dark brown. Thorax with general coloration brown, as in Figure 1 B; medial and lateral vittae, median anepisternum II, posterior anepisternum II, preepisternum and postnotum dark brown; antepronotum and scutellum pale ( Figs. 1 B, 1E). Wing membrane transparent, with spots and covered with macrotrichia, as in Figure 1 D. Legs: femur with a pre-apical brown band; tibia with a basal and an apical brown band; ta1–ta4 with an apical brown band, ta5 pale. Abdomen as in Figure 1 E: TI pale; TII–III with a medial brown spot; TIV–VII with medial and anterolateral brown spots; TVIII two median large brown spots; TIX and hypopygium pale.

Head ( Fig. 1 A). AR 1.77. Antenna with 14 flagellomeres; thirteenth flagellomere 715 µm long. Apical flagellomere 106 µm long; 33 µm wide at base; with a subapical setae 50 µm long. Eyes with small fine setae, restricted to internal margin; dorsomedial extension well developed, 128 µm long, 86 µm wide, medially separated by 127 µm. Temporal setae 23–25, biserial anteriorly and uniserial posteriorly. Clypeus 163 µm long, 128 µm wide, with 38 setae. Cibarial pump with anterior margin concave, 295 µm long and with orifice 80 from apex. Tentorium 200 µm long. Palpomere lengths (1–5 in µm): 82; 151; 156; 230; 337.

Thorax ( Fig. 1 B). Scutal tubercle absent; a strong medial scar present. Acrostichals uncountable; dorsocentrals 33–38, multiserial anteriorly, biserial medially and uniserial posteriorly; prealars 22–23; supraalar 3. Antepronotum with 6–7 lateral setae, tubercle present. Scutellum covered with setae of varying sizes. Preepisternals 5–6.

Wing ( Fig. 1 D). Width 0.75 mm. Membrane with covered with macrotrichia; Costa 2.38 mm long, not produced beyond apex of R4+5,ending between M1+2 and M3+4. MCu proximal to the RM. Brachiolum with 3 setae. Squama with 45 setae, bisserial near the base. Anal lobe well-developed. VR 0.94. WW 0.29.

Legs. Fore leg: tibia with 4 robust preapical bristles, 150 µm long; with an apical, pectinate spur, 53 µm long, with 9 lateral teeth and 1 elongate, curved apical tooth; width at apex of tibia 70 µm. Mid leg: tibia with 2 apical, pectinate spurs, 62 µm long; one with 11 lateral teeth and 1 elongate, curved apical tooth; other with 8 lateral teeth and 1 apical tooth; width at apex of tibia 67 µm. Hind leg: tibia with two apical, pectinate spurs, 54 and 84 µm long, longest spur with 3 lateral teeth and 1 elongate, curved apical tooth, shortest spur with 8 lateral teeth and 1curved apical tooth; width at apex of tibia 78 µm. Tibial comb on hind leg with 6 bristles, the lateral longer than the medial ones. All legs with slender, hook-shaped claws. Pulvilli well developed. Lengths (in µm) and proportions of leg segments as in Table 1 .

Hypopygium ( Figs. 1 C, 2A–B). Tergite IX rounded, with 10 posterior setae. Anal point rounded. Phallapodeme slender, 85 µm long. Sternapodeme with triangular anterior process. Gonocoxite robust, 210 µm long, 107 µm wide; with an internal setose volsella at the base, as in figure 2B, 60 µm long. Gonostylus curved, 150 µm long; megaseta 14 µm long. HR 1.40; HV 3.07.

Adult female (n=1). Total length 4.68 mm. Wing length 2.74 mm. Total length/ wing length 1.71. Wing length/ length of profemur 2.22.

Coloration. Head, clypeus and maxillary palp brown ( Fig. 3 A); antenna pale brown, apical flagellomere darker ( Fig. 3 B). Thorax with general coloration brown, as in Figure 3 C; medial and lateral vitae, median anepisternum II, posterior anepisternum II, preepisternum and postnotum brown; antepronotum and scutellum pale. Wing membrane transparent, with spots and covered with macrotrichia, as in Fig. 1 E. Legs: femur with a pre-apical brown band; tibia with a basal and an apical brown band; ta1–ta4 with an apical brown band, ta5 pale. Abdomen and genitalia similar to male; seminal capsules dark brown.

Head ( Fig. 3 A). AR 0.30. Antenna with 11 flagellomeres; apical flagellomere 180 µm long; 37 µm wide, with a pre-apical setae 58 µm long; pedicel with 14 setae; scape with 6–7 setae. Eyes bare; dorsomedial extension well developed, 110 µm long, 100 µm wide, medially separated by 150 µm. Temporal setae 28, anteriorly multiserial, posteriorly uniserial. Clypeus 180 µm long, 157 µm wide, with 63 setae. Cibarial pump with anterior margin concave, 380 µm long and with orifice 95 from apex. Tentorium 185 µm long. Palpomere lengths (1–5 in µm): 65; 203; 204; 262; 380.

Thorax ( Fig. 3 C). Scutal tubercle absent; a strong medial scar present. Acrosthicals uncountable; dorsocentrals 68, multiserial anteriorly, biserial posteriorly; prealars 37; supraalar 3. Antepronotum with 11 lateral setae, tubercle present. Scutellum covered with setae of varying sizes. Preepisternals 7–8. Posnotum without setae.

Wing ( Fig. 3 E). Width 1.00 mm. Membrane with covering of macrotrichia; Costa 2.46 mm long, not produced beyond apex of R4+5, ending between M1+2 and M3+4.R2+3 present. MCu proximal to the RM. Brachiolum with 4 setae. Squama with 52 setae. Anal lobe well-developed. VR 0.93. WW 0.37.

Legs. Fore leg: tibia with 5 robust preapical bristles, 130 µm long; with an apical, pectinate spur, 58 µm long, with 7 lateral teeth and 1 elongate, curved apical tooth; width at apex of tibia 81 µm. Mid leg: tibia with 2 apical, pectinate spurs, 65 and 76 µm long, longest spur with 8 lateral teeth and 1 elongate, curved apical tooth, shortest spur with 7 lateral teeth and 1 curved apical tooth; width at apex of tibia 86 µm. Hind leg: tibia with two apical, pectinate spurs, 60 and 82 µm long, longest spur with 5 lateral teeth and 1 elongate, curved apical tooth, shortest spur with uncountable lateral teeth and 1 curved apical tooth; width at apex of tibia 87 µm. Tibial comb on hind leg with 6 bristles, the lateral longer than the medial ones. All legs with slender, hook-shaped claws. Pulvilli well developed. Lengths (in µm) and proportions of leg segments as in Table 2 .

Genitalia ( Figs. 3 D, 4). Tergite IX without setae. Three spherical seminal capsules, with 85 µm in diameter; spermathecal ducts separate for all of their length. Gonapophysis VIII rounded at apex. Coxosternapodeme strongly curved, 160 um long. Tergite X 240 um wide,with about 6 setae on each side. Notum 161 um long, Ra (ramus) elongate. Cercus 87 µm long.

Pupa (n=1–3). Total length 6.27 mm (abdomen and thorax).

Coloration. Cephalothorax brownish, thorax and wing sheath without distinct light spots ( Figs. 5 A–B); thoracic horn and plastron plate brownish. Abdomen brownish ( Fig. 5 C).

Cephalothorax. Thorax granulose, with a well-developed dorsal tubercle ( Fig. 5 A). Frontal apotome somewhat triangular ( Fig. 6 A). Wing sheath smooth, 1.58–1.65 mm long and 0.59–0.60 mm wide. Thoracic horn robust, wider at the apex, outer margin strongly convex, inner margin slightly concave ( Fig. 6 B), 3 26–370 µm long and maximum width 181–185 µm; plastron plate large and oval-shaped, 187–205 µm long. Horn sac well-developed, almost completely filling respiratory atrium and connected directly to the plastron plate. External membrane reticulate ( Fig. 6 B). Thoracic comb and basal lobe absent.

Abdomen ( Fig. 5 C). Tergite I with a distinct and elongate scar, 220–228 µm long. TI–TVII with large field of shagreen composed by short, branched spinules; TVIII with large field of shagreen composed by simple and branched spinules, with lateral areas without shagreen; anal lobe with shagreen. TI–TVI with 2 L setae on each side; T VII with 4 LS setae, distributed along the 2/3 distal of the segment, positioned at 171–190, 294–330, 446– 486 and 487–528 µm from base to apex of segment respectively ( Fig. 6 C). T VIII with 5 lateral filaments, placed at the 1/2 distal of the segment. Anal lobe as in figure 5D, 580–600 µm long, 545–550 µm wide at base, with 2 lateral macrosetae; outer and inner margins with spinules. Genital sac smaller than anal lobe, 353–365 µm long, 315–357 µm wide at base. GS/AL 0.61–0.66.

Larva (n=1–4). Total length 7.25–7.56 mm.

Coloration. Head pale yellow; postoccipital margin brown; apex of mandible dark; ligula brown, dark at apex. Abdomen whitish (alive larvae) or pale yellow (fixed in 80% ethanol); procercus half pale and half light-brown; anal setae brown. All posterior parapod claws pale yellow.

Head ( Fig. 7 A). Head capsule longish-oval; cephalic index 0.75. Chaetotaxy as in Figure 6 A. Dorsally S5 anterior to DP, S8 close to S7. Ventrally SSm posteromedial to clustered S9, S10, VP; S10 medial or slightly posteromedial to S9 and anterior to VP; VP posteromedial to S9; S9, S10 and SSm form an oblique line to longitudinal axis. SSm multibranched, S9 simple, S10 trifid.

Antenna. Length 317 µm long, A1 271–307 µm long, 25–26 µm wide, with ring organ placed 181–202 µm from base, A2 35–52 µm long. AR 5.12–5.89.

Maxilla ( Fig. 7 B). Basal palp segment 53–57 µm long and 12–16 µm wide, with ring organ placed 33–40 µm from base. A1/P1 5.11–5.39, A2/P1 0.48–0.66.

Mandible ( Fig. 7 C). Gradually curved, strongly narrowed in apical 1/2. Length 1 75–178 µm, with 3 lateral setae and 1 sensilla. Basal tooth very small, not easily seen, apically directed, 40–42 µm from apex; accessory tooth easily visible, immediately distal to basal tooth. A1/MD 1.55–1.72.

Mentum and M appendage ( Fig. 7 E). Dorsomental teeth reduced, labial vesicles well-developed, egg-shaped. M appendage triangular, bluntly rounded apically; pseudoradula 134 µm long, granulation thinner anteriorly and coarser posteriorly.

Hypopharyngeal complex ( Fig. 7 D). Ligula with five teeth, anterior row of teeth deeply concave; 87–93 µm long, 47–52, 32–35 and 40–46 µm wide at apex, middle and base respectively; point of inner teeth strongly inclined outwardly. Muscle attachment 63–75 µm long. Paraligula bifid, inner tooth shorter than outer tooth, 39–48 µm long. Pecten hypopharyngis with 16–18 teeth.

Body ( Fig. 8A ). With some scattered swim hairs. Anterior parapods with simple claws. Posterior parapod apex with hooklets and numerous simple claws, some slightly serrated. Subbasal seta of posterior parapod simple, 207– 235 µm long. Procercus 105–128 µm long, 37–48 µm wide, with 8 anal setae, 658–670 µm long. L/ W 2.63 –2.84. Supraanal seta 470–490 µm long. Anal tubules conical and short, 265 µm long.

Taxonomic remarks. The adult of the new species can be distinguished from M. corbii mainly by color pattern of the wings, legs and abdomen and by the preepisternals setae. Metapelopia peruensis sp. n. Has TI pale, TII–III with only a small medial brown spot and TVIII with two anteromedial large brown spots, contrasting with M. corbii which have TI–TVII with medial and anterolateral large brown spots and TVIII completely brown. In addition, femora with a preapical brown ring in M. peruensis sp. n differs from M. corbii , in which the apex is entirely brown. The new species has 5–6 (males) or 7–8 (female) preepisternals setae, while M. corbii has 2–3 (males) or 4 (female) preepisternals. The adults of M. peruensis sp. n. have a well-developed medial scar, as shown in Figure 1 E. However, this structure is difficult to be seen on the mounted specimen, perhaps for this reason it was not mentioned in the description of the genus ( Silva et al. 2014). Therefore, the presence of this structure should be included in the generic diagnosis.

The pupa of M. peruensis sp. n. can be distinguished from M. corbii and M. sp. 1 by having the plastron ovalshaped and by the position of the filaments in TVII, which are distributed along posterior 2/3 of the segment, whereas in M. corbii and M. sp. 1 the plastron is slightly rounded and filaments in TVII are distributed along posterior ½ of the segment.

The larva of M. peruensis sp. n. differs by the size of the muscle attachment, which is almost 3 times as long as in M. corbii . Other feature used in the diagnosis of the larva of M. peruensis sp. n. is the relative position of the cephalic bristles. However, using this feature should be done with caution since sometimes the heads of the larvae are crushed during the mounting of the slides, which may lead to changes in the relative position of the setal pits.

Distribution and bionomics. The species is known only from the type locality in Peru. At the type locality were recorded the following physic-chemical data: 15 m in width, temperature 14 °C and pH 4.8. Larvae and pupae were collected associated with algae accumulated on rocks ( Fig. 8 B).

Figures

FIGURE 1. Metapelopia peruensis sp. n., Adult male: A. Head. B. Thorax. C. Hypopygium. D. Wing. E. Male in dorsal view.

FIGURE 3. Metapelopia peruensis sp. n., Adult female: A. Head. B. Antenna. C. Thorax. D. Genitalia. E. Wing.

FIGURE 5. Metapelopia peruensis sp. n., Pupa: A. Thorax, in lateral view. B. Wing sheath. C. Abdomen, in dorsal view. D. T VII – VIII and Anal lobe.

FIGURE 6. Metapelopia peruensis sp. n., Pupa: A. Frontal apotome. B. Thoracic horn. C. Lateral setae on abdominal segment VII.

FIGURE 7. Metapelopia peruensis sp. n., larva: A. Head with chaetotaxy, left: dorsal view, right: ventral view. B. Maxillary palp. C. Mandible. D. Mentum and M appendage. E. Ligula and paraligula.

FIGURE 8. A. Metapelopia peruensis sp. n., larva, lateral view. B. Type locality, showing the environment in which the pupae and larvae of M. peruensis sp. n. were collected.

Tables

TABLE 1. Lengths (in µm) and proportions of leg segments of Metapelopia peruensis sp. n., male (n = 1).

Te	Ti	ta1	ta2	ta3	ta4	ta5	LR	BV	SV
P1 1175	1321	964	540	384	280	158	0.73	2.54	2.59
P2 1233	1270	775	393	290	217	135	0.63	3.17	3.23
P3 1118	1430	1018	546	423	269	162	0.71	2.55	2.50

TABLE 2. Lengths (in µm) and proportions of leg segments of Metapelopia peruensis sp. n., female (n = 1).

te	Ti	ta1	ta2	ta3	ta4	ta5	LR	BV	SV
P1 1235	1479	1002	514	388	305	171	0.68	2.70	2.71
P2 1445	1470	825	414	304	241	146	0.56	3.38	3.53
P3 1324	1755	1118	647	484	313	184	0.64	2.58	2.75