Limnophyes llanero, Dantas & Ramos-Pastrana & Hamada, 2022

Dantas, Galileu P. S., Ramos-Pastrana, Yardany & Hamada, Neusa, 2022, A new species of Limnophyes Eaton, 1875 (Diptera: Chironomidae) from Llanos Orientales, Colombia, Zootaxa 5141 (3), pp. 295-300 : 296-299

Limnophyes llanero sp. n.

Type material. Holotype: male, COLOMBIA, Meta department, Puerto Lopéz, Cond. Campestre Sol del Llano , 04º08’11’’N, 72º52’53’’W, 211 meters a.s.l., 25.i.2021, Malaise trap, Ramos-Pastrana Y. leg. ( LEUA – 43037).

Etymology. Llanero is the name given to people and things from the Llanos, the ecoregion where the new species was collected. The name is to be treated as a noun in apposition.

Diagnostic characters. Male. Antenna with 13 flagellomeres, AR 0.90; with scattered lanceolate setae present in the humeral and prescutellar area; epimeron II with six setae, posterior anepisternum II with one seta, preepisternum without setae; apex of gonostylus expanded, with well-developed crista dorsalis.

Description. Male (n = 1). Total length 1.57 mm. Wing length 0.85 mm. Total length/wing length 1.84. Wing length/profemur length 2.26.

Coloration ( Figs. 1A–D ). Blackish brown; wing membrane with pale brownish tinge; legs uniformly dark brown except trochanter and base of the femora pale.

Antenna. AR 0.90. With 13 flagellomeres, ultimate flagellomere 268 µm long.

Head ( Fig. 1A ). Temporal setae 5, including 2 inners vertical, 1 outer vertical and 2 postorbitals. Clypeus with 12 setae. Tentorium 106 µm long, 17 µm wide at sieve pore, 10 µm wide at posterior tentorial pit. Stipes 90 µm long, 5 µm wide. Palp segment lengths (in µm): 17, 21, 48, 65, 108. Third palpomere with at least one sensilla clavata in apical third, 8 µm long.

Thorax ( Fig. 1B ). Antepronotal lobes slightly projecting dorsally. Antepronotals consisting of 3 lateral and 5 dorsal setae. Acrostichals small, in lateral view difficult to discern from the microtrichiae covering the thorax. Dorsocentrals consisting of 5–7 scattered lanceolate setae in the humeral area, 4 lanceolate prescutellars and 10 simple setae; prealars 7–8, extending anteriorly in single row; preepisternum without setae; posterior anepisternum II with 1 seta; epimeron II with 5 setae. Scutellum with 5 setae.

Wing ( Fig 1C ). VR 1.39. Costal extension 80 µm long. C with 56 setae, R with 2 setae, brachiolum with 1 seta, other veins bare. Squama with 4 setae. Wing membrane with coarse punctation.

Legs. Foreleg: femur 378 μm long; tibia 462 μm long, with single, apical spur 43 μm long; tarsomere lengths (ta 1 –ta 5 in μm): 268, 152, 115, 60, 50; LR 0.58, BV 2.94, SV 3.13. Mid leg: femur 360 μm long; tibia 355 μm long, with two apical spurs 20 μm long; tarsomere lengths (ta 1 –ta 5 in μm): 195, 86, 60, 35, 45; LR 0.55, BV 4.03, SV 3.67. Hind leg: femur 370 μm long, tibia 440 μm long, with an apical spur 39 μm long; comb with 11 bristles; tarsomere lengths (ta 1 –ta 5 in μm): 247, 108, 105, 44, 49; LR 0.56, BV 3.45, SV 3.28. Claws curved, pulvilli multi-branched.

Hypopygium ( Figs. 2A–C ). Anal point well-developed, triangular, covered with microtrichia and with about 6 marginal setae ( Fig. 2A ); laterosternite IX with 3 setae. Phallapodeme 48 µm long, with median bi- or trifurcated projection; transverse sternapodeme arched, 65 µm long. Virga consisting of two spines, 26 µm long. Gonocoxite 100 µm long; inferior volsella of minimus -group type. Gonostylus 56 µm long, expanded at apex; crista dorsalis well-developed; megaseta forked, 10 µm long. HR 1.79; HV 2.80.

Female imago and immatures. Unknown.

Taxonomic remarks. The new species is described based only in one specimen due to the low density, represented by the number of specimens collected in the Malaise trap, however, with the morphological characteristics presented in the description section there is no doubt about its identity. In the key to males of Neotropical Limnophyes species ( Pinho & Andersen 2015), the new species key to couplet 6: L. subnudicolis ( Edwards, 1931) from Argentina and L. mariae Sublette & Sasa, 1994 from Guatemala. However, Limnophyes llanero sp. n. has six setae on epimeron II and the gonostylus has a well-developed, apical crista dorsalis, while L. subnudicolis lacks setae on epimeron II and has a low crista dorsalis placed medially. Antenna with 13 flagellomeres and a well-developed crista dorsalis differentiates the new species from L. mariae , which has an antenna with 12 flagellomeres and a very weak crista dorsalis. In the key to the Nearctic species provided by Saether (1975), L. llanero sp. n. key to at couplet 12, not matching any of the alternatives, mainly due to the absence of setae on preepisternum. The Nearctic species L. cristatissimus Saether, 1975 also has the gonostylus apically widened with a large crista dorsalis, but the presence of setae on the preepisternum, absence of lanceolate humerals and a rounded anal point separate the two species, L. llanero sp. n. lacks setae on preepisternum, has lanceolate humerals and a cone-shaped anal point. When reviewing the species of Limnophyes from the Holarctic and Afrotropical regions, Saether (1990a) provided generic diagnosis and descriptions, discussed the phylogeny, and proposed species groups for the genus. Notwithstanding the volsella and virga of L. llanero sp. n. having shapes that resemble those found in the minimus -group of Saether (1990a), the absence of preepisternals and the strongly enlarged, apical crista dorsalis, the new species differ from the diagnosis of the minimus -group, which is characterized by preepisternum with an anterior row of setae and a pointed crista dorsalis.

Distribution and bionomics. The species is known only from the type locality in central Colombia, where the vegetation is a mosaic of savanna, mainland forests, and flooded forests ( Fig. 3A ). The holotype was collected in a Malaise trap placed across a one-meter wide stream with negligible current. About 10 meters downstream the stream was dammed forming a small pond. The stream is bordered by a relatively well-preserved gallery forest ( Fig. 3B ). The type locality of the new species, the Llanos Orientales, is considered one of the most threatened ecoregions in Colombia due to the high human population growth and the intensification of land use, such as expansion of road infrastructure, petroleum activities, mining, and monoculture ( Romero-Ruiz et al. 2012). This situation reinforces the need to increase the knowledge on the biodiversity in this ecoregion to understand the anthropogenic impacts on the biota and to use this knowledge as tools to develop conservation strategies.

Figures

FIGURE 1. Limnophyes llanero sp. n. (Diptera: Chironomidae), adult male:A. Head, in frontal view. B. Thorax, in lateral view. C. Wing. D. Abdomen, in dorsal view.

FIGURE 2. Limnophyes llanero sp. n. (Diptera: Chironomidae), adult male: A. Hypopygium, in dorsal view. B–C. Hypopygium in dorsal view, with tergite IX removed. Scale bar = 50 µm.

FIGURE 3. Type locality of Limnophyes llanero sp. n. in central Colombia. A. The red arrow points to the location where the trap was placed. B. Malaise trap placed at the type locality.