New species and records of Pseudochironomini Sæther, 1977 (Diptera, Chironomidae) from the Dominican Republic

Abstract Background Pseudochironomini is a relatively small and poorly-studied tribe of subfamily Chironominae (Diptera, Chironomidae). New information Pseudochironomusruthae Andersen & Baranov sp. nov. is described and figured, based on a single male collected in a light trap at Matadero, Dominican Republic. The species can be separated from its congeners by the combination of the following characters: wing without dark bands, dorsocentrals in partly double row and apex of superior volsella rounded. The species is the first Pseudochironomus species to be formally recorded and described from the Caribbean. In addition, a new record of Manoapahayokeensis Jacobsen & Perry, 2002 from the Dominican Republic is given. One specimen was DNA-barcoded and the barcode is given.


New information
Pseudochironomus ruthae Andersen & Baranov sp.nov. is described and figured, based on a single male collected in a light trap at Matadero, Dominican Republic.The species can be separated from its congeners by the combination of the following characters: wing without dark bands, dorsocentrals in partly double row and apex of superior volsella rounded.The species is the first Pseudochironomus species to be formally recorded and

Introduction
The tribe Pseudochironomini within the subfamily Chironominae was established by Saether (1977a).The tribe is characterised by having a black comb on fore tibia, similar to the combs on mid-and hind tibiae and, in the male, the median volsella is generally present.Originally, the genera Aedokritus Roback, 1958, Manoa Fittkau, 1963, Megacentron Freeman, 1961, Pseudochironomus Malloch, 1915, Psilochironomus Sublette, 1966and Riethia Kieffer, 1917 were included in the tribe ( Saether 1977a).However, Psilochironomus is now considered to be a nomen dubium ( Spies and Reiss 1996).Later, Andersen (2016) added the genus Madachironomus Andersen, 2016, based on two species from Madagascar to the tribe.According to Cranston (2003), the tribe Pseudochironomini might not be monophyletic.
The genus Pseudochironomus was described by Malloch (1915), based on P. richardsoni Malloch, 1915 from Illinois, USA.Pseudochironomus is the most species-rich genus in the tribe.About 11 species are known from the Nearctic Region and one or two species from the Palaearctic Region (Epler et al. 2013).The Nearctic species were reviewed by Saether (1977b).From the Neotropical Region, Kieffer (1925) described P. viridis Kieffer 1925from Argentina. Roback (1960) recorded the species from Peru and re-described the male.Later, Paggi and Rodriguez-Garay (2015) re-described and figured the male, female, pupa and larva in more detail, based on material from Argentina.Recently, Shimabukuro et al. (2017) andTrivinho-Strixino andShimabukuro (2018) described eight new Pseudochironomus species from Brazil and Andersen (2023) described a new species from Mexico and Costa Rica.Additionally, Watson and Heyn (1993) reported at least 11 (likely undescribed) species of Pseudochironomus as well as Pseudochironomus cf.viridis.
No Pseudochironomus species have been described from the Caribbean so far, but Silva et al. (2015) listed the genus from the Dominican Republic, as well as reporting Manoa pahayokeensis Jacobsen & Perry, 2002.Below, we describe a new species of Pseudochironomus from the country.It can be separated from other Pseudochironomus species by having the wing without dark bands, dorsocentrals in a partly double row and the apex of superior volsella is rounded.We also report a new record of M. pahayokeensis from the Dominican Republic.

Materials and methods
When collected, the specimens were preserved in 80% ethanol and later slide-mounted in Euparal following the procedure outlined by Saether (1969).The morphological nomenclature follows Saether (1980).
The specimens were collected under the collection permit of Ministro de Medio Ambiente y Recursos Naturales of Dominican Republic for the project "Long peace of the Caribbeanhave biota of the Dominican Republic really remained virtually unchanged for over 13 million years?" and were exported under export permit # VAPB-07404.The holotype of Pseudochironomus ruthae Andersen & Baranov sp.nov. is deposited in the collection at the Department of Natural History, University Museum of Bergen, Norway [ZMBN].The material of Manoa pahayokeensis Jacobsen & Perry is housed in the Bavarian State Collection of Zoology (SNSB-ZSM).
The DNA was extracted from the material at the SNSB molecular lab using the NucleoSpin 96 Tissue (Macherey-Nagel) DNA extraction kit after having undergone an overnight lysis at 56°C.The COI barcodes were amplified using the LepF1 and LepR1 standard barcoding primers (Leray et al. 2013) using a Biometra Thermocycler (Analytik Jena) and the following PCR conditions: 2 min at 94°C; first cycle set (5 repeats): 30 s denaturation at 94°C, 40 s annealing at 45°C and 60 s extension at 72°C.Second cycle set (35 repeats): 30 s denaturation at 94°C, 40 s annealing at 51°C and 60 s extension at 72°C; final elongation 10 min at 72°C.The PCR products were cleaned-up using the ExoSAP-IT Express (Thermo Fisher) Kit, then sent to the LMU Sequencing Service at Biozentrum (Martinsried, Germany) for Sanger sequencing.Every specimen's COI barcode was sequenced as a forward and reverse strand.The traces were edited in BioEdit Hall (1999) and a consensus sequence of the forward and reverse strands was obtained and uploaded to Barcode of Life Data Systems (www.boldsystems.org)(Ratnasingham and Hebert 2007).The original traces were uploaded as well.

Diagnosis
The species can be separated from its congeners by the combination of the following characters: wing without dark bands, dorsocentrals in partly double row and apex of superior volsella rounded.

Etymology
Named after Ruth Bastardo who runs the aquatic ecology group and without whom the specimen would not have been collected.

Taxon discussion
The new species is quite distinct from other described Neotropical Pseudochironomus species by the combination of having a wing without dark bands, dorsocentrals in a partly double row and apex of the superior volsella bluntly rounded.It is most similar to the Nearctic Pseudochironomus richardsoni Malloch, 1915(Saether 1977a), but differs on the narrower median volsella of Pseudochironomus ruthae (vs.wider conical one of the P. richardsoni), more triangular inferior of volsella of P. ruthae, rather than an elongated one of P. richardsoni; additionally, P. ruthae has a lower number of dorsocentrals (37 vs. 59 in P. richardsoni) ( Saether 1977a).In the key to the Pseudochironomini occurring in Brazil, it falls next to P. jordensis Shimabukuro &Trivinho-Strixino, 2017 andP. mocidade Shimabukuro &Trivinho-Strixino, 2017, as the wing of the adult male is longer than 3.0 mm and the posterior margin of terigte IX has a median notch (Trivinho-Strixino andShimabukuro 2018, Shimabukuro et al. 2017).Hovewer, P. ruthae is distinct from all other South American Pseudochironomus species by possessing a superior volsella with a blunt, rounded apex, instead of the elongated beak-like protrusions, apparent in both P. jordensis and P. mocidade.Unfortunately, we were not able to DNA sequence the new species and its phylogenetic relationships to other representatives of the genus will require further elucidation.

Taxon discussion
This species was originally described from the Everglades in Florida, USA and has previously been recorded from Monte Blanco, in the eastern parts of the Dominican Republic (Silva et al. 2015, Jacobsen andPerry 2002).During the present project, two males (Fig. 3) and two females were collected with sweep nets at Rio Blanco, in the central part of the Dominican Republic.The specimens were collected next to a small, approximately 6 m wide, fast flowing river Rio Blanco.

Notes
COI sequences of M. pahayokeensis were deposited in GenBаnk under accession numbers OR670329 and OR670330 (obtained from specimens "a" and "b", respectively).supporting the publication fees through the CSIC Open Access Publication Support Initiative from the CSIC Unit of Information Resources for Research (URICI).