Pseudochironomus ruthae Andersen & Baranov, 2023

Andersen, Trond, Hoecherl, Amelie, Huebner, Jeremy, Chimeno, Caroline, Lin, Xiaolong & Baranov, Viktor A., 2023, New species and records of Pseudochironomini Saether, 1977 (Diptera, Chironomidae) from the Dominican Republic, Biodiversity Data Journal 11, pp. 111925-111925 : 111925

Pseudochironomus ruthae Andersen & Baranov sp. nov.

Materials

Type status: Holotype. Occurrence: occurrenceID: A5E2B29A-388F-5FCA-9FF3- 728AD 814291D; Taxon: scientificName: Pseudochironomus ruthae Andersen & Baranov; Location: continent: Central America; waterBody: Caribbean; islandGroup: Greater Antilles; island: Hispaniola; country: Dominican Republic; countryCode: DO; stateProvince: Azua; municipality: Guayabal; locality: El Naranjito Matadero ; minimumElevationInMeters: 1400; maximumElevationInMeters: 1400; verbatimLatitude: 18 40 27.70N; verbatimLongitude: 70 42 03.30W; georeferencedBy: Amelie Höcherl; Event: samplingProtocol: light trap, Amelie Höcherl; eventDate: 10 November 2019; startDayOfYear: 10 Nov; endDayOfYear: 10 Nov ; year: 2019; month: November ; day: 10; habitat: Location next to a nearly dry stream in a forested area; Record Level : type: PhysicalObject ; language: en; rights: Reconocimiento 3.0 España (CC BY 3.0 ES); rightsHolder: CSIC; institutionID: University Museum of Bergen , Norway; institutionCode: ZMBN; basisOfRecord: PreservedSpecimen

Description

Male (n = 1). Total length 4.64 mm. Wing length 2.12 mm (Fig. 1 ). Total length/wing length 2.19. Wing length/length of profemur 2.24.

Colouration: Head and thorax dark brown; abdomen and legs brown, abdominal tergites VII and VIII with posterior lighter brown subrectangular field.

Antenna: AR 2.28. Ultimate flagellomere 1004 μm long.

Head: Temporals apparently about 25 in double to multiple rows. Clypeus with about 20 setae. Tentorium and stipes not measurable. Palp segment lengths (in μm): 67, 94, 162, 201 and 267. Third palpomere with all together four sensilla clavata in two pits apically, longest 21 μm long.

Thorax: Antepronotum with seven setae. With about 37 dorsocentrals in mainly double rows. Pre-alars six in single line. Scutellum with about 28 setae.

Wing (Fig. 1 ): VR 1.06. Brachiolum with two setae, R with 15 setae, remaining veins and cells bare. Squama with 17 setae.

Legs: Spur of fore tibia 66 μm long, spurs of mid-tibia 79 μm and 68 μm long, spurs of hind tibia 90 μm and 75 μm long. Width at apex of fore tibia 62 μm, of mid-tibia 77 μm, of hind tibia 80 μm. Sensilla chaetica five on ta1 of both mid- and hind legs. Lengths and proportions of legs as in Table 1 .

Hypopygium (Fig. 2 ): Tergite IX with broadly rounded posterior margin, with small median notch with single strong setae on weak tubercle to each side; with 43 additional dorsal and marginal setae. Laterosternite IX with four setae. Transverse sternapodeme straight, 138 μm long, with strong oral projections. Phallapodeme 164 μm long. Gonocoxite 248 μm long. Superior volsella pediform, 113 μm long, 41 μm wide medially, with rounded projection anteriomesally with single sensilla subapically. Inferior volsella with subovate apical part and base set of centrline of the hypopigium; apical part 104 μm wide, mesally with ridge with row of setae. Median volsella digitate, 17 μm long, with two strong and one weaker seta apically. Pars ventralis 88 μm long, narrow, apparently split at 1/3, apical parts 11 μm wide at base. Gonostylus 133 μm long. HR = 1.87; HV = 3.49.

Female and immatures. Unknown.

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.

Distribution

Dominican Republic: El Naranjito Matadero, 18°40'27.70"N, 70°42'03.30"E.

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 ( Sæther 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 ) ( Sæther 1977a). In the key to the Pseudochironomini occurring in Brazil, it falls next to P. jordensis Shimabukuro & Trivinho-Strixino, 2017 and P. 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 and Shimabukuro 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.

Figures

Figure 1. Pseudochironomus ruthae Andersen & Baranov sp. nov., male. Wing.

Figure 2. Pseudochironomus ruthae Andersen & Baranov sp. nov., male. a Hypopygium, dorsal view; b Hypopygium with tergite IX removed, dorsal view; c Hypopygium, ventral view; d Superior volsella; e Inferior volsella; f Median volsella; g Pars ventralis.