MadachironoMus , a new genus of tribe PseudochironoMini ( diPtera : chironoMidae , chironoMinae ) froM Madagascar

Madachironomus gen. n. is described based on male and female imagines collected at two watersheds in Madagascar. Two species are included, M. lakazana sp. n. from Lakazana River, Antananarivo province and M. rongaronga sp. n. from Rongaronga River, Toamasina province. The adults have a black comb on the apex of the fore tibia, similar to the combs on midand hind tibiae, thus placing the new genus in the tribe Pseudochironomini Sæther. The male has a strong, moderately long, nearly parallel-sided anal point with broadly rounded apex, without microtrichia except at base, and a digitiform, apically split median volsella with strong brush-like setae, projecting medially. The female sternite VIII has a very dense posteromedial to posterolateral field of setae, the gonocoxapodeme VIII is nearly straight, the gonapophysis VIII has closely adjacent, indistinctly separable lobes; the ovoid seminal capsules have nearly straight spermathecal ducts and the labia have internal apodemes and spinose chaetulae on dorsomedial surfaces.


Introduction
The tribe Pseudochironomini within the subfamily Chironomini was established by Saether (1977a: 154).The tribe is characterized by having a black comb on apex of 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, 1966, and Riethia Kieffer, 1917 were included in the tribe.
The genus Aedokritus was erected by Roback (1958); at present six described species distributed in South America are included (Trivinho-Strixino 1997).The genus Manoa was erected for M. obscura Fittkau, 1963, from the Amazon State in Brazil (Fittkau 1963).Later, M. tangae Andersen &Saether, 1997, from Tanzania, East Africa andM. pahayokeensis Jacobsen, 2002, from Florida, U.S.A and the Dominican Republic were described and a new species has also been found in Oriental China (Andersen & Saether 1997;Jacobsen & Perry 2002;da Silva et al. 2015;Xiaolong Lin pers. com.).The genus Megacentron was erected based on M. erebeum (Skuse, 1889) from Victoria in Australia by Freeman (1961); later M. cuneicalcar (Edwards, 1931) from Argentina and Chile was included.The genus Pseudochironomus, described by Malloch (1915), with 11 species in the Nearctic region, one species in the Palaearctic region and several, mainly undescribed species in the Neotropical region is the most species rich genus in the tribe; the Nearctic species were reviewed by Saether (1977b).The genus Riethia was erected by Kieffer (1917); at present five species distributed in the Australian and Neotropical regions are included (Trivinho-Strixinho et al. 2009).
The genus Psilochironomus was established by Sublette (1966) based on Chironomus fumeus Walley, 1934, from Guyana.Chironomus fumeus was described by Walley (in Curran 1934) from a single, incompletely preserved adult male and the brief description and sketchy drawing (Walley in Curran 1934: fig. 18) give no indication of any gonocoxite appendages.Sublette (1966) examined and redescribed the pinned remains of the holotype and reported that the genitalia were missing.Nevertheless, he proposed the new genus Psilochironomus, with P. fumeus (Walley) as the only member, stating that the genus "may be distinguished ... by the genitalia lacking superior and inferior appendages."However, today both Chironomus fumeus and Psilochironomus are considered to be nomina dubia in Pseudochironomini (see Spies & Reiss 1996: 90).
Below two new species from Madagascar are described, figured and placed in a new genus of the tribe Pseudochironomini.Both species have a black comb on the apex of the fore tibia, similar to the combs on mid-and hind tibiae, and the male has a digitiform, apically split median volsella with strong brush-like setae.http://zoobank.org/9B1973A5-5807-48C0-8942-2AD139F91232

Material and Methods
Molecular extraction for sequencing yielded no productive results, presumably due to the preservation (denatured alcohol) and age of the specimens.Prior to examination the specimens were mounted in Canada balsam following the procedure outlined by Saether (1969).Morphological terminology follows Saether (1980).Coloration is based on alcohol-preserved specimens.Measurements are given as ranges, followed by the mean when four or more specimens were measured, followed by the number of specimens measured in parentheses.
The holotypes and most paratypes will be deposited in the Zoologische Staatssammlung München, Munich, Germany (ZSM); the remaining paratypes will be kept in the Department of Natural History (ZMBN), Bergen University Museum, Norway.

Etymology:
The name of the new genus is a combination of the first two syllables from the place name Madagascar using the suffix -chironomus.

Generic diagnosis
The adults have the fore tibiae with one spurred comb, mid-and hind tibiae each with two separate, spurred combs; all combs subtriangular with rather steep flanks, the 1-2 pairs of teeth flanking the spur arising from the base of the latter and farther distally than the other comb teeth.The male has a strong, moderately long, nearly parallel-sided anal point with broadly rounded apex, without microtrichia except at base, and a digitiform, apically split median volsella with strong brush-like setae.The female has sternite VIII with a very dense posteromedial to posterolateral field of setae, a nearly straight gonocoxapodeme VIII, gonapophysis VIII with closely adjacent, indistinctly separable lobes, ovoid seminal capsules with nearly straight spermathecal ducts and labium with internal apodeme and spinose chaetulae on dorsomedial surfaces.
Head.Frontal tubercles absent.Temporal setae consisting of inseparably intergrading verticals and postorbitals, briefly bi-to tri-serial near transition of eye to its dorsomedial extension.Eye bare; dorsomedial eye extension parallel-sided, about 2.5 times as wide as high, mostly of 5 facets per diagonal; interocular distance in frontal view about 3 times the apical width of the extension, slightly lower dorsally than ventrally.Clypeus with numerous setae arising over nearly entire surface.Palp 5-segmented, palpomere 3 with 2-3 sensilla clavata apically.
Thorax.Not projecting anterodorsally or arching overhead; scutal tubercle absent.Antepronotum visible in dorsal view, medially with relatively narrow but deep V-shaped notch, each lobe narrowest in mid-section; in lateral view with dorsal projection to anterior and with curved subsurface contour indicating the anteromedial excavation; with dorsal and ventrolateral semi-spinose, short setae.Acrostichals weak, numerous, paired or interspersed with small, light spots without alveoli or setae; setae short, semi-spinose, occurring from near antepronotum to almost as far posterior as dorsocentrals.Dorsocentrals weak, numerous, unito irregularly tri-serial, beginning above parapsidal suture, setae slightly longer than acrostichals.Prealars uniserial to bi-serial.Supraalars absent, exceptionally 1. Scutellum with numerous weak setae, bi-to tri-serial.Alveoli of all thoracic setae not surrounded by circles lighter in color than adjacent surfaces.
Wing.Costa weakly extended, ending proximal to wing apex.R 2+3 ending at one third of the distance between apices of R 1 and R 4+5 .FCu slightly proximal to RM. Brachiolum with 2-3 setae; costal extension with few non-marginal setae; R 4+5 occasionally with single seta apically; other veins and membrane bare.Squama with numerous, partly bito tri-serial setae.
Legs.Fore tibia with single, dark comb, with central protruding long spur; mid-and hind tibia with two triangular combs, each with protruding central spur.Fore tarsal beard absent.Pseudospurs absent.Sensilla chaetica present in proximal 1/3 of ta 1 of mid-and hind leg.Pulvillus pad-like, ventrally covered with elongate trichia, broadly triangular, shorter than empodium, reaching beyond tip of fifth tarsomere to about mid-length of claw.
Hypopygium.Anal point tapering to apex that is tongue-shaped in dorsal view, subacute and slightly curving ventrad in lateral view, without microtrichia except at base.Tergite IX with several weak setae to each side of the base of anal point.Phallapodeme well developed, aedeagal lobe with narrow, curved oral projection.Transverse sternapodeme narrow, strongly arched, with low, rounded orolateral projections.Pars ventralis absent.Median volsella composed of elongate, digitiform main stem, split in apical 2/3, projecting posteromedially, densely covered with more or less subulate setae, and with cluster of additional, long subulate setae arising from gonocoxite next to proximal corner of volsella.Superior volsella distally sclerotized, darker than surrounding structures, projecting caudad, not reaching past anal point or distal end of gonocoxite, with broadly triangular base with 1-2 dorsolateral setae, and hooked apical part with few mesally directed setae, without microtrichia on dorsal surface.Inferior volsella broadly digitiform in dorsal view, with microtrichia and normal to strong setae along entire medial length, on distal-dorsal surface and less densely distolaterally; proximoventrally with globose, more membranous expansion.Gonocoxite with 4 ventromedial setae proximal and 3 distal to median volsella.Gonostylus weakly curved with bluntly rounded apex, with row of short, curved setae along inner margin.

Adult female
As male except antenna with 6 flagellomeres; AR about 0.6; flagellomeres 1-5 each with submedial whorl of 3-5 strong setae and with subapical ring of 2-4 sensilla chaetica; flagellomere 6 with 15-20 sensilla chaetica in apical 3/4.Dorsomedial eye extension less distinct than in male, about 1.2 times as wide as high, mostly of 5-6 facets per diagonal; eyes separated by more than three times the width of the eye extension.Wing veins darker brown than in male, with dark spot along crossvein RM and radial fork; membrane brown with stronger shading along veins.Wing vein R 2+3 ending about half-way between apices of R 1 and R 4+5 .
Abdomen.Tergites I, II, IV-VIII with successively increasing numbers of widely scattered, relatively short but strong setae arising in light-colored circles; tergite III with setae mostly concentrated anteriorly and posteriorly and few setae in between.Paratergites IV (except anteriorly) -VII with conspicuous longitudinal setation.Sternites II-V with (postero)lateral longitudinal rows or patches of setae, sternites VI-VII with these patches spreading to medial and anterior; in addition, sternites VI-VII with marginal rows of setae paralleling those on paratergites; sternite VII with posteromedial triangular field of more densely set setae.
Genitalia.Sternite VIII with very dense posteromedial to posterolateral field of setae; zone of transition from sternite to genital bay densely covered with medially directed trichia of various sizes, some arising from papillar but non-alveolar bases; posterior margin of sternite VIII on either side of genital bay with a more or less distinct peak to posterior.Vaginal floor conspicuous in ventral view as a pair of darkened, anteromedially narrowly fused areas; anterior and lateral margin of floor with narrow sclerotization that is posteriorly connected to the gonocoxapodeme VIII; dorsal (intra-vaginal) surface of floor with loosely spaced microtrichia.Gonocoxapodeme VIII nearly straight, extending from dorsal of anteromedial margin of floor to near posteromedial peak of sternite VIII, hardly reaching farther lateral than coxosternapodeme.Gonapophysis VIII with closely adjacent, indistinctly separable lobes.Dorsomesal lobe anteriorly parallel to inner margin of floor with greatest width near posterior end.Ventrolateral lobe arising anteromedial of posteromedial peak of sternite VIII, apparently consisting of two membranous lobes with microtrichia and fine dissections along its medial margin.Apodeme lobe with conspicuous transverse apodeme dorsal of posterior end of dorsomesal lobe, and with extensive soft membrane to medial and posterior that carries many trichia and fine striations on its margin and at least anteroventral surface.Notum extending through most of length of segment VIII, much longer than seminal capsule, free rami very short or indistinct.Seminal capsule ovoid, spermathecal duct nearly straight, carrying secretory cells, subapically narrowing, the two ducts meeting at their joint opening.Coxosternapodeme with extensive anterolateral part carrying a diagonal dorsal ridge, and with narrow anteromedial and posterior extensions.Labium with diagonal internal apodeme and fine to spinose chaetulae on dorsomedial surface.
Tergite IX shallowly hemispherical, with setae indistinctly separated in two groups, and with a posteromedial brown streak that leads towards a sclerotized external tubercle.Gonocoxite IX with dorsal, lateral and ventral setae.Segment X without setae, ventrally with large triangular postgenital plate, dorsally with even longer mediocaudal projection.Cercus long with anterior end curving to lateral where it is fused to segment X.

Systematics
The new genus is similar to the other genera of the tribe Psudochironomini in having a black comb on the apex of the fore tibia, similar to the combs on mid-and hind tibiae.The males of the genera Manoa, Pseudochironomus and Riethia all lack an anal point, while Aedokritus has a triangular anal point covered with microtrichia at least in basal one half, and Megacentron erebus (Skuse, 1889) has a rather narrow, spatulate anal point apparently without microtrichia except at base.The male of the new genus has a strong, moderately long, nearly parallel-sided anal point with broadly rounded apex, without microtrichia except at base.It also has a has a digitiform, apically split median volsella with strong brush-like setae, projecting medially, while both Aedokritus and Megacentron have median volsellae projecting caudally.The female genitalia are complex, differing quite strongly from the genitalia of Pseudochironomus and Manoa as described by Saether (1977a), particularly in the shape of gonapophysis VIII.
Etymology.Named after Lakazana River, Antananarivo province, Madagascar, where the species was collected.The name is to be regarded as a noun in apposition.

Diagnostic characters.
See diagnostic characters for the genus.The female can be separated from the female of M. rongaronga sp.n. as it is larger, with a wing length of 4.16-4.18mm compared to 3.11-3.58mm in M. rongaronga, has a slightly lower antennal ratio (AR = 0.58-0.66compared to AR = 0.70-0.81)and has distinctly more setae on segment X to each side of vagina (189-231 setae compared to 53-78 setae).
Coloration.Head, antennae and palpi brown.Thorax mostly brown with lateral mesonotal dark brown spot.Legs medium brown, foreleg with tibia and ta 2-5 brown, fore tibia with dark brown apex, fore ta 1 lighter brown with dark brown apex; mid-and hind legs with lighter brown tarsi.Wing membrane (Fig. 8) translucent with brownish stain and some light shaded areas e.g.proximally and distally in cell c, along most of sc, proximal in r 4+5 and along Cu and proximal parts of M 3+4 and Cu 1 ; wing veins brownish, crossvein RM and radial fork darker brown.Abdominal segment 1 pale brown, abdominal segments 2-5 light brown with narrow anterior transverse brown band; segments 6-8 and hypopygium brown.
Coloration.Generally distinctly darker than male.Head, antennae and palpi brown.Thorax mostly brown, lateral mesonotal dark spot less contrasting than in male, indistinct in some specimens.Legs medium brown; foreleg with tibia and ta 2-5 darker brown, fore tibia with dark brown apex, fore ta 1 lighter brown with dark brown apex; mid-and hind legs with lighter brown femoral apices and tarsi.Wing membrane translucent with brownish stain and some more darkly shaded areas, e.g.proximally and distally in cell c, along most of sc, proximally in r 1 and r 4+5 , along Cu and proximal parts of M 3+4 and Cu 1 ; veins brown, crossvein RM and radial fork darker brown.Abdominal tergites and posterior sternites brown, anterior sternites light brown, anterior transverse segment bands indicated in some specimens; hypopygium medium brown.

Discussion
Cranston (2003: 184) described Pseudochironomini as "almost certainly a paraphyletic grade", and according to Epler et al. (2013: 433) the "validity and characteristics of a tribe Pseudochironomini are uncertain".As reflected in these statements, considerable evidence needs to be gathered and evaluated before this opinion could become a widely accepted systematic result.In any case, note that these doubts address the relatively wide concept of the tribe drawn up by Saether (1977a: 154).If Pseudochironomini proves untenable in the traditional sense, the name might still be applied to any monophylum that includes the type genus, Pseudochironomus, but excludes one or more of the other currently included genera, provided that the resulting smaller clade still warrants the status of a tribe.Andersen et al. (2011: 48) indicated one such possibility, but also found the available data to be insufficient for a meaningful conclusion.Polukonova et al. (2013) analyzed amino acid proportions in the barcoding section of the COI gene from various Chironominae species, and reported the observed divergences among taxa to increase significantly with each higher systematic rank.They proposed that corresponding divergence observed in any pair of species or genera indicates whether or not the two taxa belong to the respective same genus, tribe or subfamily.Applying this to the Chironominae, they found support for the distinction of three major subdivisions, one of these 'tribes' being Tanytarsini in the traditional sense.However, another 'tribe' combined Pseudochironomus ("P.sp." from GenBank; the genus might be misidentified) with Polypedilum Kieffer and Sergentia Kieffer, Endochironomus Kieffer and Synendotendipes Grodhaus, whereas in the third 'tribe' Riethia ("R.stictoptera" from GenBank) clustered with the remainder of Chironomini.
The latter association is fundamentally different from the results of Cranston et al. (2012;Pseudochironomus not included), whose multi-gene analysis had Riethia so far removed from Polukonova et al.'s 'remaining' Chironomini that the two are not even part of the same larger monophylum.However, the two sets of results agree in suggesting that the tribes Chironomini and Pseudochironomini look untenable in their traditional definitions.More research is thus needed to clarify the status of the tribe Pseudochironomini.