Taxonomic revision of two poorly known genera of Richardiidae ( Diptera ) : Maerorichardia and Odontomerella

Richardiidae are a family of Tephritoidea in which most genera are poorly known taxonomically, including some which were poorly described with limited or no illustrations. With the aim to decrease this taxonomic gap, herein we review two scarcely known monotypic genera: Odontomerella Hendel, 1912 and Maerorichardia Hennig, 1937, both known only from the holotypes of their type species. Maerorichardia is the only genus of Richardiidae with mid and hind tibiae thicker than their respective femora, and the wing with the anal lobe distinctly developed. Odontomerella can be distinguished from the others richardiids by the postcranium reduced and little wider ventrally, the compound eye well developed, occupying most of the head, with the gena and postcranium very reduced, and the face short, with the oral margin distinctly concave. The limits of both genera are revised and better supported with the addition of new diagnostic characters. Odontomera flavipleura Hennig, 1938 is transferred to Odontomerella. The types of the species are revised and illustrated.

Richardiidae are a small family of about 200 valid species (STEYSKAL 1968, WENDT & ALE-ROCHA 2014b, 2015) in 32 genera (HANCOCK 2010).The family only occurs in the New World, and the vast majority of species are recorded from the Neotropical Region (ACZÉL 1950, STEYSKAL 1968).
During the last five decades, richardiids were largely neglected and only a few sparse contributions were published during that period.Recently, however, the family has been the focus of more extensive taxonomic studies.Examples are an identification key to all genera (HANCOCK 2010) and revisions of several genera (WENDT & ALE-ROCHA 2012, 2014b), including new taxa (e.g.PEREZ-GELABERT & THOMPSON 2006, CARVALHO et al. 2011, ALENCAR et al. 2013, WENDT & ALE-ROCHA 2014a, b, 2015).Despite these efforts, however, many taxa still remain undescribed or scarcely studied.
Herein, we revise two poorly known genera: Odontomerella Hendel, 1912 andMaerorichardia Hennig, 1937.Both are monotypic, known only from their respective holotypes.HENDEL (1912) described Odontomerella to accommodate Odontomerella oxyptera Hendel, 1912, based on a single male specimen.It has never been illustrated and recognition of this genus has remained uncertain.Maerorichardia was proposed by HENNIG (1937) to include Maerorichardia lugubris Hennig, 1937, based on a single female specimen.This genus is recognized by the mid and hind tibiae being distinctly thickened (HANCOCK 2010) and with a very characteristic wing: the alula and anal lobe are well developed.These diagnostic characters, as well as those for Odontomerella, have never been illustrated or described in detail.Herein, the limits of these genera are revised and better characterized with the addition of new diagnostic characters.The holotypes of these species are also redescribed and illustrated.Odontomera flavipleura Hennig, 1938 is transferred to Odontomerella and is redescribed and illustrated.Diagnosis and illustrations of head, wing, and male and female terminalia of Odontomera Macquart, 1843 are also provided to justify the transference of O. flavipleura to Odontomerella.

MATERIAL AND METHODS
The examined specimens were borrowed from the following collections, with the curators listed in parentheses: BMNH -Natural History Museum, London, England (K.Goodger); LACM -Natural History Museum of Los Angeles County, California, USA (B.Brown; originally, the material belonged to Utah State University, Entomological Museum, Logan, Utah, USA (EMUS), and it was loaned by W.J. Hanson, but recently the Diptera from this collection were transferred to LACM); MHNJP -Museo de História Natural Javier Prado, Universidad Nacional Mayor de San Marcos, Lima, Peru (G.L. Müller); SMTD -Senckenberg Natural History Collections, Dresden Museum of Zoology, Dresden, Germany (U. Kallweit); USNM -National Museum of Natural History, Washington, D.C., USA (A.L.Norrbom).
The external morphological terminology follows CUMMING & WOOD (2009), whereas the female and male terminalia terminologies follow NORRBOM &KIM (1988) andWHITE et al. (1999), respectively.Measurements of the head are presented as proportions, which were calculated always with the head in frontal view: 1) head width-height ratio: the greatest width of the head, including the eyes, divided by the greatest height of the head, measured from the vertex to the ventral limit of the face, without the clypeus; 2) frons-head ratio: the greatest width of the frons divided by the greatest width of the head; 3) frons width-height ratio: the greatest width of the frons divided by the greatest height of it, measured from the vertex to the dorsal margin of the lunule; 4) face-clypeus ratio: greatest height of the face, measured from the ventral margin of the scape insertion to the ventral limit of the face, divided by the greatest height of the clypeus; 5) ocelli-distance ratio: distance from the anterior ocellus to the posterior ocelli (drawing a continuous line on the ventral margin of the two ocelli) divided by the distance between the posterior ocelli.
The terminalia of the holotype of M. lugubris were not dissected and illustrated due to collection policies that do not allow detaching or dissecting parts of primary types; and the male terminalia of O. oxyptera were not dissected due to the fragile condition of the holotype.Non-type specimens of O. flavipleura, compared to the types, were dissected, analyzed and illustrated.For this, the abdomen was detached and treated according to the protocol of CUMMING (1992) and afterwards stored in a plastic microvial containing glycerin.The wing, when necessary, was detached and mounted between cover slips in Canada balsam; the cover slips were glued to a cardboard.The vials with terminalia and wing mounts were attached to the pins of the respective specimens.

Maerorichardia
Diagnosis and remarks.Maerorichardia is the only genus of Richardiidae with mid and hind tibiae thicker than their respective femora (Fig. 5), and the wing with the anal lobe distinctly developed (Fig. 8).Additionally, the only known species of Maerorichardia has the frons densely setulose, the lunule well developed, and the ocellar triangle slightly elongate, with the posterior ocelli not distinctly separated from the vertex (Figs. 3,4), the proepimeral and katepisternal setae robust, the proepimeron and proepisternum bare, and the postmetacoxal bridge not completely sclerotized, the wing entirely microtrichose, and the oviscape distinctly long (Fig. 6), longer than tergites 3 and 4 together.The single described species is only known from the holotype.
Male.Unknown.Diagnosis and remarks.Odontomerella species are small, not exceeding 5.8 mm in length.The compound eye is well developed, occupying most of the head, especially in lateral view, with the gena and postcranium very reduced (Figs. 17,45).The face, in frontal view, is short, with the oral margin distinctly concave (Figs. 18,23,46).The first flagellomere is short, at most 1.8 times longer than high (Figs. 17,24,45).The mid femur lacks spine-like ventral setae, and crossvein rm is inserted proximal to the midlength of cell dm (Figs. 12, 47).
In the identification key provided by HANCOCK (2010), Odontomerella is presented in a dichotomy with Odontomera Macquart, 1843, sharing the occiput much narrower dorsally.However, in our analysis we noticed that the species of Odontomerella do not exhibit this character.The postcranium in Odontomerella is reduced and little wider ventrally (Figs. 17,45), whereas in Odontomera it is developed, distinctly wider at basal two-thirds, especially medially (Fig. 39).Therefore, Odontomerella can be more easily differentiated from species of Odontomera by the combination of features listed above.
However, preliminary results suggest that the short vein is an apomorphic condition within Richardiidae and that these genera form a monophyletic group (L.D. WENDT, unpub.data).
Odontomerella flavipleura is distinguished from O. oxyptera by the following characters: lunule slightly developed; palpus yellow, linear and rounded at apex; scutum and scutellum dark brown almost black, or brown, except lateral region posterior to transverse suture brown or pale brown; postpronotal lobe, notopleuron, and posterior half of anepisternum brown; proepisternum, proepimeron, anterior half of anepisternum, katepisternum, anepisternum and anterior half of meron yellow; fore femur without spine-like ventral setae, with one or two long black preapical setae on posteroventral surface.
Thorax (Figs. 14,15).Scutum and scutellum dark brown, except lateral region posterior to transverse suture, brown.Scutum densely yellowish setulose.Postpronotal lobe, notopleuron, and posterior half of anepisternum brown.Proepisternum, proepimeron, anterior half of anepisternum, katepisternum, anepisternum and anterior half of meron yellow.Posterior half of meron, katatergite, anatergite and mediotergite brown or dark brown.Postmetacoxal bridge brown or pale brown.Postpronotal lobe sparsely yellowish setulose.Postpronotal seta long, black, almost as long as anterior notopleural seta.Proepimeral seta weak.Setae of scutum, scutellum and mesopleuron yellow or pale brown.Dorsocentral setae 2, very long, anterior slightly shorter and thinner than posterior seta; posterior dorsocentral seta and scutellar seta similar in length.Postalar and intra-alar setae very short, almost indistinct from setulae around them.Scutellar seta 1. Legs (Fig. 9).Slender; yellow, except mid and hind tibiae on basal half or third pale brown.Fore femur without spine-like ventral setae; with preapical posteroventral row of long black or brownish setae.Hind femur with weak spine-like setae on apical third or apical fourth of anteroventral surface.Wing (Fig. 12, photo of female non-type material).Yellowish, with large brown spot on apical third.Entirely microtrichose, except cells bm and cu p , and alula.Vein r-m inserted at basal two-fifths of cell dm.Vein M 1 slightly arched posterior to crossvein dm-cu.
Male terminalia.Not observed.Female.Unknown.Holotype male, BMNH: "Odontomerella\det.F. Hendel\ oxyptera,\Hendel" "R.Amazonas\Brasil\H.W. Bates\66.53[label handwritten]" "Amazon.\66.53""Holo\type [white and red circular label]" "HOLOTYPE\ Odontomerella\ oxyptera\ Hendel\verified by\J.E.Chainey, 2002" "BMNH(E)#\ 251412".The collector, Henry Walter Bates, spent 11 years (1848-1859) exploring the rainforests of the Brazilian Amazon (Pará and Amazonas States).However, it was not possible to determine the specific locality and date of collecting of the holotype.The specimen is in bad condition: the posterior part of the thorax (including the scutum, scutellum, subscutellum and mediotergite) was damaged by the pin preventing observation of some sclerites and part of the chaetotaxy.The left wing is missing.The mid and hind legs are glued onto a card below the specimen.
Distribution.Brazil (Amazon River: State of Amazonas or Pará).