The dipteran family Celyphidae in the New World, with discussion of and key to world genera (Insecta, Diptera)

Abstract The family Celyphidae (Diptera, Lauxanioidea) is verified as part of the New World fauna, with a second specimen discovered of a species described from French Guiana in 1844 by P.J.M. Macquart. As this species possesses characteristics that clearly suggest a separate lineage from the Old World celyphids, a new genus is proposed, Atopocelyphus gen. n., with the type species, Celyphus ruficollis Macquart, in the new combination Atopocelyphus ruficollis (Macquart), comb. n. A key to world genera of Celyphidae is presented, along with discussion of generic concepts. Chamaecelyphus Frey is synonymized under Spaniocelyphus Hendel, syn. n., resulting in the following 10 new combinations: Spaniocelyphus africanus (Walker), comb. n.; S. dichrous (Bezzi), comb. n.; S. gutta (Speiser), comb. n.; S. halticinus (Frey), comb. n.; S. kalongensis (Vanschuytbroek), comb. n.; S. ruwenzoriensis (Vanschuytbroek), comb. n.; S. straeleni (Vanschuytbroek), comb. n.; S. upembaensis (Vanschuytbroek), comb. n.; S. violaceus (Vanschuytbroek), comb. n.; S. vrydaghi (Vanschuytbroek), comb. n. The subgenera of Celyphus Dalman are elevated to genus rank, as Paracelyphus Bigot, stat. rev., and Hemiglobus Frey, stat. rev., resulting in the following 17 new and revised combinations: Hemiglobus cheni (Shi), comb. n.; H. eos (Frey), comb. n.; H. lacunosus Frey, comb. rev.; H. pellucidus Frey, comb. rev.; H. planitarsalis (Shi), comb. n.; H. porosus (Tenorio), comb. n.; H. pulchmaculatus (Liu & Yang), comb. n.; H. quadrimaculatus (Tenorio), comb. n.; H. resplendens Frey, comb. rev.; H. rugosus (Tenorio), comb. n.; H. testaceus (Malloch), comb. n.; H. trichoporis (Shi), comb. n.; H. unicolor Frey, comb. rev.; H. violaceus Chen, comb. rev.; Paracelyphus hyacinthus Bigot, comb. rev.; P. medogis (Shi), comb. n.; P. vittalis (Shi), comb. n.


Introduction
The Celyphidae is a small family in the Lauxanioidea (Diptera, Acalyptratae) characterized by their greatly enlarged scutellum and sharp reductions in chaetotaxy. Their gestalt is suggestive of certain metallic chrysomelid beetles. They are known to have their greatest diversity in tropical Asia and Southeast Asia, with a smaller number of species in the Afrotropical Region. The topic of this paper is one of the earliest described species in the group. The species Celyphus ruficollis Macquart, 1844 was the third species described in what is now the family Celyphidae, preceded only by Celyphus obtectus Dalman, 1818 and Celyphus scutatus Wiedemann, 1830. By the end of that century, an additional 14 species had been described (2 of them in an additional genus, Paracelyphus Bigot). Since that time, the family Celyphidae has grown to 115 valid species (of nearly 130 described) within 8 valid genera (of 9 described). Tenorio (1972) is the most comprehensive work on the family, although only dealing with the fauna of the Oriental Region, describing 21 new species-group taxa in addition to redescribing the then-known species in that region. Only 30 additional species have been described in the 45 years since that work.
After the original description by Macquart (1844), Celyphus ruficollis has been rarely mentioned in the literature, and only ever by repeating information from the original description. For example, Bigot (1878) included the species, along with its type locality, in a list of species included in the "Celyphes". Later, in the catalog of celyphids authored by Jacobson (1896), this species is listed as "? C. ruficollis", properly recording it from Guyana gallica (=French Guiana). Given the footnote for this entry ("Secundum figuram cl. Macquarti haec species ob oculos haud prominentes aristamque aliter constructam genus peculiare, Paracelypho affine, constituere videtur." = According to the figure of Macquart this species has eyes that do not overhang the arista so is a different genus built more specifically akin to Paracelyphus), it seems his questioning its inclusion within Celyphus Dalman was only meant to suggest it may represent a different genus more similar to Paracelyphus. The following year, Wandolleck (1897) repeated the list of celyphid species as reported by Jacobson (1896). Later, Frey (1941) suggested that Celyphus ruficollis is likely not a celyphid due to the presence of frontoorbital setae evident on plate 34, figure 4a of Macquart (1844) (Fig. 1), and afterwards, Vanschuytbroek (1952) did not mention the species when listing the species known at that time. Tenorio (1972), in her revision of Celyphidae of the Oriental Region, mistakenly referred to the species as having been described from Australia, and offered no further information. However, this was likely a mix-up with a different species, Celyphus inaequalis Costa, 1864, which was described from "Australia ?", and is, like the current species under study, unknown after its initial description, with the family otherwise not known from the continent of its type locality.
The single syntype of Celyphus ruficollis was collected by François René Mathias Leprieur, during his time collecting in French Guiana (recorded by Macquart as "de la Guyane"). According to Papavero (1971), Leprieur spent much of his life in French Guiana, where he explored as an entomologist, including collections made in Cayenne, and a trip into the interior up the Oyapock River (which forms much of the border between French Guiana and Brazil) in 1832. Although some of his collections survived, much was lost in a shipwreck in 1833. In 1834, Leprieur donated at least 550 insect specimens, including this one, to the MNHN (see remarks below).

Methods
The specimens examined of this New World celyphid were from two collections, as follows: Morphological terminology follows Cumming and Wood (2009). In the description below, the state in the female is given in square brackets [ ] if different from the male, noting that having a single male and a single female for study, differences may be due to simple variation in the species or minor sexual dimorphism, or the remote possibility of being a different species.
Etymology. From Greek, Atopos, meaning out of place, combined with the genus name Celyphus, referring to the unexpected occurrence of this taxon in the New World; masculine.
Diagnosis. This genus differs from all other Celyphidae in having an elongate first flagellomere with a subbasal, plumose arista ( Fig. 13), and in having abdominal tergites 5 and 6 each subdivided or creased medially with a strong triangular notch along each posterior edge in both sexes (Figs 18,20).
Remarks. The other celyphid genera have a much shorter first flagellomere with a subapical arista that is pubescent and often expanded and leaf-shaped in the basal 1/3 (see Fig. 29). The abdominal tergites are sometimes subdivided (i.e., in Spaniocelyphus), but this is always tripartite, with a central section and two lateral sections (Fig. 31); otherwise, the tergites are undivided (Fig. 28). With regards to other dipteran families in the Neotropics with superficially similar genera, Celypholauxania Hendel (Lauxaniidae) and Peltopsilopa Hendel (Ephydridae) share a characteristically enlarged scutellum, although none to the extent of the Celyphidae. One of the species currently in Peltopsilopa had been originally described as a species of Celyphus (Savaris et al. 2016), and other genera (outside the New World) had also been originally described as celyphids, such as Afrocelyphus Vanschuytbroek, now considered a junior synonym of Nomba Walker (Chloropidae).
Wing (Figs 12, 16). Wing length [4.2-] 4.5 mm, height [2.0-] 2.1 mm; sapromyziform, with spinules on costa ending at tip of R 2+3 ; hyaline, but darkened brown basally and within costal cell, subcostal cell, and along costal vein to point between apices of R 1 and R 2+3 , along vein R 2+3 except apical 1/4, and with some slight darkening on R 4+5 and crossvein r-m; veins brown except yellow on distal half of costal vein and distal parts of veins R 2+3 , R 4+5 and M 1 ; costal vein ends at apex of M 1 ; crossvein r-m slightly beyond midpoint of discal cell; CuA 1 short, 1/5 length of crossvein dm-cu, not reaching wing margin; A 1 +CuA 2 short; A 2 present only as darkened fold. Halter brown.
Female terminalia. Hypoproct orange, longer than wide, rounded distally, covered with pale brown setulae. Epiproct brownish, short, rounded distally, covered with dark setulae. Cerci orange, slightly longer than wide, with mixed pale and dark brown setulae, a few elongate.
Remarks. Crosskey (1971) discusses in detail the labeling standards in the Macquart collection, which are directly applicable to this specimen (Fig. 2). The circular label is green on one side, meaning it is from the Americas, and the handwritten number on the white side is the accession number, which represents the MNHN serial number given to the collection to which the specimen formed a part, and the year of accession, in this case 2896 / 34 (serial number 2896, year of accession 1834). This accession number is found in the accessions book at the MNHN (Fig. 3), titled "Catalogue des Animaux articulés Crustacèa, Arachnidea, Insectea, reçus, donnés échangés ou achetés comprenant les années 1826 à 1834. Tome I." Within this catalogue is the line for accession number 2896 in the "Série 1834", as follows (columns separated by "/"): Insectes donnés / par M r F.R.M. Leprieur d'un voyage fait en / Amérique / 550 [specimens]. As discussed by Crosskey (1971), Macquart's type labels did not consistently indicate "n.sp." (or similar) at the time of this publication, although he did start to consistently use this term on his labels after this time. Noting that the label is slightly ripped at the bottom of the first number of the year, it is likely that this was accessioned in 1834, which is consistent with the types of the muscids Limnophora elegans Macquart and Spilogaster maculipennis Macquart, both collected by Leprieur "de la Guyane" from the same publication (Macquart, 1844). There is also reference in Pont (2012), but not Crosskey (1971), to an old handwritten 3 digit number label for the two preceding species, and the type of Celyphus ruficollis similarly has such a number label, 535. The handwriting on these labels is clearly that of Macquart, in comparison with labels presented by Crosskey (1971) and Pont (2012), and other Macquart specimens in the MNHN seen by the author. It is possible that this number represents a sort of "unique identifier" of the time, given that the Catalogue indicates 550 specimens were donated (i.e., that this was specimen 535 of 550). Another alternative is that the number was a reference to the species itself (i.e., that this number was a reference to Macquart's notes on this species, although no such notes have been located). In any case, the meaning of this secondary number remains a mystery.
It is worth noting that Macquart's description at least partly contradicts his figure 4a (plate 34) (Fig. 1), in that the description states that the arista is inserted near the tip (i.e., subapical, as is typical of all other celyphids), while the figure shows the arista as clearly subbasal. Unfortunately, the type specimen has lost the first flagellomere and arista, and given that the condition of these structures is important to the definition of this new genus, a further comment is warranted. In the newly collected specimen, the antennae are quite elongate, well beyond that of any other Celyphidae, and the arista is plumose and placed subbasally, all unique states in this species relative to other celyphids. Macquart (1844) does not mention an elongate antenna, and his figure 4a (plate 34) (Fig. 1) does not show an antenna of such length, but it does show the subbasal placement and the plumose condition of the arista, so it remains a possibility that the first flagellomere itself was broken (i.e., appearing short) when Macquart examined the specimen, and only later completely broke off and was lost. Also note, neither the type specimen nor the new specimen possess what appears to be the fronto-orbital setae pictured in figure 4a (plate 34) (Fig. 1). This is significant because Frey (1941) specifically refers to this figure to point out that this species is likely not a celyphid due to the presence of these setae.