Descriptions of two new genera of Maruinini (Diptera, Psychodidae, Psychodinae) from the Mitaraka range of French Guiana

ABSTRACT Little information is available regarding the non-phlebotomine Psychodidae Newman, 1834 of French Guiana. Psychodid specimens were sorted from samples collected during the recent “Our Planet Reviewed” Guyane-2015 expedition in the Mitaraka range. Males and females of two genera of tribe Maruinini Enderlein, 1937, Polletomyia subulata n. gen., n. sp. and Myiomystax trilineata n. gen., n. sp., are described and illustrated. Characters pertinent to assessing relationships among genera of Maruinini are discussed.


Study area
All Psychodidae examined as part of this study were collected during the "Our Planet Reviewed" Guyane-2015 expedition in the Mitaraka range, in the core area of the French Guiana Amazonian Park, organized by the MNHN and Pro-Natura international (Touroult et al. 2018).

ColleCtion and obServation
Most specimens were collected by pan traps (yellow, white or blue pans) while few were also sampled in a Malaise trap or randomly using a sweep net. The biological sampling benefited from the access and benefit sharing agreement "APA973-1", which is reported in each sample label. All specimens were preserved in 70 or 95% ethanol, subsequently macerated in cold 8% potassium hydroxide (KOH), dehydrated in ethanol, transferred to xylene and finally mounted in Canada balsam. Observations and measurements were completed using an Olympus BX50 compound microscope equipped with differential interference contrast, and a Wild M5 stereomicroscope fitted with an ocular micrometer. Drawings were rendered with the aid of a drawing tube on the Olympus system. Photomicrographs were captured using a Nikon DS-Fi1 camera mounted on a Nikon Eclipse E800 compound microscope.
Focus stacks were created using Zerene Stacker (Build T-2018(Build T- -07-19-1515 and images were optimized for color and clarity using Adobe Lightroom® CC and Adobe Photoshop® CS6.

MeaSureMentS
Head width was measured at the point of greatest width of the eyes. Adult head height was measured from the vertex to the anterior margin of the clypeus. Approximate wing length and width were measured at the points of greatest length and width of the dissected wing. Sample sizes are provided before each description with measurements in millimeters presented as a mean followed by a range in parentheses.
terMinology General terminology follows Cumming & Wood (2017), except interpretation of wing venation, which is that of Krzemiński & Krzemińska (2003). Most Psychodidae have hyaline sensilla, variable in shape, inserted on some or all their antennal flagellomeres; these are termed "ascoids" (Kvifte & Wagner 2017). Specific characters of the male terminalia (e.g. gonocoxal apodemes) are described here according to the interpretation of Duckhouse (1990) as followed by Quate & Brown (2004). The elongate lobes articulated posteriorly with the epandrium in Psychodinae are referred to here as "epandrial claspers" sensu Dos Santos & Curler (2014). Both "lateral arm of subepandrial sclerite" and "dorsal paramere" are terms that have not been applied previously for Psychodidae, but are used here provisionally to describe specific parts of the male genitalia.
taxonoMy Specimens examined during this study were identified or determined as new to science based on keys and generic diagnoses provided by Quate & Brown (2004). Nonetheless, the tribal classification used in that work (i.e., Setomimini Vaillant, 1982) is not followed here, as Setomimini is a junior synonym of Maruinini. Duckhouse (1990) provided a diagnosis for Maruinini.

RESULTS
Most of the approximately 400 specimens collected from Mitaraka represent undescribed taxa. Nonetheless, a majority of this material was not included in the present report, but will be treated in subsequent papers. Adequate series of males and females of two undescribed genera of Maruinini were among the collected material, allowing for the following descriptions. etyMology. -This genus is named in honor of Dr Marc Pollet, who collected the type specimens, forwarded them to the author and provided supporting information during the course of this study.
diStribution. -Polletomyia n. gen. is currently known only from the Mitaraka range of French Guiana.
habitat. -Little information regarding specific habitat is available; however, all specimens were collected in lowland rainforest.

reMarkS
The relatively small size of Polletomyia n. gen., as well as their lanceolate wings and dark coloration make it possible to differentiate them in a sample comprised of many psychodid genera and species. These superficial characters also make it possible to associate males and females, as the latter are otherwise lacking in characters that readily differentiate them from other psychodine females. Indeed, if further species of Polletomyia n. gen. are discovered, it may become difficult or impossible to differentiate females within the genus. Despite the relative ease of differentiating them in a bulk sample, accurate diagnosis of this genus is dependent on examination of slide-mounted male terminalia. Currently, the following character states are sufficient for distinguishing this genus from all other Maruinini: male terminalia bilaterally symmetrical; gonostyli each with a conical, spiniform seta inserted apically; tenacula setiform. Nonetheless, additional characters are included above in the diagnosis because they are also unique to the genus, thereby making the diagnosis more robust. Some other genera of Maruinini also have bilaterally symmetrical male terminalia in some or all constituent species (e.g. Alepia, Caenobrunettia, Maruina Müller, 1895, and Myiomystax n. gen.). Yet, each of these groups has a unique build to their aedeagus that is distinct from Polletomyia n. gen. and none of them have conspicuous, spiniform setae inserted at the apices of their gonostyli.
Aside from the male terminalia, some character states present in Polletomyia n. gen. are found as well in other genera of Maruinini, such as a contiguous eye bridge comprised of three rows of ommatidia. These states are also present in Maruina (so far only in subgenus Aculcina Hogue, 1973) and Arisemus Satchell, 1955 and have been indicated by some authors as diagnostic for those genera (e.g. Camico et al. 2019: 298 in their diagnosis of M. (Aculcina)). Despite this, the presence of these character states in multiple genera indicates that they are not diagnostic in and of themselves. Rather, it is necessary to determine whether there are other nuances that distinguish the eye bridge of each genus from others that have the same general appearance. In the case of Polletomyia n. gen., the eye bridge is not particularly distinct, so it is omitted as a diagnostic character.  habitat. -Little information regarding specific habitat is available; however, all specimens were collected in lowland rainforest. Head with vertex extended slightly posteriorly, eyebridge comprised of 3 facet rows, contiguous but slightly constricted at median. Antennae: scape cylindrical, about 1.5 times longer than wide; pedicel globular; flagellomeres fusiform, with paired ascoids on f4 f7, single ascoids on f8 f11. Frons and clypeus distinctly divided; frontal scar patch bilobed posteriorly, contiguous medially. Mouthparts inconspicuous, obscured by clypeus, extending slightly beyond apex of palp segment 1; palpi typical of Psychodinae, with apical segment annulated; palp segment proportions: 1, 2, 2.18, 2.18; labellum about as wide as anterior margin of clypeus. Wing: strongly lanceolate; radial and medial fork positioned at a level basal to the apex of CuA; R 5 terminating in C posterior to wing apex; M 2 incomplete at base; CuA conspicuously widened at base. Male terminalia: bilaterally symmetrical; hypandrium flat, band-like, arched posteriorly, fused with gonocoxites laterally; hypandrium in some specimens appearing folded along median (Fig. 1E); intersegmental membrane connecting between anterior margin of hypandrium and posterior margin of abdominal segment 8, covering base of ejaculatory apodeme; ejaculatory apodeme dorsoventrally compressed at base, dome-like at center, articulating posteriorly with aedeagal sclerites; aedeagus comprised of four blade-like sclerites (Fig. 1E-G) surrounded by a tubular membrane; innermost aedeagal sclerites spathiform, expanding dorsally in extended aedeagus; outer sclerites sinuous, longer than inner sclerites, expanding lateroventrally in extended aedeagus (Fig. 1F); parameres dorsoventrally compressed, flat, with pointed, hook-like projection posteromedially; gonostyli tapered gradually from base to apex, curved ventrally along apical half, appearing pitted ventrally; gonocoxites reniform, about two times as long as wide, setose, with setae alveoli laterally and dorsally; gonocoxal apodemes inflated, triangular in dorsoventral view, bulbous in lateral view, with dorsal paramere extending from posterior margin; subepandrial sclerite narrow, band-like, with lateral arms claw-shaped in dorsoventral view, linked to base of epandrial claspers; epandrium rectangular, narrowing posteriorly; epandrial claspers elongate, tapered, curved dorsally from base to apex, with single, setiform tenaculum inserted dorsoapically. etyMology. -This genus name is derived from the Latin "myia", meaning fly and "mystax", meaning mustache, in reference to the maxillary palps of the male. Before treating the specimens with KOH, the setose palps of male M. trilineata n. gen., n. sp. gave the appearance of the fly having a prominent mustache.
diStribution. -Myiomystax n. gen. is currently known only from the Mitaraka range of French Guiana.
habitat. -Little information regarding specific habitat is available; however, all specimens were collected in lowland rainforest.  In contrast to Polletomyia n. gen., the relatively large size and light coloration of Myiomystax n. gen. make it possible to easily differentiate them in samples containing many psychodid genera. Moreover, while both genera have lanceolate wings, the latter is more distinctive due to several veins being darkly pigmented (Fig. 5). The unique wing of Myiomystax n. gen. also makes it easy to associate males and females of this genus. It remains to be determined whether these characteristics of the wing will be present in the wings of congeners, if any are discovered. Although less important compared to those of Polletomyia n. gen., accurate diagnosis of this genus is still dependent on examination of slidemounted male terminalia.
Myiomystax n. gen. males have a bilaterally symmetrical terminalia, with an aedeagus that extends as an open-close mechanism, much like Polletomyia n. gen. and Maruina. However, they differ from the other genera by having paired aedeagal sclerites as opposed to two pairs (as in Polletomyia n. gen.) or multiple aedeagal spines (as in Maruina). Myiomystax n. gen. males are also unique among these genera in that their gonocoxites lack setae.  etyMology. -The specific epithet is derived form the Latin word "linea", meaning line, in reference to the three darkly pigmented wing veins present in this species.
diStribution. -Currently known from multiple localities in the Mitaraka range of French Guiana.
habitat. -Little information regarding specific habitat is available; however, all specimens were collected in lowland rainforest.

DISCUSSION
Males of Maruinini exhibit geometry in their genitalia that is recognizable among most of the tribe's constituent genera.
In addition to their unique general shape, specific structures such as the ejaculatory apodeme and the gonocoxal apodemes are interlinked in a way that distinguishes them from other Psychodinae. Genitalia morphology most similar to that described and illustrated above can also be found in genera such as Australopericoma Vaillant, 1971(e.g. Bravo 2007: fig. 9), Alepia (e.g. Bravo 2008: figs 8-9), Tonnoira (e.g. Bravo et al. 2008: figs 16-18) and Maruina (e.g. Camico et al. 2019: figs 43, 44). In particular, the "ball and socket" construction, as discussed by Duckhouse (1990), can be identified; however, to see these structures clearly, it is necessary to examine both dissected and whole terminalia in dorsoventral and lateral view. Another interesting character state in both genera described here is the bilateral symmetry of the male terminalia. In most genera of Maruinini, at least the aedeagus and parameres are strikingly asymmetrical; in some species, the gonopods are asymmetrical as well. Exceptions are as mentioned above. Prior to the description of Polletomyia n. gen. and Myiomystax n. gen., Maruina was the only genus of Maruinini of which all described species are known to have symmetrical genitalia. Furthermore, Maruina is the only other genus of Maruinini in which an open and close mechanism involving aedeagal and parameral sclerites has been reported (Vaillant 1963: fig. 2;Camico et al. 2019: figs 43-44).
Specimens of Polletomyia n. gen. and Myiomystax n. gen. collected during this study died with parts of their terminalia fixed in different positions. As shown previously for Maruina, it is evident that the aedeagal and parameral complex has developed into an evertable, or extendable (i.e., open and close) mechanism. Unfortunately, it is unclear how this mechanism works. The movable (i.e., extendable and expandable) nature of the aedeagus in P. subulata n. gen., n. sp. appears to be dependent on the anterior-posterior pivoting movement of the ejaculatory apodeme. As in some other Maruinini, the parameral sclerites appear to serve as a more stationary framework for the opening and closing aedeagus. This indicates that the parameres are serving to stabilize the terminalia in one position while the flies are in copula. Accurate descriptions of these structures depend on being able to differentiate the constituent sclerites. Unfortunately, in many groups of Psychodidae, fusions between the aedeagal and parameral sclerites have apparently occurred, making it difficult or impossible to tease apart these structures. Regardless, these are genus or species-level characters and thus, are of lesser importance for understanding relationships at a higher level. Despite the challenges posed by some characters, others (e.g. ejaculatory apodeme; gonocoxal apodemes) are less ambiguous and can be traced across genera. When ample material is available, Maruinini specimens should be prepared using various methods, such as clearing with cedarwood oil. This method eliminates fat body while leaving musculature intact, which will be necessary to fully understand the structure of the ejaculatory apodeme and how it interacts with the gonocoxal apodemes. This, in turn, could elucidate the process by which the aedeagal and parameral sclerites extend and retract.
Information on Neotropical Maruinini (= Setomimini) was synthesized in part by Quate & Brown (2004), and many species of this group have since been described. Despite this, no phylogenetic revision of the group has been attempted. Many characters of the male and female genitalia are rich in information, but there is a need for clarification of homologies and identification of synapomorphies at higher levels rather than focusing only on autapomorphies found in genera and species.