New species and morphological notes on the termitophilous genera Fonsechellus Silvestri and Oecidiophilus Silvestri from Brazil (Staphylinidae, Aleocharinae, Corotocini, Termitoceina)

Fonsechellus Silvestri and Oecidiophilus Silvestri consist of two Neotropical genera of termitophilous rove beetles, which have been poorly characterized due to the scarcity of material for studies. Herein, based on material collected in the seventies and housed in the Museu de Zoologia da Universidade de São Paulo, two new species associated with Atlantitermes guarinim Fontes and Diversitermes  sp., are described and illustrated: Fonsechellus heterosetosus sp.  nov. and Oecidiophilus cleidecostae sp. nov., respectively. The latter represents the first record of the genus to Brazil. Also, Fonsechellus fragilis and F. fontesi are redescribed, and a key for species identification is provided for the genus. The condition of the membranous wings of Fonsechellus is addressed and discussed, and the definition of both genera is expanded. Key-Words. Termitophily; Neotropical; Rove Beetles; Chaetotaxy; Wing Loss.


INTRODUCTION
The subtribe Termitoceina was established in a monograph on Corotocini by Jacobson et al. (1986) to group six genera presenting tarsal formula 5-5-5 and barely sclerotized paratergites, and also having the same generalized head and thoracic features found in the subtribe Abrotelina. These six genera were established by Silvestri, mostly in a paper published in 1946 (Fonsechellus, Mormellus, Oecidiophilus, Parvidolum and Perlinctus), and Termitoiceus, in an earlier paper (Silvestri, 1901).
Historically, the relationships among the Termitoceina genera were surrounded by uncertainty due to the scarcity of material for dissection, resulting in the lack of detailed morphological studies. The genus Fonsechellus Silvestri, 1946 was established along with the description of two species: F. bicolor and F. diversicolor. The author also divided the genus into two subgenera (Fonsechellus s. str. and Trianellus) based on the ratio of head length and width, their head chaetotaxy, and also on the presence or absence of geniculate bristles on sternites. Later, Seevers (1957) described Fonsechellus fragilis, also provid-ing morphological notes on the genus, redescription of the two former species and a key for their identification. Seevers (1957) criticized the previous division of the genus Fonsechellus and pointed out that the characters provided by Silvestri (1946) did not justify the establishment of the subgenera. Even though not explicity informed, Seevers treated Trianellus and Fonsechellus as possible synonyms. Nonetheless, Seevers did not provide further details about the problems of Silvestri's characters, and later on, Kistner (1993) interpreted Seevers' approach as if he had in fact synonymized Trianellus with Fonsechellus. Kistner, in the same paper, described Fonsechellus fontesi based on specimens collected and sent to him by LR Fontes. Kistner (o. c.) also provided keys for species and a hypothesis of relationships for most genera of the subtribe.
Oecidiophilus Silvestri, 1946 is a more enigmatic genus represented by only one species, Oecidiophilus mimellus Silvestri, 1946, from Loreto (Misiones, Argentina). No subsequent information has been published due to rarity of this species in collections.
Herein, a new species of Fonsechellus, F. heterosetosus sp. nov. is described, and F. fragilis Seevers, 1957 andF. fontesi Kistner, 1993 are redescribed. A key for species identification is also provided. Additionally, a second species of Oecidiophilus, O. cleidecostae sp. nov., is also described. This species represents the first record of the genus for Brazil, expanding its geographical distribution. This new species is rather distinct, supporting its taxonomic validation, but known by only one specimen from Brazil, Minas Gerais (Belo Horizonte) and a more detailed description is impossible without proper dissection.

MATERIAL AND METHODS
Dissection and illustration procedures follow Zilberman (2018), with adaptation on specimens mounting on slides, now with glycerin jelly. Terminology follows Jacobson et al. (1986) for external and internal morphology and Sawada (1972) for chaetotaxy of sternite VIII, labrum and postmentum, with the following modification to postmentum chaetotaxy: although the three main bristles approached by Sawada were definitely present, it was not possible to have the homology inferred. Thus, we decided to use an alternative, provisory terminology based on the length of bristles: long (l), medium (m) and short (s).
The specimens studied are deposited at the Museu de Zoologia da Universidade de São Paulo (MZSP).
Diagnosis: Physogastric and small species, usually less than 2 mm long, sclerotized parts reddish-brown to pale yellow, paratergites separated and barely sclerotized. Tarsal formula 5-5-5, two spurs at apex of anterior tibia and one at apex of median tibia. Tergites sclerotized into rectangular bands and sternites poorly sclerotized, and sides of third or fourth to sixth sternites with dense clusters of bristles, geniculate in some species. Chaetotaxy of pronotum and abdomen with interspecific variation in size and density; also variable between male and female in some species.
Redescription: Head slightly longer than wide, widest right before the eyes; gula straight; foramen magnum less than 2.5 times the head width; eyes circular in shape; front impressed; antenna with 11 antennomeres: scape elongate, antennomeres II-X subquadrate, XI oblong, with proximal margin transverse. Mentum fused to submentum (postmentum), subtrapezoidal, lateral margins evenly round; position of the three main bristles near apex variable interspecifically. Prementum subquad-rate, labial palpi with 3 palpomeres, ligula broad, bilobed apically in most species. Mandibles asymmetrical; right mandible with longitudinal row of small teeth on cutting edge; both mandibles bear a median tooth, conspicuously larger on left mandible, and a drop-shaped sulcus on lateral margin. Maxillae with stipites longer than wide, each bearing three long bristles: two on posterior region on either side next to cardo, and another next to the palpifer; galea about as long as lacinia, subquadrate with many short bristles; palpi with 4 palpomeres, first palpomere small, subquadrate; second palpomere elongate and about three times longer than the second; third palpomere slightly longer than the second; fourth narrow, about twice as long as the first. Labrum transverse in most species, with p1, m2-m1 and at least one bristle of d row present; most species with conspicuous pairs of median rows of bristles.
Thorax: Pronotum about as long as wide, widest on anterior margin, which is slightly convex; chaetotaxy variable. Wings present and broken. Elytra setose, about 1.5 times longer than wide and lateral margins straight in most species. Mesosternum slightly shorter and narrower than metasternum; endosternite with slender arms, about 1.5 times longer than the base. Legs well developed; anterior tibia with two internal apical spurs and median tibia with one.
Abdomen highly physogastric with generalized pattern shape; segment I with a narrow tergite with medial margin projected backwards; segment II with one tergite and paratergites, the latter as sclerotized diagonal bands; paratergites of remaining segments barely sclerotized. Segments III-VIII each with complete tergite and sternite; tergites expanded posteriorly with secondary sclerotization; sternites represented by weakly sclerotized bands, sometimes barely visible; rows of bristles present on tergites and sternites, with length varying between species or even between male and female within a same species; sternite VIII wider than long, with six main bristles: a row of four bristles on median region and another row with two; the distance between the two rows vary between male and female, being closer in the latter; tergite VIII subquadrate, with two pairs of long bristles on median region (a2-a1), three to four pairs of medium-sized bristles present apically (p3-p2-p1/ p4-p3-p2-p1); distance of each side a1 bristle vary between male and female, being closer on the latter; sternite IX in females divided into two slender pieces attached to margins of tergite IX; sternite IX in males in one piece shovel-shaped apically and variable chaetotaxy among species; tergite IX with long apodemes in males and many small-medium size bristles; a distinct long bristle is present in most species; tergite X subquadrate with chaetotaxy variable, two pairs of long bristles on either side and a central bristle of same size is a condition present in most species. Aedeagus bulbous with shape of median lobe apex variable in some species. Spermatheca with capsule and stem sclerotized, shaped similarly among species.
Remarks: Fonsechellus species are often compared to those of Termitoiceus (Silvestri, 1901;Seevers, 1957;Kistner, 1993) due to overall body shape. Silvestri (1901) distinguished members of Fonsechellus in having a bilobed ligula, macrosetae on tergite IX and geniculate setae on sternites IV-VII. Additional differences from Termitoiceus pointed out by Kistner (1993) are related to the shapes of the labial palps, pronotum, elytra, meso-and metasternum, meso-and metanotum, mandibular teeth, galea, tarsi, and sclerotization of tergites and paratergites, as well as the shape of lateral lobe of aedeagus and connection of gland reservoir of abdominal segment VII. The degree of sclerotization of tergites, sternites and parategites, mild in Fonsechellus and heavy in Termitoiceus, is probably the most conspicuous difference at first glance. Some species of Fonsechellus do not have geniculate bristles on sternites, bilobed ligula or macrosetae on tergite IX. The presence of mandibular sulcus on lateral margin, longitudinal row of small teeth present near apex of right mandible, sexual dimorphism of chaetotaxy (a1 bristles) of tergite VIII, and shovel-shaped apex of sternite IX (male), could be considered as generic characteristics, but a broader study of other genera in Termitoceina is needed for confirmation. Other characteristics present in most species (except F. fontesi, discussed later in this paper) are bilobed ligula, distinct macrosetae on tergite IX and conservative chaetotaxy for tergite X.
Diagnosis: Sclerotized parts light yellow, labrum not swollen; male and female scarcely setose, with short bristles on abdomen; pronotum of male and female with only four primary bristles.
Redescription: Head almost as long as wide, widest just behind the eyes (Fig. 5), with scattered bristles on dorsal and ventral views, and a pair of long bristles on dorsal posterior region. Labrum transverse, about 1.7 times wider than long, not swollen in lateral view; bristles d2/ m2-m1/p1 present in male and female, d1 present in female; three pairs of bristles present on the longitudinal-medial region of labrum, one of which, near base, is absent in female (Figs. 10, 67). Mentum with four bristles each side, three reconizable primary bristles, near apex, long (l), medium (m) and short (s), distributed as follows: m on anterior region, followed by l located next to the sides, out of the longitudinal row of m; and more posterior, s located on longitudinal row of m; a short bristle located between m bristles is present on female (Fig. 68).
Thorax: Pronotum with four primary bristles, two on anterior margin and two on disk near apex, these closer to each other than the marginal pair; elytra slightly elongate; considering the widest and longest measurements, about 1.3 times as long as wide (Fig. 13).
Abdomen with short bristles in male and female (Figs. 1-4); tergite VIII with two pairs of transversally misaligned long bristles on median region (a2-a1), three pairs of medium sized apical bristles (p3-p2-p1) and a similar-sized pair present between the median and apical row of bristles (Figs. 20,73,74); sternite VIII with three pairs of transversally misaligned primary long bristles on median row and two long bristles centered next to apex (Figs. 18,19,75,76); sternite IX in females divided into two slender pieces attached to each margin of tergite IX (Fig. 21); sternite IX in males with apex enlarged; three apical primary long bristles, and two shorter bristles more distant from apex (Fig. 22); tergite IX with many medium-sized and short bristles, and one long and one very long bristles; tergite X with two pairs of long bristles on either side and a central bristle of same size (Fig. 21). Aedeagus with median lobe apex not extended anteriorly on dorsal region (Figs. 23, 64).
Remarks: Seevers (1957) compared this species with F. bicolor, from which is distinguished by the chaetotaxy of pronotum (four bristles instead of ten) and the presence of non-geniculate bristles on sternite VI. Probably, the most conspicuous character to differentiate F. fragilis from F. bicolor is the presence of short bristles on the abdomen of the former species, whereas they are mostly long in the latter. It is noteworthy that the information in Kistner's (1993) key that F. fragilis has geniculate bristles is incorrect. In the key, the number of bristles on the pronotum of F. bicolor is said firstly to be eight, but in the following line, when the chaetotaxy is detailed, the total is precisely ten, even though the correct number is 12 (Silvestri, 1946, see fig. 8).
Although the tergites seem to have three pairs of primary bristles on apex (p3-p2-p1), similarly to Fonsechellus heterosetosus sp. nov., there is an additional pair of medium-sized bristles (same size of p row bristles) located between a and p rows. This last pair is possibly homologous to the fourth bristle (p4) of F. fontesi, with the difference that in the latter it is aligned to the other bristles of the same row. (Figs. 25-43, 65, 69, 70, 78-82) Fonsechellus fontesi Kistner, 1993: 204. long as wide; all primary bristles located on posterior region, which is projected upwards due to the truncated and swollen appearance of its attachment with head; one bristle of d complex located on postero-central region; from apex to line of d bristle, p1-m1-m2 are evenly distributed on margins (Figs. 25,26,32,69). Mentum with four bristles each side, three recognizable primary bristles, near apex, longitudinally aligned on margins, as follows: medium (m), long (l), short (s) (Fig. 70).

Fonsechellus fontesi Kistner
Thorax: Pronotum similar to F. fragilis, with four bristles in male and female; elytra elongate: considering the widest and longest measurements, it is more than 1.6 times as long as wide (Fig. 36).
Abdomen with long bristles in male and female ; tergite VIII with two pairs of transversally aligned long bristles on median region (a2-a1), and four pairs of midsized apical bristles (p4-p3-p2-p1) (Figs. 39,78,79); sternite VIII with three pairs of transver-sally aligned primary long bristles on median row (slightly misaligned in female) and one pair of long bristles centered below (Figs. 37,38,80,81); sternite IX in females divided into two slender pieces attached to each margin of tergite IX; sternite IX in male with posterior region slender, with four long apical bristles and one shorter above (Figs. 41,82); tergite IX with many medium and short bristles; long and very long bristles absent; tergite X with three apical long bristles (Fig. 40). Aedeagus with median lobe apex extended anteriorly on the dorsal region (Figs. 42, 65). shaped and swollen labrum, easily distinguish it from any other species of Fonsechellus. Fonsechellus fontesi has the majority of common characters of the genus: shape of the median teeth of the mandibles and asymmetrical size of left and right mandibles; right mandible with a longitudinal row of small teeth; drop-shaped sulcus on the lateral margin of the mandibles; presence of spurs on the anterior and median tibiae; sexual dimorphism in the chaetotaxy of tergite VIII; and shovel-shaped apex of male sternite IX. Other characteristics that distinguish it from the other species include the labrum almost as long as wide and with distinct chaetotaxy, tergite X with only three apical primary bristles, tergite IX without long bristles, and the male sternite IX with a narrow posterior region.
For now, we have decided to maintain F. fontesi in the genus, but future detailed studies on related genera may provide more evidence for transferring the species to a new genus.
Diagnosis: Sclerotized parts reddish-brown; labrum not swollen; bristles on abdomen long on female and short in male; pronotum of female with 12 bristles, and male with four.
Description: Head almost as long as wide, widest right behind the eyes. Labrum transverse, about twice wider than long; not swollen in lateral view; d2-d1/m2-m1/p1 present in male and female; three pairs of bristles present on the longitudinal-median region of labrum; first pair on posterior region absent in female (Figs. 51,71). Mentum with four bristles each side, three primary bristles, near apex, long (l), medium (m) and short (s), distributed as follows: l on antero-angular region, s on central-apical of same transversal row, region; m present behind and between l and s (Fig. 72).
Thorax: Pronotum with four primary bristles in male, two near anterior margin and two on disk near apex; discal bristles closer to each other than the anterior pair; 12 bristles in female, as follows: two pairs on anterior margin near apical angle, two pairs on either lateral margin, one subapical pair and another pair near base; elytra slightly elongate: considering the widest and longest measurements, it is about 1.3 times as long as wide.
Abdomen with bristles short in male and long in female ; tergite VIII with two pairs of transversally misaligned long bristles on median region (a2-a1) (slightly aligned in male), three pairs of medium bristles at apex (p3-p2-p1) (Fig. 59); sternite VIII with three pairs of transversally misaligned primary long bristles on median row and two long bristles centered below ; sternite IX in female divided into two slender portions attached to each margin of tergite IX (Fig. 60); sternite IX in male with apex enlarged, with four long bristles on apex and three shorter above (Fig. 61); tergite IX with many medium and short bristles, and one long and one very long bristle; tergite X with two pairs of long bristles on each side and a central bristle of same size (Fig. 60). Aedeagus with median lobe apex not extended anteriorly on the dorsal region (Figs. 62,66).