Glemparon Jaschhof 2013
Creators: name: Jaschhof, Mathias
name: Jaschhof, Catrin
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Cecidomyiidae
Glemparon

description: Genus Glemparon Jaschhof, 2013
Diagnosis
Glemparon is known only from males; females and larvae remain unrecognized. Unprecedented within Dicerurini, the number of flagellomeres varies among different species of Glemparon from 12 to 18, as far as is known. Basitarsal spines are either present (Fig. 1A) or absent (Fig. 1B), which is another unusual case of intrageneric variation. Genitalic structures show the following synapomorphous characters, with four or more present in a single species: (1) the gonostylar apex is laterally compressed (Fig. 2B); (2) the gonocoxites have a posteromedial protuberance, which is largely membranous (and thus hard to study by light microscopy) and usually structured in complicated ways (Fig. 2A; see remarks below), and (3) extensive membranous areas ventroposteriorly below the gonostyli (Figs 2A, 4A); (4) the tegmen is provided with a pair of posterolateral processes that are mostly serrate or tubercular (Fig. 15C) and (5) with a pair of elongate apodemes (Fig. 15C; called here the longitudinal apodemes, equal to the ventral processes by Jaschhof & Jaschhof (2013: fig. 64A); see remarks below); (6) the ejaculatory apodeme is invariably single-pointed and mostly arrow-shaped (Fig. 3C); (7) the posterior edge of the ninth tergite, which is convex (as opposed to concave or bilobed), is mostly provided with megatrichia (Fig. 6D; see remarks below).
Other characters
As our present study reveals, G. sagittifer is the only species of Glemparon whose postfrons and metepisternum are setose; in all the congeneric species those sclerites are devoid of setae. Therefore, the presence of pronotal and metepisternal setae cannot be regarded as generic characters (see Jaschhof & Jaschhof 2013). The flagellomeral necks are shorter (Fig. 1H) to several times longer (Fig. 1F) than the nodes. Circumfila, which are present on all but the terminal flagellomeres, have posterior extensions only on the proximal flagellomeres; those extensions, which have different lengths, are either closely adpressed (Fig. 1F) or free-ended (Fig. 1G). In species with generally short extensions, some of the circumfila are simply ring-shaped or sinuous (Fig. 1H). The flagellomeral nodes are completely covered with microtrichia, while the necks are always glabrous. The palpus of G. sagittifer was described to have only two to three segments (Jaschhof & Jaschhof 2013), whereas the conspecific specimen described in the present paper has four segments. The four-segmented condition is found, invariably, in all other species of Glemparon, but both the lengths and shapes of palpal segments are subject to variation, both among different species (see Fig. 1C vs Fig. 1D) and within one and the same species (see Fig. 1D vs Fig. 1E). Pronotal setae are either present or absent. The claws of Glemparon are subrectangular rather than evenly bent, with the distal sections clearly longer than the basal sections, and with one large and two to three small teeth basally.
Remarks on certain genitalic structures
The structure called here the posteromedial protuberance possibly indicates the presence of the ninth sternite, which in the basal subfamilies of Cecidomyiidae, including Porricondylinae, is thought to be merged, mostly untraceably, into the ventral gonocoxal bridge (see Jaschhof & Jaschhof 2013). Protuberances similar to that found in Glemparon are also present here and there in other Dicerurini, such as Dicerura complicata Spungis, 1987; D. adunca Borkent, 1990; and Linnaeomyia hortensis Jaschhof & Jaschhof, 2015; but only in Glemparon do they have an elaborate structuring. As a matter of fact, Porricondylinae show quite a variety of different modifications at the base of the ventral gonocoxal emargination, many of which might be derived from the ninth sternite; examples are the gonocoxal processes of many Porricondylini (Jaschhof & Jaschhof 2013: fig. 98B) and different kinds of abnormal vestiture found throughout the subfamily (Jaschhof & Jaschhof 2013: fig. 155A). In many Glemparon the posteromedial protuberance appears to be connected to either the apex of the ejaculatory apodeme or the tegmen, or both; however, their mostly membranous texture and small size makes these connections difficult to study using light microscopy.
The longitudinal apodemes arising from the tegmina of many Glemparon are, to our knowledge, unique within the Dicerurini. They arise, as far as one can discern, from the bases of the posterolateral processes, and either end freely or connect to the inside of the gonocoxal wall. Due to the muscles attached to them, these apodemes are quite conspicuous in our specimens, but one cannot be sure about their visibility in macerated specimens where they possibly become eliminated together with the muscle tissue.
The integumental projections referred to here as megatrichia are conspicuously enlarged microtrichia, which appear to be flattened and bent apically. Megatrichia are unknown to us in other Porricondylinae, including Dicerurini. In Glemparon, they are situated next to ordinary, hair-like microtrichia as well as tubercle-like microtrichia (Fig. 14B), which, within Dicerurini, are found also on the ninth tergite of several Dicerura (e.g., Jaschhof & Jaschhof 2013: fig. 54A). In Porricondylinae, as in other fungivorous Cecidomyiidae, the phenotypic variation of microtrichia is insufficiently studied.
Relationships to other Dicerurini
Male morphology suggests that Glemparon is the sister group to Dicerura. In both genera the gonocoxites are provided with ventroposterior lobes (referred to as gonocoxal processes by Jaschhof & Jaschhof (2013)), which we interpret here as a synapomorphy. The same kind of gonocoxal lobes are present here and there in other Dicerurini, but the few species concerned have genitalic structures that otherwise are very different from that in Glemparon and Dicerura. While there is always a single pair of gonocoxal lobes present in Glemparon, Dicerura may have either one or two pairs. Another derived trait shared by the two genera is the presence of modified microtrichia on the ninth tergite. Apart from large, coarse microtrichia the size of setulae that are commonly found in both genera, many Dicerura have coniform, tubercle-shaped microtrichia, whereas many Glemparon have megatrichia. A third similarity in genitalic characters is that the gonostyli of both groups have exposed, densely microtrichose areas, which in Glemparon are situated at the gonostylar apex but in Dicerura at the gonostylar base (“mediobasal lobe”, see Jaschhof & Jaschhof (2013)). Very few Glemparon have microtrichose bulges at the gonostylar bases, but then in a dorsal, not medial, position. Despite the fact that areas of dense microtrichia are exposed in different positions on the gonostylus – apical in Glemparon, basal to medial in Dicerura – their presence might be another indicator of the common ancestry of both genera. Indicative here are the short, blunt-ended bristles situated among the microtrichia in both Glemparon and Dicerura; those bristles are typically located at or near the gonostylar apex (not only in Dicerurini and other Porricondylinae but throughout the fungivorous subfamilies of Cecidomyiidae). It therefore stands to reason that the mediobasal lobe found in Dicerura is actually the gonostylar apex. If so, Glemparon and Dicerura concur in having exposed areas of dense microtrichia intermingled with a few short bristles at the gonostylar apex. To end on another interesting note, two species of Dicerura with structures similar to the gonocoxal posteromedial protuberance found in Glemparon, namely D. complicata and D. adunca, are so aberrant also in other genitalic characters that one might doubt the validity of their current generic placement. However, both species are characterized as true Dicerura by the possession of a bifurcate ejaculatory apodeme, which is the character distinguishing Dicerura from all other Dicerurini, including Glemparon.
Identification of species
Males of Glemparon can be identified to species using genitalic characters. Each of the 19 species known to date is distinguished by a specific design of either the tegmen or the gonocoxites. Even so, we usually refer to three different structures – usually gonocoxites, gonostylus and tegmen – when diagnosing species, for there is every indication that similar-looking species of Glemparon exist that might be found in the future. Illustrations can describe those structures best and scanning them is, in our estimation, the most effective way to identify these taxa. For the same reason we refrain here from presenting a key. The present study, though based on only one to three specimens per species, revealed that non-genitalic characters tend to vary intraspecifically, such as the number of flagellomeres and the outline of palpal segments. Consequently, such characters should be used with caution until the extent of variation is better known.
description: Published as part of Jaschhof, Mathias & Jaschhof, Catrin, 2018, Descriptions of eighteen new species of Glemparon, a previously monotypic genus of Porricondylinae (Diptera, Cecidomyiidae), pp. 1-38 in European Journal of Taxonomy 450 on pages 3-5, DOI: 10.5852/ejt.2018.450, http://zenodo.org/record/3813931