An illustrated guide for characters and terminology used in descriptions of Phlebotominae (Diptera, Psychodidae)

Phlebotomine (Diptera, Psychodidae, Phlebotominae) taxonomy has been studied extensively, primarily due to the role of these flies as vectors of various parasites, including species of Leishmania, Bartonella and arboviruses that cause diseases in humans and other vertebrates. We present some topics discussed at a round-table on phlebotomine taxonomy held at the Ninth International Symposium on Phlebotomine Sandflies (ISOPS IX) in Reims, France, in June 2016. To date, approximately one thousand phlebotomine species have been described worldwide, although in varying languages and mostly without standardization of characters and terminology. In the interest of standardization, we list the characters that should minimally be considered in the description of new phlebotomine taxa as well as annotated illustrations of several characters. For these characters, multiple illustrations are provided to show some of the variations. The preferred terms for all pertinent characters are listed as well as their synonyms in English, Portuguese, and French. Finally, we offer an updated list of abbreviations to be used for generic and subgeneric names.


Introduction
Phlebotomine (Diptera, Psychodidae, Phlebotominae) taxonomy has been studied extensively, primarily due to the role of these flies as vectors of various agents, including species of Leishmania, Bartonella and arboviruses that cause infections in humans and other vertebrates. To date, approximately one thousand phlebotomine species have been described worldwide, although in varying languages and mostly without standardization of characters and terminology. During the Table 1. Suggestion of the characters and the respective terminology used for the description of a new phlebotomine fly species. L = length; W = width; M = male; F = female; X = include the information.   Figure 1. Dorsal view of the head and its appendages of a phlebotomine female: cl -clypeus; fI -1st flagellomere; fII -2nd flagellomere; hy -hypopharynx; ml -maxillary lacinia; lb -labium; le -labrum-epipharynx; md -mandible; pe -pedicel; pha -pharynx; p1 -1st palpal segment; p2 -2nd palpal segment; p3 -3rd palpal segment; p4 -4th palpal segment; p5 -5th palpal segment; sc -scape; most frequently used measurements: eL -eye length; eW -eye width; clL -clypeus length; fIL -1st flagellomere length; heL -head length; hW -head width; ioD -interocular distance; pL -palpus length -Nyssomyia intermedia.  Ninth International Symposium on Phlebotomine Sandflies (ISOPS IX) held in Reims from June 28 to July 1, 2016 [4], a round-table on Systematics was co-chaired by EAB Galati, P Lawyer, N Léger, and J Depaquit. We report in this paper the results of discussions on the following topics: the use of the informal term sandflies (or sand flies); methods for permanent preservation and mounting of phlebotomine specimens and appropriate places for deposition of type specimens; a recommendation regarding terms used in morphological descriptions of sand flies and their synonyms, illustrated by several drawings with captions; the characters to be used in taxonomic discussion and to be drawn when a new species is described, and some comments about the systematics of phlebotomines and integrative taxonomy.
On the use of the common name sand flies Throughout history, there have been discussions on the use of the popular term sandflies (as one word) or sand flies (two words). Beyond the problem of its true form, this common name has also been applied to other dipterans (e.g. Ceratopogonidae and Simuliidae). Furthermore, some feel that the name does not seem appropriate to the habitat of Neotropical phlebotomine species, whereas others argue that the name was originally given to reflect the color rather than the habitat of these flies. Some colleagues suggested using the term ''phlebotomine flies'' to replace ''sand flies'' or ''sandflies''; others suggested using ''phlebotomine sand flies.'' The discussion ended without achieving a consensus.

On type specimens
In the past and even more recently, phlebotomine type specimens have been deposited in institutions or schools other than museums [1,9,10]. It is very important to deposit at least the holotype in a collection under the supervision of a curator; however, political or administrative changes in these institutions can affect the specimens' preservation and availability under conditions suitable for examination. Consistent with Articles 16C and 72F of the fourth edition of the International Code of Zoological Nomenclature (ICZN), we strongly recommend that authors of species descriptions deposit type and voucher specimens in one or more institutions that maintain a research collection with proper facilities for preserving them and making them accessible for study. It is critical for every institution in which material is deposited to ensure that all name-bearing types are clearly marked and recognizable as such. Moreover, the repository must be capable of taking all necessary steps to preserve these specimens, make them accessible for study, publish lists of name-bearing types in their possession or custody and, in so far as possible, communicate upon request information concerning name-bearing types [6]. In addition to depositing type and voucher specimens, we recommend registration with Zoobank (http://www.zoobank.org)

Methods of preserving phlebotomine specimens
Many type specimens of phlebotomine species and other specimens in many reference collections were mounted in non-permanent media such as Hoyer's Medium or Berlese and have long since deteriorated so that many of the diagnostic characters of the specimens are neither visible nor distinguishable, thereby rendering the specimen useless. It was proposed that a protocol using a permanent medium such as Canada balsam be adopted and standardized, in so far as possible, for preservations of all specimens that are to be deposited in museums for future reference.

Suggested guidelines for the description of new phlebotomine species
Many pertinent characters of Phlebotominae that are currently used for their identification and classification have been described by authors using distinct terminology. This practice has been criticized by other dipterists because, in addition to hindering studies of homology within Phlebotominae, it also makes comparisons among supraspecific taxa difficult. This is particularly problematic for characters of the male terminalia. To this end, we suggest that terminology used in phlebotomine taxonomy be more closely aligned with that used in general dipterology [2,7]. In order to standardize the descriptions and re-descriptions of phlebotomine species, a list of characters (all body parts and their appendages and sensorial structures, such as spines, setae, papillae, sensilla, sutures, etc.) deserving of comment and illustration is proposed (Table 1). Furthermore, in order to contribute to the standardization of terminology for structures that have been frequently used in phlebotomine taxonomic studies, a list is provided ( Table 2) including suggested terms in English and synonyms of these terms that have been used in the past by various authors, in French and Portuguese. Some characters have been infrequently used in published descriptions and may thus be poorly known; for this reason and for the purpose of illustrating the morphological diversity of some characters, drawings have been provided with the corresponding terminology in each legend (Figures 1-28). A drawing is preferable to a photo, but sometimes for structures such as the pharyngeal armature, a photo can supplement or replace a drawing. We posit that the list of characters suggested     permits a detailed description of the species and provides elements for species distinction and phylogenetic studies. Lastly, an update to the previous proposal for abbreviating the names of genera and subgenera [8] is presented in Table 3.

Other taxonomic approaches
It is becoming more straightforward to distinguish phlebotomine taxa using modern techniques. The use of statistical approaches, such as models based on discriminant or multivariate analyses used in morphometric studies, may also contribute to the identification of intra-and inter-specific differences.
Concerning the identification of species using methods other than traditional dichotomous keys, the development of cybertaxonomy may facilitate this task for non-specialists or when many specimens need to be identified. The limited number of characters used by this tool may restrict its application in the case of a diverse fauna on a large scale.
One of the significant challenges facing phlebotomine taxonomists is the adoption of an integrative taxonomic approach, with an increase in attention to identifying characters to be used for accurate and efficient delimitation of species. Well-known, common adult morphological and morphometric characters are important; however, others such as behavioral, biochemical, ecological, and molecular data need to be considered, as well as morphological or develop-mental characters related to eggs, larvae, and pupae. It is highly recommended that markers used in molecular analysis for the delimitation of taxa be standardized and gene sequences should be deposited in free-access databases to permit the analysis of species or populations, especially for widespread taxa. This information is also valuable for phylogenetic studies.   The taxonomy of American phlebotomines has recently been updated regarding the number of described species/subspecies (502: 17 fossil and 485 extant). Additionally, it was commented that there has been an increase of 16.5% in the number of species described since Galati's classification [3] and of 22.5% since that of Young and Duncan [11], though, in this latter case, only for the groups that these authors included in Lutzomyia. It was also commented that some taxa had been resurrected, some other species had been included as junior synonyms and two artificial taxa had been excluded from the species list. It is important to note that Galati's classification has been updated annually and is available on the website: www.fsp.usp.br/~egalati [5].
Finally, the need to strengthen the training of taxonomist groups around the world was emphasized in view of the fact that taxonomy is the basis of the eco-epidemiological studies of vector-borne diseases. In recent years, with the advances of new technologies, particularly the molecular approach, a low level of interest on the part of young researchers in classical taxonomy has been observed that could lead to a significant loss of knowledge because expertise in this field depends on the strength of training and mentorship over successive generations.