A new case of an Holarctic element in the Colombian Andes: first record of Cordyla Meigen (Diptera, Mycetophilidae) from the Neotropical region

Abstract Three new species of Mycetophilidae – Cordyla monticola sp. n., Cordyla pseudopusilla sp. n. and Cordyla reducta sp. n. – are described from the Colombian Andes, representing the first described species of Cordyla Meigen from the Neotropical region. Colour photos of their habitus, wing and terminalia are provided. The morphological affinities of male terminalia are discussed in a worldwide context. The distributional pattern of the genus clearly indicates a case of northern elements reaching the north-western region of the Neotropics that corresponds to a secondary extension of a Holarctic clade to the south.


Introduction
Members of the monophyletic genus Cordyla Meigen, 1803 are well distinguished among fungus gnats (Diptera: Mycetophilidae) because of their considerably small size, strongly humpbacked habitus, reduced number of flagellar segments and swollen antepenultimate segment of palpus. The latter character is unique within fungus gnats worldwide, enabling immediate recognition while working with collections on the genus level.
Further identification of the species is based on several body-characters with emphasis on the number of flagellomeres, and colour and length of the swollen palpal segment. However, as usual, the most important set of the species level morphological characters is that of the male terminalia. According to their structure, the genus has been divided into three subgeneric groups as defined by Kurina (2001). Tuomikoski (1966) transferred Cordyla to the tribe Exechiini within which it has a rather isolated position (Rindal et al. 2009, Ševčík andKjaerandsen 2012).
Thirty-nine species are described in the limits of the genus so far, viz. twenty-four from the Palaearctic region, ten from the Nearctic region, three from the Oriental region and two from the Australasian region (Kurina and Oliveira 2013 and references therein). From undescribed species, the genus has also been known in the Neotropical region (Oliveira et al. 2007, Vockeroth 2009, Kurina and Oliveira 2013.
Over recent years the junior author has accumulated Cordyla specimens collected in Colombian Andes. The aim of this paper is to describe, illustrate and discuss three new Cordyla species from that material representing the first named species in the Neotropical region.

Material and methods
All material was collected with Malaise traps from the Colombian Andes at an altitude greater than 1900 m a.s.l. from 2001 to 2003. The collecting was performed during "The Colombian Arthropod Project (CAP)" -a collaborative arrangement between the Humboldt Institute in Villa de Leyva, Colombia, the University of Kentucky, and the Natural History Museum of Los Angeles County (LACM) -funded by U. S. National Science Foundation (NSF DEB 9972024) and the Humboldt Institute (see also http:// www.sharkeylab.org/biodiversity/static.php?app=colombia&page=index). The material herein studied was collected from three protected areas of Colombia (see also http:// www.parquesnacionales.gov.co/ and Fig. 38) as follows: 1) the "Parque Nacional Natural Farralones de Cali" ("PNN Farralones de Cali" within the label data) located on the West Cordillera and characterized by a great variety of climates that are reflected in a variety of ecosystems, as cold regions with paramillos and its diverse vegetation, warm areas with plants with tabular roots and reaching considerable heights, and temperate areas with oaks and black oaks; 2) the "Santuario de Flora y Fauna Otún Quimbaya" ("SFF Otún Quimbaya" within the label data) characterized by evergreen sub-Andean jungle vegetation, in which the effect of the rainy and dry seasons is masked by the usual presence of mist formations and there is gradual replacement of low synchrony in the production of fruits and leaves, and is located on the West Cordillera, and 3) the "Santuario de Flora y Fauna Iguaque" ("SFF Iguaque" within the label data) locating on the East Cordillera, in a region of paramo and Andean forest ecosystems, including a representative sample of oak forest.
The examined material was initially stored in ethyl alcohol, within which most specimens -after study under a stereomicroscope Leica S8APO -are still preserved.
In case of several specimens, for more detailed study of male terminalia, they were detached and macerated in a solution of KOH, followed by neutralization in acetic acid and washing in distilled water. The remaining chitinous parts were thereafter inserted into glycerine for study including illustrations and preserved as glycerine preparations in polyethylene microvials (cf. Kurina 2003). A few specimens including their terminalia were slide mounted in Euparal following the method described by Hippa and Kurina (2012). The preservation method of each specimen is indicated in the material section. The measurements are given as the range of measured specimens followed by the mean value, while the measurements and setosity information from the holotype are given in square brackets. The ratios of the three apical palpal segments are given as 3 rd :4 th :5 th . All measurements are taken from specimens in alcohol. Morphological terminology follows generally that of Søli et al. (2000) and Amorim and Rindal (2007) while the interpretation by Kjaerandsen (2006) and Oliveira and Amorim (2012) are used for terminalia and thorax, respectively.
The habitus photos have been made in an alcohol medium and combined by software LAS V.4.5.0. from multiple gradually focused images taken by a camera Leica DFC 450 attached to the stereomicroscope Leica M205C. The photos of terminalia were combined by the same software but the camera was attached to the compound microscope Leica DM 6000 B (see also Kurina et al. 2015). Adobe Photoshop CS5 was used for editing the figures and compiling the plates.
The distributional map was performed with the software DIVA-GIS 7.5.0 (http:// www.diva-gis.org/) and edited with Adobe Photoshop. The shapefile maps from Colombia and South America were obtained from DIVA-GIS and Dreamstime (ID 10514087 © Michael Schmeling and Dreamstime.com) websites, respectively.
The following acronyms are used for depositories: Head (Fig. 2) dark yellow, mouthparts pale. Two ocelli encircled by brown areas, close to compound eyes. All three visible palpal segments ( Fig. 2) setose, swollen antepenultimate segment dark brown, succeeding segments pale. 4 th segment slightly widening apically, 5 th segment apically tapering. Swollen palpal segment 1.6 times as long as broad medially from lateral view, and 1.1-1.3, 1.2 [1.1] times as long as height of compound eye. Ratios of three apical palpomeres 1.0: 0.9: 0.9. Antenna yellow with 2+13 segments. Scape and pedicel with brown setae, flagellum with somewhat paler setosity. Scape elongate cup-shaped, 1.7-2.2, 2.0 [2.2] times as long as wide apically. Pedicel cup-shaped, 0.9 times as long as wide apically. Flagellomeres rectangular, about twice as wide as long. Apical flagellomere conical, about 1.6 times as long as wide basally. Thorax yellow, mesonotum medially, laterotergite and mediotergite somewhat darker. Hind margin of laterotergite narrowly brown. Anterior part of mesepimeron with a dark brown patch leaving anteroapical margin yellow. Haltere with pale knob, and basally pale and apically yellow stem. All setosity on thorax brown. Scutum entirely covered with decumbent setae, scutellum with setae including two pairs of marginal bristles, laterals shorter than internals. Antepronotum with setae including 6-8  because of setae on both surfaces; other veins bare. Crossvein r-m apically disjunct. M1+2 3.5-3.7, 3.6 [3.7] times as long as r-m. M2 not reaching wing margin, broken 0.4-0.8, 0.6 [0.4] times of M1+2 length before it. Posterior fork begins clearly before anterior fork, at the middle of M1+2. Legs yellow, hind femora infuscated at apical fourth. Tarsi seem darker because of dense brown setae. Hind coxa with 4 [4] posterolateral bristles basally, with 0-2 [2] posterior bristles apically, and with ca. 30 weaker setae along posterolateral margin. Ratio of femur to tibia for fore-, mid-and hind legs: 1.5; 1.1; 1.0. Ratio tibia to first tarsomere for fore-, mid-and hind legs: 1.0; 1.2; 1.4. Fore-tibia with a spur about 0.5 of fore basitarsus; mid-tibia with anterior spur about 0.3-0.4, 0.4 [0.3] and with posterior spur about 0.6-0.7, 0.7 [0.6] of mid basitarsus; hind tibia with anterior spur about 0.5-0.6, 0.6 [0.5] and with posterior spur about 0.6-0.7, 0.7 [0.6] of hind basitarsus. Abdomen with first segment dorsally and laterally light brown and ventrally yellow. 2-4 segments dorsally brown with anterior and posterior margins yellowish, and laterally and ventrally yellowish; succeeding segments brownish. Terminalia (Figs 3-9) with gonocoxite basally yellow and apically brownish; gonostylus brownish; sternite 8 seems brownish because of dense setosity. Basal two thirds of sternite 8 cylindrical, apical third tapering, apex truncated. Basal third of sternite 8 membranous and bare, apical setae stronger than other setae. Gonocoxite slightly oblong, with broad ventral incision more than half of gonocoxite height. Ventral incision of gonocoxite with apically pointed basal projection about one third height of incision. Ventral medial margin of gonocoxite angular. Dorsal medial margin of gonocoxite simple. Cerci setose, clearly separated, basally wide, well tapering apically and protruding over gonocoxite. Basal half of gonocoxite bare, apical half with strong bristles. Dorsal branch of gonostylus rectangular, apically rounded, with a medially situated sclerotized comb of about half height of branch on its ventral surface. Apical setae somewhat stronger, deviating from other setosity of the branch. Dorsal branch of gonostylus with an indistinct basal tubercle on its ventral surface, close to base of medial branch. Ventral branch of gonostylus bare, subequal to dorsal branch, with serrated lateral margin and medially drawn out to a distinct lobe. The apical third of ventral branch is well tapering in ventral view. Medial branch of gonostylus divided at apical two thirds into two subequal lobes: ventral lobe rectangular, apically truncated, bearing 9-10 setae on its ventral part; dorsal lobe beak-shaped with two setae subapically on its ventral margin. Epiproct rounded with small setulae that arise in lines of 4 to 8 from small ridges. Hypoproct bowl-shaped with well-outlined lateral shoulders.

IAvH
Female. Unknown. Biology. Unknown. Etymology. The species is named to indicate its occurrence at high altitude (2730 m a.s.l.): Latin monticola means "mountain dweller". The specific epithet is noun in apposition.
Comments. The paratype has seemingly 14 flagellar segments at one side, caused by an aberrantly divided apical one. This, as well as partial fusion of some flagellar segments unilaterally, is common and frequently observed in the Palaearctic specimens of the genus (OK pers. obs.). According to the structure of male terminalia, especially in having the medial branch of the gonostylus divided into two subequal lobes, the species belongs to the C. murina species-group as defined by Kurina (2001). Within the group, C. monticola sp. n. shares a 13-segmented flagellum and brown to dark brown swollen antepenultimate palpal segment with two Palaearctic (viz. C. semiflava Staeger, 1840 and C. borealisa Wu in Wu & Zheng, 2000) and three Nearctic (C. manca Johannsen, 1912, C. scita Johannsen, 1912 andC. gracilis Fisher, 1938) species. Cordyla semiflava, C. borealisa and C. manca have the sternite VIII subapically remarkably constricted, while it is smoothly tapering in C. monticola sp. n. The shape of the lobes of medial branch of the gonostylus and the hypoproct are different from those in all species of the group.  Description. Male (Fig. 10). Total length 2.9-3.4, 3.2 [3.4] mm (n=5). Head (Fig. 11) dark yellow, mouthparts somewhat paler. Two ocelli encircled by brown areas, close to compound eyes. All three visible palpal segments (Fig. 11 (Figs 12-19) with basal part of gonocoxite and cerci yellow; apical part of gonocoxite slightly darker; dorsal branch of gonostylus yellow; ventral and medial branches of gonostylus brown. Sternite 8 oblong, apical fourth conical, apex truncated, basal half membranous and bare, setae on apical quarter somewhat stronger than other setae, two apical setae well deviating from other setosity. Gonocoxite subquadrate, with narrow ventral incision about half height of gonocoxite. Ventral medial margin of gonocoxite apically angular and with membranous formations dorsad from the ventral surface of gonocoxite. Dorsal medial margin of gonocoxite simple. Cerci setose, setae on medial margin slightly stronger, deviating from other setosity; clearly separated, prolonged, subapically somewhat constricted, not protruding over gonocoxite. Basal half of gonocoxite bare, apical half with strong bristles. Dorsal branch of gonostylus elongated, tapering, without sclerotized comb, dorsal surface with homogeneous setosity. Ventral branch of gonostylus bare, about half as long as dorsal branch, with serrated lateral margin. Apical corners of ventral branch of gonostylus drawn out to small lobes: ventral wider and rounded, dorsal narrow. Dorsal margin of ventral branch of gonostylus with wide and shallow incision. Medial branch of gonostylus divided into two lobes: 1) ventral lobe with three apical protrusions separated by concavities (ventral finger-like protrusion well discernible at internal view), internal surface with one strong and three weaker setae, and 2) dorsal lobe curved, tapering, as long as the medial protrusion of ventral lobe and with three medial setae. Epiproct apically rounded, covered with small setulae. Hypoproct indiscernible.

Biology. Unknown.
Etymology. The specific name is derived by the Greek prefix pseudo-from the Palaearctic species Cordyla pusilla Edwards, 1925 to indicate their morphological similarity.

Cordyla reducta
Female. Total length 2.5-3.4, 2.9 mm. Wing length 1.7-2.5, 2.1 mm. Ratio of length to width 2.4-2.7, 2.6. Antennae 2+9 segments. In setosity and coloration similar to male, except for entirely pale second abdominal segment. Both M1 and M2 not reaching wing margin, M4 extremely faint at its distal part (Fig. 26). Terminalia  (Figs 34-37) light brown. Cercus two-segmented: apical segment small, with a few long setae deviating from other setosity, obliquely connected with basal segment; basal segment long ovate, sinusoidal and wider than apical segment, ventroapical corner drawn out to a setose small lobe. Gonapophysis VIII membranous, visible in ventral view, apically rounded. Tergite VIII rectangular, subequal to length of basal segment of cercus, apically angular, basally and apically emarginated in dorsal view. Sternite VIII tapering lateroapically, with deep medial cleft in ventral view. Tergite VII about twice as long as tergite VIII, apically widening and with apical incision in dorsal view. Sternite VII apically conical, subequal to length of tergite VII. Tergite VI apically emarginated in dorsal view.
Biology. Unknown. Etymology. The specific name refers to the distally extremely reduced medial veins of the female wing: from Latin reducta meaning "distant". An adjective.
Comments. By the structure of male terminalia, C. reducta sp. n. belongs to the C. fusca species-group (cf. Kurina 2001). In its 12-segmented flagellum and yellow to light brown swollen antepenultimate segment of palpus, the new species is similar to the Palaearctic C. flaviceps (Staeger, 1840) and Oriental C. borneoensis Kurina, 2005.  The male terminalia of C. reducta sp. n. are remarkably different from these two species but otherwise resemble the Palaearctic C. fasciata Meigen, 1818 in having a similar outline to the ventral and dorsal branches of the gonostylus. However, the medial branch of the gonostylus is hump-backed and medially extended in C. reducta sp. n., while it has two small medial lobes in C. fasciata (cf. Zaitzev 2003: fig. 21-27). All studied female specimens have both medial veins of the wing distally extraordinary reduced (Fig. 26), unique among the species worldwide.

Discussion
Herein we present the occurrence of the genus Cordyla from the Colombian Andes (Fig. 38), representing the first described species in the Neotropical region. However, according to Vockeroth (2009: 276), unidentified specimens of Cordyla were previously known from Mexico, Belize, Guatemala, and Costa Rica. We were able to study the material housed at the Instituto Nacional de la Biodiversidad (INBio), San Jose, Costa Figure 38. Collecting localities of Cordyla species in Colombian Andes. 1 "Parque Nacional Natural Farralones de Cali" 2 "Santuario de Flora y Fauna Otún Quimbaya" 3 "Santuario de Flora y Fauna Iguaque". Rica, that includes eight females from the provinces of Guanacaste, San José, Heredia, Puntarenas, and Limón (Vockeroth 2009;SSO pers. obs.). Because of the absence of associated male specimens, the formal description of species from that material has not been performed at the moment.
The presence of Cordyla in the north-western part of Colombia, in the Neotropical region, clearly corresponds to a secondary extension of a Nearctic clade to the south. The range of this extension is, however, restricted to the mountains of Colombian Andes. In spite of having studied a vast fungus gnat material from the Amazonian basin, the genus has not been recorded there (SSO, OK pers. obs.). This distribution pattern is actually not restricted only to Cordyla within the Mycetophilidae. Also Docosia adusta Oliveira & Amorim, 2011 belongs to a group of Nearctic mycetophilid species reaching Colombia. According to regionalization of the Neotropical region by Morrone (2014), two of the three localities ("PNN Farralones de Cali" and "SFF Otún Quimbaya") lie in the Pacific Dominion and "SFF Iguaque" is located in the South American transition zone called Paramo province. Cordyla reducta sp. n. was recorded from all three localities while C. monticola sp. n. and C. pseudopusilla sp. n. are in the present stage of knowledge endemic to the Paramo province only (Fig. 38).
The complexity of the overlap of different biogeographical elements in Colombia was highlighted by Oliveira et al. (2007) and Oliveira and Amorim (2011). The Colombian fauna encompasses elements of Nearctic origin (p. ex. Docosia adusta), tropical origin, and a number of typical circum-antarctic elements that reach the north-western part of Neotropical region following the Andes final uplift to the north. The genera Paraleia Tonnoir, of which six new species were recently described from the Colombian Andes (Oliveira and Amorim 2012), and Procycloneura Edwards, of which at least ten species are being described by Oliveira and Amorim (in prep.) from Colombia and Costa Rica, are examples of amphinotic elements in Colombian fauna. Further studies of the diversity of Mycetophilidae and Cordyla in the Andes would contribute to a better understanding of the distributional patterns into the family and, hence, the biogeographical evolution of the region.