Two new species of Archaeopodagrion (Odonata, Philogeniidae) from the western foothills of the Tropical Andes, with biological observations and distributional records

Abstract Two new species of the damselfly genus Archaeopodagrion, A. recurvatumsp. nov. and A. mayisp. nov., are described from the confluence of the Tropical Andes and the Tumbes-Chocó-Magdalena biodiversity hotspots. Adults differ from the other known species in the shape of female posterior lobe of pronotum and male structures of cerci and paraprocts; the larva differs from other Archaeopodagrion species in the caudal lamellae structure and in the mandibular formula. The two new species are diagnosed, a morphological key to all known males and females in the genus is provided, and geographical distributions are updated. Finally, observations on habitat preferences for each newly described species are provided.


Introduction
Archaeopodagrion is a genus of Neotropical damselflies endemic to the rainforests of the Tropical Andes and the Tumbes-Chocó-Magdalena biodiversity hotspots. This genus has been poorly known; for a long time only the type species A. bicorne Kennedy, 1939 and the elusive A. bilobatum Kennedy, 1946 were reported from Ecuador, but in the last decade two more species were described: A. armatum Tennessen & Johnson, 2010 from southern Ecuador, and A. fernandoi Bota-Sierra, 2017 from Colombia, extending the distributional range of the genus almost 700 km north along the Andes.
Here, two new species of Archaeopodagrion from localities in Colombia and Ecuador are presented, extending the distribution of the genus further north within the western Andean foothills. Morphological descriptions accompanied with photographs of the diagnostic traits for both species are provided. Additionally, two updated keys for the adults of the known species of Archaeopodagrion, one for males (6 spp.) and another one for females (4 spp.) are presented. For A. recurvatum sp. nov. the morphological description of the penultimate instar larva is also provided. Besides the morphological descriptions, biological notes, a new distribution map, and some taxonomic remarks are offered, thus adding to the known diversity of this rare genus.

Materials and methods
Male and female adults and a female larva were collected for A. recurvatum but only male adults were collected for A. mayi. The F-1 (penultimate instar) larva was preserved in 80% ethanol, the adults were steeped in 96% ethanol for twelve hours and then dried. Specimens are deposited in the ANDES Entomology Museum, Universidad de Los Andes, and the CEUA Entomology Museum, Universidad de Antioquia.
Photographs of morphological structures were taken with a Nikon DS-U3 camera mounted on a Nikon SMZ25 stereomicroscope, and processed with the program NIS elements AR version 4.5. Descriptions were made by examining specimens under a Zeiss Stemi SV6 stereomicroscope, and measurements (in mm) taken with an ocular micrometer and a ruler. Wing nomenclature follows Riek and Kukalová-Peck (1984). Mandible nomenclature follows Watson (1956); labium nomenclature follows Corbet (1953). Wing measurements follow Bechly (1996) and head measurements follow Tennessen (2017). Abbreviations are as follows:

AL
Abdomen length: maximum length of the abdomen, measured from the first (S1) to the 10 th abdominal segment (S10) and including the caudal appendages ( Cercus length: maximum width of the cercus, measured from the insertion in S10 to the furthest point of the cercus tip in dorsal view; S1-10 Abdominal segments; TL Total length: maximum length of the specimen, measured from the furthest edge of the labrum to the 10 th abdominal segment (S10) including the caudal appendages (cerci and paraprocts), in dorsal view;

PpL
Paraproct length: maximum length of the paraprocts, measured from the insertion in S10 to the furthest point of the paraproct tip in dorsal view;

EpL
Epiproct length: maximum length of the epiproct, measured from the insertion in S10 to the furthest point of the epiproct tip in dorsal view. Diagnosis. Archaeopodagrion recurvatum lacks the tubercle bearing a hair pencil on the midlength of each paraproct and also lacks a well-developed internal tooth on the cercus, a character present only in A. bilobatum and A. bicorne. Among the females, A. recurvatum differs from the other three females described (females of A. bilobatum and A. mayi are unknown) by the unique shape of the posterior lobe of the pronotum (Fig. 3B, C). The larvae of A. recurvatum lacks the fleshy tubercles or spiniform setae present in the caudal lamellae of A. fernandoi; also A. recurvatum has a slenderer body than A. fernandoi and a different mandibular formula, since the molar crest in the left mandible of A. recurvatum possesses twice as many teeth as in A. fernandoi. The adults of A. recurvatum are also the smallest of the genus (male total length 35.0-38.0 mm, female 34.0 mm), with the average length in the genus ranging from 37.5 m for males and 36.5 mm for females in the smaller known specimens of A. armatum, to 45.0 mm for males and 42.0 mm for females in A. fernandoi (Kennedy 1946;Tennessen and Johnson 2010;Bota-Sierra 2017).

ANDES-E
Description. Male holotype. Small-sized damselfly, thorax brown with pale yellow stripes, abdomen brown with pale yellow spots, cerci in dorsal view conspicuously recurved, paraproct tips upturned, with tips contacting distal margin of cerci ( Fig. 1A eyes in life dark gray, with black borders; labium grayish brown, dark brown medially, with long pale setae; labrum and anteclypeus yellow, postclypeus brown, frons grayish brown; vertex, occiput and rear of head black, anterior and postero-dorsal surface of vertex and occiput with sculptured surface that refracts light producing green to red metallic colors; some scattered, dark brown setae on dorsum of head; occiput straight, dark brown with long, brown setae along entire width; antennae dark brown except base, basal half of first antennomere pale yellow ( Fig. 2A). Thorax: prothorax light brown. Anterior lobe strongly convex in lateral view, middle and posterior lobes with a deep medial depression, pronotal lobe prolonged laterally into trapezoid processes with a conspicuous spine directed toward mesinfraepisternum (Fig. 2B, C). Middorsal carina of pterothorax brown, mesepisternum brown with a yellowish wide stripe reaching humeral suture. Mesinfraepisternum and mesepimeron brown, metepisternum yellowish along the anterior half, becoming light brown near wing base; metinfraepisternum brown near metepisternum, the posterior half yellowish. Metepimeron yellow, with a slight brown stripe below metathoracic suture. Venter of thorax and coxae yellowish, femora, tibia and claws tan brown. Leg spines 2-4 times longer than spaces between bases of adjacent spines, these spaces increasing distally. Wings hyaline; Px 16-17 in FW, 15-16 in HW; Pt surmounting two to two and a half cells, dark brown with very narrow pale edges next to enclosing veins (Fig. 1A). Abdomen: S1-2 completely light brown; S3-7 light brown dorsally with narrow basal pale-yellow mark connecting to yellow lateral mark and then forming a yellow triangular mark reaching ventral side in S7-8. S9-10 dark brown dorsally, slightly yellow ventrally, S10 with a conspicuous central cleft ( Fig. 2A). Genital ligula with two lateroapical recurved flagella as in other species described for the genus (Fig. 2D). Cerci light brown, strongly recurved medio anteriorly with tips touching, giving a heart-shaped appearance, armed with some small denticles along inner margins; paraprocts in lateral view slightly longer than cerci but with divergent acuminate apex strongly recurved dorsally and armed with a small, blunt tooth at the tip ( Fig. 3A-D).
Female paratype. Measurements: TL 34; AL 26.8; FWL 22; HWL 21.1; WHW 7.1; FW PtL 1.1; HW PtL 1.2; HWd 5.1; HFL 4. Head: black except: labium pale yellow; labrum mandible base, genae and anteclypeus yellowish blue; postclypeus greyish brown with two yellow spots; antefrons greyish brown, postfrons brown, both with sculptured surface which extends to foramen except for lustrous space between antennae base and eyes, two yellowish blue elongated spots between antenna base and each lateral ocellus; antennae dark brown, base and basal half of first antennomere pale yellow; postocular lobe slightly protruding posteriorly beyond level of hind margin of compound eye, paraorbital carina distinct (Fig. 4A). Thorax: brown with antehumeral and metepisternal yellowish blue stripe, metepimeron pale yellow with a slight brown stripe below metathoracic suture (Fig. 1B, C). Posterior lobe of pronotum convex laterally with a small, angled projection (Fig. 4B, C). Metathoracic legs missing, coxae yellowish blue, femora dark brown externally and yellowish blue internally, tibiae and tarsi brown, armature brown. Eight spurs on the external side of right mesofemur and seven on left mesofemur, each as long as space between them or shorter, gradually increasing in size toward the apex. Eight spurs on the anterior side of right mesotibia and seven on left mesotibia, longer than the spaces between them and gradually decreasing in size toward apex. Tarsal claws with a supplementary tooth. Wings smoky. Pt dark brown surmounting two to two and a half cells, Px 18 in FW and 16 in HW. Abdomen: dark brown except light brown sides of S1-2, apical incomplete rings from S3 to S7 connected to ventrolateral stripes, and S8 ventrolateral stripe. Genital valves brown, internal edges of gv1 and gv2 serrulated, gv3 and gv4 with a large triangular process over the base of long and slender black styli (Fig. 4D).
Distribution. Known only from the holotype and paratype localities on the western slope foothills of the West Andean Cordillera at the Colombian departments of Risaralda and Valle del Cauca (Fig. 7).
Etymology. Named recurvatum (from the Latin recurvatum: curved inwards, with tips that are directed back to the point of origin) due to the peculiar structure of the male's cerci. Diagnosis. The males of Archaeopodagrion mayi are medium-sized, with total length ranging from 40.0 to 43.0 mm. They present a tubercle bearing a hair pencil on the midlength of each paraproct, a character shared with the males of A. armatum and A. fernandoi, and lack a well-developed internal tooth on cercus, a character shared only with A. recurvatum.
Description. Male holotype. Medium-sized damselfly, thorax brown with greenish yellow stripes, abdomen dark brown dorsally and light brown ventrally, with greenish yellow pale spots (Fig. 8). Abdominal appendages with characteristic morphology, comprising cylindrical cerci with tips directed posteroventrally, longer than paraprocts, and paraprocts with tips acute and directed dorsally (Fig. 10A-D base, genae, and anteclypeus pale greenish yellow; labium and labrum with long, pale setae; postclypeus greyish yellow, antefrons and postfrons dark brown, both with sculptured surface except lustrous space between antennae base and eyes and extending to occipital foramen; antennae dark-brown except pale yellow base, postocular lobe slightly protruding posteriorly beyond level of hind margin of compound eye, paraorbital carina distinct (Fig. 9A). Thorax: prothorax bright yellow with brown spots, pterothorax brown with antehumeral and metepisternal yellow stripe, metepimeron brown with a yellow stripe below metathoracic suture (Figs 8B, 9B). Anterior lobe of the prothorax subquadrangular, middle lobes arcuate medially (Fig. 10A), the posterior lobe of pronotum convex, prolonged laterally into two pairs of processes: one on superior margin and the other on inferior margin; superior pro- cesses long, curved dorsoposteriorly, their tips blunt and extending over a third of the pterothorax; inferior processes shorter, less than half the length of superior processes, and extending posteroventrally (Fig. 10B). Venter of thorax and coxae yellow, femora dark brown externally and pale brown internally, tibiae, tarsi and armature brown. Leg spines 2-3 times longer than spaces between bases of adjacent spines, interval between spurs subequal along all legs. Tarsal claws with supplementary tooth. Wings hyaline. Pt dark brown surmounting two to two and a half cells, ratio between distal and proximal length approximately 1:1. Px 18 in FW and 16 in HW. Abdomen: dark brown, S1 and S2 with yellow lateral stripes, S3-7 dark brown dorsally with narrow basal yellow ring connecting laterally to yellow stripe along ventral side in S7 and S8. S9 and S10 dark brown (Fig. 8). Cercus cylindrical, covered with denticles and scattered short setae, in lateral view longer than paraproct (Fig. 10C, D); paraprocts in lateral view with a strong ventral tubercle located at midlength, the tubercle bearing a conspicuous hair pencil apically, tips of paraprocts recurved, acute, hook shaped (Fig. 10D). Genital ligula with two lateroapical recurved flagella as in the other species described for the genus.
Distribution. Known only from the holotype and paratype locality in the western foothills of the Ecuadorian Andes in Imbabura Province (Fig. 7). Etymology. Named mayi, an adjective in the genitive case, after Dr. Michael L. May for his great contributions on the study of odonates, whose work ranges from basic taxonomy and systematics to complex ecological and physiological questions related to migratory patterns and to the body temperature regulation of dragonflies. Dr. May has established the foundation for many research topics in Odonatology and has supported the development of several odonatologists and their research.

Biological observations
The specimens of A. recurvatum were collected at two different locations with similar characteristics along the Colombian Western Andean foothills, where the climate is tropical, with temperatures ranging from 22 °C to 27 °C, high precipitation (> 3000 mm per year [Pravettoni 2019]) and tropical rainforest as the predominant vegetation. They were found on small to medium-sized fast flowing streams, with sand and gravel substrates surrounded by a mix of boulders and exposed bedrocks, interspersed with waterfalls, pools and rapids, within primary and undisturbed forests. The waters were clear, clean, and highly oxygenated. Archaeopodagrion recurvatum coexisted there with damselflies of other families such as Heteragrionidae, Polythoridae, and Platystictidae. Those streams are highly dependent on precipitation: during the wet season, the stream water level can increase 0.50 to 1.0 m, decreasing in the same proportion during the dry season. When the waters recede, apparently there are more available spaces for adults to emerge, using semi-submerged large stones and sticks as attachment substrate. Amaya-Vallejo (2009) identified odonate assemblages associated with different habitats within the Anchicayá zone, thus classifying most of the species inhabiting the previously described streams as stenoecious, or able to live only in a restricted range of habitats.
Archaeopodagrion mayi was collected at Los Cedros Natural Reserve in Ecuador. This reserve is located in the southernmost area of the Cordillera de la Plata, lying on the western side of the Andes mountains. The temperature generally fluctuates between 16-25 °C and the humidity can be as high as 100% due to the high level of precipitation (> 3000 mm per year [Pravettoni 2019]). The dominant type of vegetation is tropical rainforest. The specimens were found in a swampy trail left by a stream located inside a small canyon; the walls were covered with long roots and lianas. Both males were perching at the end of these roots, with their wings open as in individuals of Heteragrion and somewhat resembling females of this genus. The collection trip occurred right after the dry season and the climatic conditions were similar to the ones in the Colombian locations. The stream water level may have been reduced and A. mayi may have the same emergence habits as A. recurvatum. Polythoridae and Heteragrionidae were collected at the same place and considering the characteristics of the habitat and the classification made by Amaya-Vallejo (2009), A. mayi may also be a stenoecious species thus sharing similar habitat requirements with A. recurvatum. Despite the habitat requirements for both species, due to lack of surveys we suggest these to be data deficient category for the IUCN red species list.

Taxonomic remarks
The phylogenetic position of Archaeopodagrion was expected to be close to the Malagasy genus Tatocnemis based on morphological characteristics (Rácenis 1959). Dijkstra et al. (2014) proposed the family Philogeniidae for Archaeopodagrion and Philogenia genera based on molecular evidence only, but morphologically, the only character shared by them is the coiled flagella on genital ligula, with no further evidence of other reliable diagnostic characters (Bota-Sierra 2017). With the description of the larva of Archaeopodagrion (Novelo-Gutiérrez et al. 2020), some important taxonomic information supported Philogeniidae as a monophyletic group including the shape of the antennae and the caudal lamellae, the structure of the galeolacinia of the maxilla, the maxillary palp and the distointernal margins of tibiae and the prementum. Autapomorphic characters separating larvae of Archaeopodagrion from those of Philogenia become less apparent with the description of A. recurvatum because the caudal lamellae with basal, spiny, fleshy tubercles present in A. fernandoi are lacking in A. recurvatum. We propose that the mandibular formula is the most reliable character for separating larvae of Archaeopodagrion and Philogenia, following Novelo-Gutiérrez et al. (2020): the molar lobe in the right mandible of Archaeopodagrion does not present m denticles but it does in Philogenia, the molar lobe in the left mandible of Archaeopodagrion has only two m denticles but the number varies in Philogenia, and the tooth d in the left mandible of Archaeopodagrion is small, bluntly-pointed and close to tooth b whereas in Philogenia the shape is different and its position is quite variable.
Updated key for the adults of Archaeopodagrion (modified from Bota-Sierra 2017)

Key to males
1 Paraprocts with a tubercle bearing a hair pencil (Fig. 10D)