Austromerope brasiliensis, Machado, Renato Jose Pires, Kawada, Ricardo & Rafael, Jose Albertino, 2013

Machado, Renato Jose Pires, Kawada, Ricardo & Rafael, Jose Albertino, 2013, New continental record and new species of Austromerope (Mecoptera, Meropeidae) from Brazil, ZooKeys 269, pp. 51-65 : 54-61

Austromerope brasiliensis sp. n.

Type material.

Holotype, BRAZIL: Espírito Santo: Domingos Martins: Pico Eldorado, 20°22'27.19"S, 40°39'33.35"W, 05-12.vii.2003, Malaise trap, R. Kawada col. - 1 male (UFES). Condition is good, but with left antennae broken and apex of right hind leg missing.

Diagnosis.

This species is characterized by the semi-elliptical wings with many crossveins (Fig. 2b), the large genital forceps (Fig. 1), and by the truncate expansion of the apex of the basal segment of the forceps (Fig. 3d).

Description

(male holotype). Body length: 20 mm; wing length: 13.8 mm. Head: Eyes black, encircling antennae and almost touching each other dorsally (Fig. 4a); cuticle between and around eyes dark-brown (Fig. 4a). Ocelli absent. Frons, clypeus, labrum, and gena brown. Mandible dark-brown, palps pale (Fig. 4a). Antennae pale, scape broader than pedicel, which has the same width as basal flagellomeres in frontal view; 47 flagellomeres (each wider than long), the basal and apical ones thinner in lateral view (Fig. 3e). Head and body completely covered by small pale setae. Thorax: Pronotum brown, except for 2 black lines, 1 medial longitudinal, the other transverse, sub-apical (Fig. 4b); anterior border pale and folded dorsally. Pronotum as wide as head. Meso- and metanotum dark brown, both broader than pronotum, metanotum with anterolateral region serrated and modified into stridulatory organ (Fig. 4b). Thoracic pleura brown to dark brown. Legs: All pale and of same length (Fig. 2a). Tibia with 2 apical spurs. Tarsi 5 segmented. Pretarsal claws with small teeth (Fig. 3f). Wings: (Fig. 2) Semi-elliptical, membrane fuscous but hyaline around crossveins, slightly darker in inferior area of the wing. Membrane under first branch of M (until the 1st fork) hyaline in hind wing. Veins pale. Costal vein with many transverse rows of small, pale setae. Sc with many branches parallel to C. Rs and M divided into 11 and 9 branches respectively in the forewing, and 12 and 11 in the hind wing. Cu2 ending close to Cu1 in apical half of forewing. Cu2 bifurcated in hindwing. Jugal lobe modified into stridulatory organ in forewing. Abdomen: Segments I-IV slightly darker than others (Fig. 3a) and with sparse pillosity medially. Segments V-IX brown with denser pillosity medially (Fig. 4c) [glabrous in Merope tuber , Fig. 8c]. Tergite I longitudinaly divided medially. Tergite IX with posterior margin truncated and longer than tergite VIII (Fig. 3b). Terminalia: Anal dorsal plate curving down in lateral view, apex truncated with acute projection medially in dorsal view (Fig. 3b). Cercus small, rounded, with small pale setae (Fig. 3b). Genital forceps pale, long, slightly longer than abdomen (Fig. 1). Basal segments of forceps subparallel, with proximal region covered by long pale setae and with inner margin expanded (Fig. 3b); distal extremity with small truncate expansion on inner margin (Fig. 3d). Apical segment curved, with apex truncate (Fig. 3d). Basal segment broader and more than 2x longer than apical segment (Fig. 3c).

Etymology.

The specific epithet was named for the country where the specimen was collected.

Discussion.

Killington (1933) described the genus Austromerope from Australia and pointed out several characters that differentiated it from Merope , including: prothorax as wide as head (Figs 4b, 8a); pretarsal claws with small teeth (Fig. 3f); apical spine on the basal segment of the forceps (Fig. 5a); jugal lobe of forewing narrow and elongate (Fig. 5b); Rs with 5 or 6 bifurcations (Figs 2b, 5b); M with 2 bifurcations; the great number of crossveins; and costal crossveins parallel to C (Figs 2b, 5b). The new species described here shares all of these defining characters with Austromerope poultoni (except the apical spine on the basal segment of the forceps, which is just a truncated expansion in the Brazilian species). In addition, the new species and the Australian one have some other characters in common, such as: the color pattern of the wings and body; antennal flagellomeres wider than long (Fig. 3e); tergite IX longer than tergite VIII (Fig. 3b); the shape of the basal segment of the forceps (subparallel); and the size of the basal segment of the forceps, which is more than 2 × longer than the apical segment (Fig. 3c) (almost 1.5 longer in Merope tuber , Figs 7a, 8b). Because of all these shared characteristics we have decided to include the Brazilian species in the genus Austromerope and not in a new genus, despite the disjunct distribution.

Austromerope brasiliensis can be separated from Austromerope poultoni by Cu1 not connected with M in Austromerope brasiliensis (Fig. 2b), but connected with M by a short distance basally in Austromerope poultoni (Fig. 5b); by the truncated apical margin of abdominal tergite IX (Fig. 3b), which is rounded in Austromerope poultoni ( Killington 1933; Fig. 5); by the truncated apical expansion of the basal segment of the forceps (Fig. 3d), which has a strong apical spine in Austromerope poultoni (Fig. 5a); and by the truncated apex of the apical segment of the forceps (Fig. 3d), which is pointed in Austromerope poultoni (Fig. 5a).

Family distribution.

This is the first record of Meropeidae in the Neotropical region, and together with Bittacidae , it is one of the only two families of Mecoptera existing in Brazil ( Machado et al. 2009). The family’s disjunct distribution was discussed by Byers (1973), who compared it to the distribution of the other mecopteran families. He noted that the North American fauna seemed to be more closely related to the Eurasian fauna, with some families such as Boreidae , Panorpodidae , and Panorpidae , occurring only in these areas. He further commented that the Australian fauna, in turn, was basically endemic except for 1 family, Nannochoristidae , which also occurred in South America. Consequently, Byers (1973) suggested that South America was probably the connection between the North American species and the Australian one. Furthermore, he also wondered, in case his hypothesis was true, if there might be another Meropeidae species waiting to be discovered in South American forests. The discovery presented here therefore confirms Byers’ (1973) hypothesis, but likely for a different reason. The subsequent description of the fossil species Boreomerope antiqua Novokschonov, 1995 suggests that another distribution hypothesis needs to be considered.

Novokschonov (1995) discussed the relationships among the 3 Meropeidae genera, and highlighted the difficulty to decide which 2 are sister species. Furthermore, he mentioned different characteristics that can be used to approximate any genus, such as Cu1 connected to M for a short distance and Sc branching pattern of Sc, which are shared between Austromerope and Boreomerope ; the low number of Rs and M branches indicating a closer relationship between Merope and Boreomerope ; and the short length of Cu2, shared by Merope and Austromerope . The discovery of the new Austromerope species from Brazil helps rectify some of these inconsistencies indicated by Novokschonov (1995). The character used to join Merope and Austromerope , the short length of Cu2, is not useful since it is much longer in Austromerope brasiliensis than in any other species. The features suggesting a relationship between Austromerope and Boreomerope are also problematic; the connection between Cu1 and M does not occur in Austromerope brasiliensis , and the number, length, and shape of the Sc branches, actually appear more similar between Merope tuber and Boreomerope antiqua . On the other hand, the large number of branches of Rs and M in both species of Austromerope suggests that it is probably a constant feature within the genus, and consequently the low number in Merope and Boreomerope sug gests these 2 genera are closely related. Moreover, the small number of crossveins and the broad area between Sc and R1 may suggest a closer relationship between Merope and Boreomerope . If the hypothesis of Merope + Boreomerope is true, it is notable that the species from the same hemisphere are closely related to each other. Therefore, we deduce that after the breakup of Pangea the family was divided into 2 main branches, 1 in the southern hemisphere, represented now by Austromerope , and 1 in the northern hemisphere, currently represented by Merope tuber . Boreomerope antiqua is from the Middle Jurassic, a period when the continents had already split. It would therefore belong to the northern branch. The widespread distribution of Meropeidae corroborates the fact that the family arose when all continents were connected. In fact, the current global distribution of the mecopteran family Bittacidae ( Penny 2012) as well as the presence of some Mecoptera fossils from the Permiam period (290-248 MYA), also when all the continents were united ( Grimaldi and Engel 2005), further corroborate this hypothesis. The similarities between the 3 extant species of Meropeidae suggest that despite the early bifurcation and the current distribution of the family, the evolution of the group was very conservative, as mentioned by Byers (1973).

Conservation.

The most intensely studied and explored area for Mecoptera in Brazil is the Southeast region ( Machado et al. 2010), where Austromerope brasiliensis was collected. However, despite all previous collecting efforts in this area the species had never been recorded before. The specimen was collected in a private ranch near a forest fragment surrounded by farms in the Atlantic Forest biome, one of the most threatened in Brazil. The discovery of this new relict species is an important signal to reinforce the conservation of this biome. Certainly there are many more mecopterans species yet to be discovered in these forests.