Two new species of Pergalumna (Acari, Oribatida, Galumnidae) from Costa Rica, including a key to all species of the genus from the Neotropical region

Abstract Two new species of oribatid mites of the genus Pergalumna (Oribatida, Galumnidae), P. elongatiporosa sp. n. and P. striatiprodorsum sp. n., are described from leaf litter of a secondary forest in Costa Rica. Pergalumna elongatiporosa sp. n. is most similar morphologically to P. horvathorum P. Balogh, 1997 and P. sura P. Balogh, 1997, however, it differs from both by the body size, body surface ornamentation and morphology of notogastral porose areas A1 and A3. Pergalumna striatiprodorsum sp. n. is most similar morphologically to P. hawaiiensis hawaiiensis (Jacot, 1934) and P. strigulata Mahunka, 1978, however, it differs from P. hawaiiensis by the length of interlamellar setae and surface ornamentation of the prodorsum; from P. strigulata by the surface of ornamentation of the notogaster, length of interlamellar setae and morphology of bothridial setae. An identification key to known species of Pergalumna from the Neotropical region is given.


Introduction
Pergalumna is a large genus that was proposed by Grandjean (1936) with Oribata nervosa Berlese, 1914 as type species. Currently, it comprises more than 130 species having a cosmopolitan distribution collectively (Subías 2004(Subías , updated 2014. The generic characters of the genus are summarized by Ermilov et al. (2013a), an identification key to some species has been presented by Balogh and Balogh (2002).
In the course of taxonomic identification of Costa Rican oribatid mites collected in 2013, we found two new species of the genus Pergalumna. The main goal of our paper is to describe these species. Earlier, only three species were known from Costa Rica (P. Balogh 1997;Schatz 2006Schatz , 2007Ermilov et al. 2014): P. horvathorum P. Balogh, 1997, P. silvatica Hammer, 1961 and P. sura P. Balogh, 1997. An identification key to known species of Pergalumna from the Neotropical region is given in the present work.
Holotypes and paratypes were mounted in lactic acid on temporary cavity slides for measurement and illustration. The body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the ventral plate. The notogastral width refers to the maximum width in dorsal aspect. Lengths of body setae were measured in lateral aspect. All body measurements are presented in micrometers. Formulae for leg setation are given in parentheses according to the sequence trochanter-femur-genutibia-tarsus (famulus included). Formulae for leg solenidia are given in square brackets according to the sequence genu-tibia-tarsus. General terminology used in this paper follows that of Grandjean (summarized by Norton and Behan-Pelletier 2009 Integument. Body color brown to black-brown. Body surface and pteromorphs with dense microgranules (their diameter up to 2). Pteromorphs with poorly visible wrinkles. Prodorsum. Rostrum broadly rounded. Rostral (ro, 24-28), lamellar (le, 49-53) and interlamellar (in, 69-77) setae setiform, barbed. Bothridial setae (ss, 90-102) setiform, densely ciliate unilaterally. Exobothridial setae absent. Lamellar and sublamellar lines distinct, parallel, curving backwards. Insertions of lamellar setae distanced from the lamellar lines. Porose areas Ad small, elongate oval (8-12 × 2-4), located lateroposteriorly to interlamellar setae.
Type deposition. The holotype is deposited in the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia; one paratype is deposited in the collection of the Tyumen State University Museum of Zoology, Tyumen, Russia; one paratype is deposited in the collection of the Centro de Investigación en Estructuras, Microscópicas (CIEMIC), Ciudad de la Investigación, Universidad de Costa Rica, San José, Costa Rica.
Integument. Body color brown to black-brown. Body surface, pteromorphs and subcapitular mentum with dense microgranules (their diameter up to 2). Surface of prodorsum with numerous longitudinal stria. Pteromorphs with poorly visible wrinkles.
Type deposition. The holotype is deposited in the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia; seven paratypes are deposited in the collection of the Tyumen State University Museum of Zoology, Tyumen, Russia; one paratype is deposited in the collection of the Centro de Investigación en Estructuras, Microscópicas (CIEMIC), Ciudad de la Investigación, Universidad de Costa Rica, San José, Costa Rica.
Etymology. This specific name "striatiprodorsum" refers to the striate prodorsum.
Remarks. In having the striate prodorsum, setiform bothridial setae, absence of anterior notogastral margin and presence of three pairs of oval porose areas (Aa oval, rounded, located close to lm), Pergalumna striatiprodorsum sp. n. is most similar to P. hawaiiensis hawaiiensis (Jacot, 1934) from the Pacific Islands and P. strigulata Mahunka, 1978 from Mauritius. However, it differs from P. hawaiiensis by the short interlamellar setae (versus medium size in P. hawaiiensis) and striate prodorsum (versus only anterior part of prodorsum with stria in P. hawaiiensis); from P. strigulata by the absence of stria on notogaster (versus notogaster striate in P. strigulata), short interlamellar setae (versus medium size in P. strigulata) and barbed bothridial setae (versus smooth in P. strigulata).
Among Neotropical species Pergalumna striatiprodorsum sp. n. is most similar morphologically to P. decorata Balogh & Mahunka, 1977. However, it differs from the latter by the absence of anterior notogastral margin (versus anterior margin present in P. decorata), barbed bothridial setae (versus smooth in P. decorata), absence of stria on notogaster (versus notogaster striate in P. decorata) and microgranulate body surface and pteromorphs (versus with larger foveoles in P. decorata).