A new genus of gall–dwelling thrips from Costa Rica (Thysanoptera: Phlaeothripidae: Phlaeothripinae)

Un género nuevo de tisanóptero morador de agallas en Costa Rica (Thysanoptera: Phlaeothripidae: Phlaeothripinae)

Gerardo A. Soto–Rodríguez¹*, Kenji Nishida² and Axel P. Retana–Salazar³

¹ Hypericum Pharma, S.A. San José, San Pedro, Costa Rica. Apartado 1237–2050. *cultivosyasesorias@yahoo.com

³ Programa Universitario de biología Aplicada (PUA), Centro de Investigación en Estructuras Microscópicas (CIEMIC), Universidad de Costa Rica 2060.

Recibido: 21 noviembre 2011.
Aceptado: 27 febrero 2012.

Abstract

A new genus and species of thrips, Fourbethrips fiorella, inhabiting stems, petioles and leaf vein galls of a Melastomataceae from Costa Rica is described. The galls are induced by an unidentified gall midge larva (Cecidomyiidae). This new thrips can be distinguished from other genus and species of Phlaeothripinae by the shape of the pelta, the position of maxillary stylets in the head, the reduced and acute anterior pair of postocular setae, the long and capitate posterior pair of postocular setae, the presence of a group of minute setae, and a pair of short ventral setae in the middle area of the abdominal sternites II–VII. The tergites II–VII have a pair of campaniform sensillae.

Key words: gall, Cecidomyiidae, Melastomataceae, Neotropics, new species, taxonomy.

Se describen una especie y un género nuevos de tisanóptero, Fourbethrips iorella, que habita en agallas en tallos, peciolos y venas de la hoja de una Melastomataceae de Costa Rica. Las agallas son inducidas por una especie no identificada de Cecidomyiidae. Este nuevo tisanóptero se puede diferenciar de otros géneros y especies de Phlaeothripinae por la forma de la pelta, la posición de los estiletes maxilares en la cabeza, la presencia de 2 pares de setas postoculares, 1 par reducido y de puntas agudas y 1 par posterior largo y capitado, la presencia de un grupo de setas pequeñas y 1 par de setas cortas en los esternitos abdominales II–VII. Los terguitos con un par de sensilas campaniformes.

Palabras clave: agalla, Cecidomyiidae, Melastomataceae, neotrópico, nueva especie, taxonomía.

Introduction

Thysanoptera comprise approximately 6 000 described species and are divided into 2 suborders, Tubulifera and Terebrantia (Mound and Marullo, 1996; Crespi et al., 1997). Tubulifera include about 3 500 species, which are classified in a single family, Phlaeothripidae. Of these species, 700 feed only on fungal spores and are placed in the subfamily Idolothripinae, with the remaining 2 800 comprising the biologically diverse subfamily Phlaeothripinae (Crespi et al., 2004). About 300 species of thrips in 57 genera are known to form galls (Mound, 1994). Most of them are in the subfamily Phlaeothripinae (Crespi et al., 1997). Other thrips are related to host plants like domicile–builders, opportunists and exploiters, including inquilines and kleptoparasites (Crespi et al., 2004). Some species opportunistically invade galls, e.g. Grypothrips Karny and Dactylothrips Bagnall. These species invade any space which provides refuge and food. Other thrips, e.g. species of Koptothrips Bagnall, are kleptoparasitic that invade galls and kill or displace original occupants (Crespi et al., 2004). Others co–inhabit with other thrips causing no harm to each other (inquilines) (Crespi et al., 2004). Common examples of such inquiline thrips are Mallothrips indicus Ramakrishna and Margabandhu in galls of Trioza jambolanae Crawford (Triozidae) on Syzygium (Mytrtaceae); Haplothrips atriplicis Priesner in galls of Asphondylia conglomerate Stefani (Cecidomyiidae); Dolichothrips inquilinus Ananthakrishnan in galls of a psyllid on Ziziphus sp. (Rhamnaceae); Liothrips interlocatus Karny in galls of Trichilogaster acacia–longifolia Froggatt (Psyllidae) on Acacia floribunda (Vent.) Willd. (Fabaceae) (Ananthakrishnan, 1984); and Advenathrips inquilinus described by Morris, Mound and Schwarz (2000) that is considered a true inquiline, entering another thrips domicile and raising its own offspring without undue disturbance to the host. Opportunistic species have been recorded from Australia in Acacia trees where they inhabit galls that have been abandoned by gall–inducers or phyllode domiciles created by thrips or lepidopteran larvae. There are large–sized opportunists (Domeothrips Crespi, Morris and Mound; and Grypothrips Karny and Warithrips Mound) and small to minute that are found in any crevice on Acacia (Brakothrips Crespi, Morris and Mound; Corroboreethrips Mound and Moritz; Dactylothrips Bagnall; Katothrips Mound and Rhopalothripoides Bagnall) (Mound and Morris, 2000; Crespi et al., 2004). One of the opportunists, Katothrips flindersi Crespi, Morris and Mound, lives in groups within abandoned, hollow, blister–shaped phyllode mines created by a weevil on Acacia acrademia (Crespi and Mound, 1997).

In this paper we describe a new genus and species of Tubuliferan thrips that inhabits galls induced by a Cecidomyiidae on stems, petioles and leaf veins.

Materials and methods

In February 2003, galls were collected by Paul E. Hanson in a Premontane Moist Forest in Monteverde region, at Estación Poco Sol of Bosque Eterno de los Niños/Children's Eternal Rainforest (10°20' N, 84°40' W, 700 to 800 m elevations), Alajuela, Costa Rica. The second author dissected the galls and photographed the galls and live thrips using a Nikon Coolpix 4500 digital camera. The digital images of mounted adult specimens were captured with an Olympus IX–51 microscope. The holotype is deposited in CIT–CIEMIC. Paratypes are deposited in CIT–CIEMIC, CNI– IBUNAM, INBio, SMF, BMNH and UNA.

Description

Fourbethrips Soto–Rodríguez and Retana–Salazar n. gen. Type species Fourbethrips fiorella Soto–Rodríguez and Retana–Salazar.

Macropterous or apterous Phlaeothripinae. Head longer than tube; with 2 pairs of postocular setae (PO), anterior pair reduced and acute and posterior pair long and capitate. Holoptic eyes. Cheeks parallel. Antennae 8–segmented, III and IV with 2 sense cones each one. Antennal segment II with sensorium in apical third. Antennal segment III longer than IV. Antennal segment VIII shorter than the remaining segments. Maxillary stylets about one–third of the head width apart without a maxillary bridge. Mouth cone short and rounded. Pronotum with 5 pairs of capitate major setae variable in length. Probasisternum well developed. Prosternal basantra absent. Mesonotum weakly reticulated. Metanotum reticulated with a pair of short setae in the middle. Sternopleural sutures complete. Fore femora enlarged and expanded with an apical tubercle in both sexes, femora more developed in females. Fore tibiae with tubercle at inner apex and fore tarsus with developed tarsal tooth in both sexes. Mid and hind tarsi with a small tooth. Pelta longer than wide, elongate, with reticulation pronounced in the basal part and a pair of campaniform sensilla. Forewing pale, duplicated cilia absent. Abdominal tergites II–VII with 3 pairs of sigmoid wing–retaining setae. Sternites II–VII with a group of minute setae in the middle and a pair of short and acute setae. Abdominal tergites II–VII with a pair of campaniform sensillae. Tergite IX setae B2 shorter than B1 and B3 in both sexes. All setae of tergite IX shorter than tube. Tube shorter than head.

Remarks. This new genus can be distinguished from other genera in Phlaeothripinae by the elongate pelta, the position of the maxillary stylets in the head, the abdominal sternites II–VII with minute setae or microtrichia, and the pair of short discal setae. Microtrichiae are also present ventrally on mesonotum and metanotum. The anterior pair of PO setae are reduced and acute and the posterior pair are long and capitate; the head is longer than tube; the mouth cone is short and rounded; and the fore tibiae have a developed tarsal tooth in both sexes. Abdominal tergites II–VII have sculptured reticles in anterior position. Similar reticles are present in Kladothrips nicolsoni McLeish, Chapman and Mound and K. rugosus Froggat (McLeish et al., 2006) and in Johansenthrips galligena Retana and Soto (Retana–Salazar and Soto–Rodríguez, 2008), however, in Kladothrips they are present only in abdominal segments II–III (McLeish et al., 2006). In Fourbethrips n.g. these structures are present in tergites II–VII.

When compared to the original descriptions of related genera (Table 1), there are clearly separating characters of Fourbethrips, among the most important ones: the oral cone size, the structure of sense cones on antennal segments, the distance between length and wide of segment III, as well as the shape of pelta. Other characters that can be considered are that Eupatithrips has not a basantra on presternum, it has a tubercle on the inner edge of the femur, a small tarsal tooth and a cheek setae on tubercles. Besides, Macrophthalmothrips has bright contrasting colors which are usually yellow to brown, while Sedulothrips presents the anterior margin of pronotum strongly concave; the highly developed oral cone extents to mesosternum, the sensory cones on antennal segments are short and stout otherwise to genera on this study. This genus shares many characters with Fourbethrips. The latter also presents a different biology than Eupatithrips, Sedulothrips and Macrophthalmothrips, which are found in dead branches where they feed on fungal hyphae (Mound and Marullo, 1996) while Fourbethrips is a guest of Cecidomyidae galls inhabiting galls within live tissue.

Generic diagnosis: macropterous or apterous Phlaeothripinae. Head longer than tube; 2 pairs of postocular setae (PO), anterior pair reduced and acute and posterior pair long and capitate. Antennae 8–segmented, III and IV with 2 sense cones each one. Maxillary stylets about one–third of the head width apart. Without maxillary bridge. Pelta elongate, longer than wide. Three pairs of sigmoid wing–retaining. A campaniform sensilla in the abdominal tergites II–VII. Sternites II–VII with a group of minute setae. Fore tibiae with developed tarsal tooth in both sexes.

Etymology. The prefix of the generic name is derived from the French word fourbe, meaning deceitful or misleading.

Fourbethripsfiorella Soto–Rodríguez and Retana–Salazar n. sp. (Figs. 1–6, 10)

Measurements of female holotype in µm: Total length 3 175; head length 430; PO setae anterior pair 40; PO setae posterior pair 95; antennal segments I 70, II 85, III 140, IV 115, V 110, VI 100, VII 95 and VIII 55. Pronotum setae length: anteromarginal setae 57,5; anteroangular setae 40; mid–lateral setae 110; posteroangular setae 90, epimeral setae 155. Fore femora basal width: 240. Tarsal tooth: 70. Abdominal tergite IX setae: B1 180, B2 55 and B3 130. Tergite X (tube) length 275, basal width 100, apical width 55.

Male: Apterous. Similar to female in coloration and structure but smaller than the female, collected with the holotype. Material deposited in CIT–CIEMIC.

Taxonomic summary

Holotype: Macropterous female. COSTA RICA: Alajuela, Monteverde region, Estación Poco Sol of Bosque Eterno de los Niños/Children's Eternal Rainforest (10°20'N, 84°40'W, 700 to 800 m elevations. 13.ii.2003 (Paul E. Hanson). Host plant: cecidomyiid gall on stems, petiole or leaf vein of an unidentified Melastomataceae. Paratypes: 21 females and 3 males, body length range 3175–3600 µm, same locality as holotype.

Etymology. The first author dedicates this species to Fiorella Jiménez Muñoz, for her invaluable support and love over many years.

Biology. The thrips were found inside galls (Figs. 7–10) induced by an unidentified cecidomyiid (the adult cecidomyiid has not been reared). The gall chamber occupied by the thrips did not contain the cedidomyiid larva or pupa. Instead most of the chamber contained eggs, young and mature larvae, and adult thrips (Figs. 9–10). The gall shape was ovoid to globose. Its size varied depending on the position, e.g. galls on stems were 20 to 30 mm long (n= 2), whereas galls in petioles were larger than those on leaf veins (8 mm long, n= 1). The gall chamber sized approximately 15 mm long and 1.5 mm wide in cylindrical form (n= 2). Although the feeding behavior was not observed, nymphs and adults most likely feed inside the chamber on the gall walls. Under captive conditions, inside a plastic bag, some of the adults exited and entered the gall via an exit hole (ca. 1 mm diameter) (Figs. 7–8). At the exit hole of the gall, an adult thrips abdomen was observed (n= 2) (Fig. 8). It is unknown whether this species is a kleptoparasite or is just occupying 'abandoned' galls of the Cecidomyiidae; however, it seems to be quite specific to the gall, because it has not been found in any other galls in the same habitat (K. Nishida, pers. observ.). The species of Melastomataceae appears to belong to the tribe Blakeeae. No plant sample was preserved or vouchered. Species diagnosis. Body brown; antennal segments I brown, II shaded brown and light brown at apex, III and IV pale yellow, V brown with basal yellow, VI brown with basal third yellow, VII and VIII brown. All femora brown. Tibiae pale yellow; tube dark brown. Head 1,5 times longer than tube. Pronotum with anteromarginal setae short and posteroangular, anteroangular, epimeral and midlateral setae long and capitate. Pelta longer than wide, elongate. Setae B1–B3 shorter than tube.

Acknowledgments

To Laurence Mound for providing some literature and Paul E. Hanson for collecting and sharing the galls. Also thanks to Alexander J. Arrieta for the pictures of the mounted specimens.

Literature cited

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