﻿Taxonomic review of the Oriental genus Phylladothrips Priesner (Thysanoptera, Phlaeothripidae)

﻿Abstract Species of the Oriental subtropical and tropical genus Phylladothrips of fungus-feeding thrips exhibit some diagnostic character states, usually with abdominal tergite VIII bearing two pairs of wing-retaining setae and male tergite IX setae S2 about as long as S1. These species are quite small, and the maxillary stylets unusually broad for Phlaeothripinae. Phylladothripstrisetaesp. nov. from Xizang, China and P.selangorsp. nov. from Selangor, Malaysia are described, and P.fasciae is newly recorded from China. All 11 species in this genus are revised with an illustrated key.


Introduction
Species of the Asian mainly tropical genus Phylladothrips are small-sized fungus-feeding thrips that live on dead leaves and branches, or at the base of grasses.They share this habitat with several other fungus-feeding Phlaeothripinae, including species of Apelaunothrips and Stigmothrips (Okajima, 1988), as well as some in the genera Adraneothrips and Holothrips.The original author of the genus, Priesner (1933), considered that it was related to plant feeding thrips in the tribe Haplothripini, but all known species of Phylladothrips have abdominal tergite VIII with one or two pairs of wingretaining setae.This is a particularly unusual character state that is known only in the fungus-feeding species of three Phlaeothripinae genera Lizalothrips, Propesolomonthrips and Solomonthrips.These genera are recorded widely from northern Australia, Solomon Islands, the Philippines, Indonesia and Fiji.However, all members of these genera have the typical slender maxillary stylets (scarcely 3 μm wide) found in Phlaeothripinae.In contrast, the species of Phylladothrips have broader maxillary stylets (almost 5 μm wide), a character state shared only with species of Docessissophothrips genus-group and ZooKeys 1185: 241-253 (2023), DOI: 10.3897/zookeys.1185.113895 Lihong Dang et al.: The Oriental genus Phylladothrips Apelaunothrips amongst the Phlaeothripinae.These stylets are only slightly more slender than the stylets of some Idolothripinae species, that is, they are slightly less than 5 μm wide whereas in Idolothripinae they are always more than 5 μm.A further character state complication is that in males of subfamily Phlaeothripinae the tergite IX setae S2 are usually shorter and stouter than setae S1, whereas in males of Idolothripinae setae S1 and S2 are similar in size, such as Ophthalmothrips (Li et al. 2022).Males of Phylladothrips and Solomonthrips share the condition of S2 setae with Idolothripinae, although the only known male of Propesolomonthrips has the Phlaeothripinae condition.These genera emphasize the problems involved in the sub-family classification of Phlaeothripidae and suggest that Phlaeothripinae and Idolothripinae are not sister-groups.An alternative interpretation of the confused pattern of character states might be that Phylladothrips and Holothrips represent a reversal from hyphal feeding Phlaeothripinae ancestors to feeding on spores, possibly small, thin-walled conidia that breakdown when specimens are prepared for slide mounting.
Nine species are currently included in the genus Phylladothrips (Thrip-sWiki 2023), and in describing seven of these Okajima (1988) presented a generic diagnosis and key to all nine species.The only other published mentions of the genus are by Ananthakrishnan (1971), Reyes (1994) and Dang et al. (2014), but none of these involved extensive comments.Of the nine species, P. fasciae Okajima, P. gracilis Okajima and P. lateralis Okajima were described from Indonesia, P. pallidus Okajima known only from Taiwan, P. bispinosus (Okajima) only from the Philippines, and P. niger Okajima only from Malaysia.The type species, P. karnyi Priesner, was described from Java, Indonesia, and subsequently recorded from southern India (Ananthakrishnan 1971).Two species are recorded more widely, P. pictus Okajima from Japan, Taiwan and the Philippines, and P. similis Okajima from Thailand, Malaysia, Indonesia and the Philippines.Here we newly record P. fasciae from Xizang, China, and describe Phylladothrips trisetae sp.nov.from Xizang, and P. selangor sp.nov.from Malaysia, together with an illustrated key to all 11 known species in the genus.

Material and methods
The descriptions, photomicrograph images and drawings were produced from slide-mounted specimens with Nikon Eclipse 80i microscopes.Images were prepared with a Leica DM2500 using DIC illumination, and processed with Automontage and Adobe Photoshop v.7.0.The abbreviations used for the pronotal setae are as follows: am -anteromarginal, aa -anteroangular, ml -midlateral, epim -epimeral, pa -posteroangular.The unit of measurement in this study is the micrometre (μm).Most specimens studied here are available in the School of Bioscience and Engineering, Shaanxi University of Technology (SNUT), Hanzhong, China, the Australian National Insect Collection (ANIC), CSIRO, Canberra, Australia, and Tokyo University of Agriculture (TUA), Tokyo, Japan.Further slides were studied on loan from the Senckenberg Museum, Frankfurt (SMF).
Note.Most species of Phylladothrips are found in the tropic and subtropic regions of Asia (Fig. 1).However, although described from Taiwan, the distribution of P. pictus extends to the temperate region, where this species was recorded from the Ryukyu Islands, the Izu Islands and Honshu of Japan (Okajima 2006).Three species of Phylladothrips are found in the subtropics of southern China -Guangxi and southeast of Xizang, where the fauna shares many thrips taxa with Southeast Asian countries and Japan (Dang et al. 2014).The area between mainland China and Australia is species-rich for thrips, not only both fungal feeding and plant feeding species.At present it is impossible to detect any distribution patterns due to limited exploration.

Phylladothrips fasciae
Comments.This species, described originally from Sulawesi, Indonesia on dead leaves and branches, can be distinguished easily by abdominal tergite II yellow in contrast to the rest of the brown body.By comparing the types of P. fasciae, one female and male from Xizang are here identified as this species, representing the first record of this species from China.The male has some different characters, such as abdominal tergite III yellowish brown (Fig. 20), between clear yellow II and brown IV, fore and hind femora clear yellow, and S2 (75 μm) slightly longer than S1 (65 μm) on tergite IX (Fig. 22).
Comments.Described from Sulawesi, Indonesia on dead Arecaceae branches, this species is similar in body coloration with another Indonesian species, P. lateralis from Bali Island.Together they can be distinguished easily from other Phylladothrips species by the largely yellow body, especially yellow heads.However, P. gracilis has unusual pale antennal segments I-II in contrast to P. lateralis with I-II brown.

Phylladothrips karnyi Priesner
Phylladothrips karnyi Priesner, 1933: 80. Note.The type species of the genus was described from a single female taken at Java, Indonesia on leaves of Ammomum sp.This specimen was studied by Okajima (1988), who indicated that the species can be distinguished from P. niger from Malaysia only by the parallel cheeks of the head although they are very similar in body coloration and shape.The type specimen was not seen during the present studies.
Comments.Known only from two males taken at Gilimanuk, Bali, Indonesia on dead Arecaceae fronds, this species is similar to P. gracilis, with the differences between them discussed above.
Comments.Described from Tanah Rata, West Malaysia, on dead leaves and recorded from Luzon National Park, the Philippines, this is the second species after the type species with the body uniformly brown; the third is described here as a new species from Xizang.The cheeks of head are distinctly constricted towards the base (Fig. 6), distinguishing this from the type species, P. karnyi.
Comments.Described from Kenting National Park, Taiwan on dead leaves, this species is one of the two Phylladothrips species having postocellar setae elongate and expanded at apex (Fig. 2), while the other one is P. bispinosus from the Philippines.However, in P. pallidus there are two pairs of wing-retaining setae on tergite VIII (Fig. 4) but only one pair in P. bispinosus.
Comments.Described from Kenting National Park, Taiwan, on dead leaves and branches and recorded from subtropical and temperate Japan (the Ryukyu Islands, Izu Islands and Honshu) on dead twigs, some type-specimens of this species were collected with P. pallidus.They are closely similar to each other in the bicolored body, but they can be distinguished by the shape of the postocellar setae, as indicated in the key, also the different color patterns, with head (Fig. 8) and abdominal tergite I brown in P. pictus but yellow in P. pallidus.One female and two males from Guangxi, China are exactly the same as the holotype and paratype specimens on loan from SMF and TUA, and this is the first record of this species from China.Phylladothrips pictus is also similar to the new species from Malaysia, but the differences between them are discussed under the comments of this new species.Description.Holotype.Female macroptera.Body bicoloured.Head, thorax and tube brown (Figs 7,23), abdominal segment I-III clear yellow, IV-V yellow with brownish at lateral 1/3, VI-IX yellow, tube brown with extreme base pale.Antennal segments I-II light brown, III clear yellow, IV brown with yellow at basal half, V-VIII uniformly brown (Fig. 13); fore legs clear yellow except brown coxa, mid legs largely yellow, but coxa brown and basal half of femora light brown, hind legs uniformly yellow.Wings yellow with slightly shading.
Thorax.Pronotum smooth with weak sculpture close to posterior margin, notopleural sutures incomplete (Fig. 7); setae am minute, aa, ml, epim and pa setae developed, expanded at apex (Fig. 7), basantra present but weak; mesonotum with weak sculpture in front part, all setae minute; mesopresternum eroded medially, reduced to two lateral plates (Fig. 15); metanotum weakly reticulate, three pairs of tiny setae on anterior angles, a pair of median setae slightly larger, pointed at apex.Legs without fore tarsal tooth.Fore wings slender, weakly constricted medially, without duplicated cilia; three pairs of subbasal setae well developed, expanded at apex, S2 about as long as S3.
Abdomen.Pelta reticulate, tall hat-shaped; abdominal tergites II-VIII with two pairs of wing-retaining setae, posterior pair on tergite VIII slightly smaller than anterior pair (Fig. 23); S1-S2 on tergite IX expanded at apex, S1 slightly shorter than S2, S3 the longest, about as long as tube, pointed at apex, accessory setae between S1 and S2 elongate, slightly shorter than S1, pointed at apex (Fig. 23); tube about 0.6 times as long as head, anal setae shorter than tube; sternites II-VIII with a row of 8-15 slender setae.
Comments.This new species is one of the typical bicolored species in this genus, and is closely related to P. similis and P. pictus as indicated in the key.However, it can be distinguished by the brown prothorax, whereas the prothorax is yellow in P. similis and P. pictus, despite the various abdomen color patterns.
Comments.Described from Mindanao, the Philippines, on dead leaves, and recorded from Indonesia, Thailand and Western Malaysia, this species seems widespread around Southeast Aisa and has various body colorations.It is difficult to distinguish from P. pictus indicated in the original description, but they are different in the shape of the male aedeagus (Okajima 1988: figs 19-21).A paratype female of P. pictus on loan from SMF had abdominal segment II clear yellow, but III-IX brownish yellow and intermediate in colour between II and the brown tube.The color of abdominal segments of P. similis is II-III yellow, IV-V brown, VI-VIII brown to brownish yellow, IX and tube brown.However, a female from West Malaysia had the abdomen largely brown (Okajima 1988).Variation in coloration also exists in many fungus-feeding Phlaeothipinae, such as the related genera, Apelanouthrips and Holothrips.Sometimes the color helps to distinguish species, but sometimes there are gradual changes in different specimens of one species.Description.Holotype.Female macroptera.Body brown.All legs brown with tibiae yellow at extreme apices also all tarsi, fore and hind femora paler on apical 1/4.Antennal segments brown, with III-VI basal stems yellow (Fig. 11).Wings shaded with brown, body setae brown.
Thorax.Pronotum smooth with weakly sculpture close to posterior margin, notopleural suture incomplete (Fig. 9); am and aa minute, ml, epim and pa setae developed, expanded at apex (Fig. 9), basantra present but weak; mesonotum with weak sculpture on front part, all setae minute, mesopresternum eroded medially, reduced to two lateral plates; metanotum smooth medially, with weak longitudinal reticulation laterally, three pairs of tiny setae on anterior angles, a pair of median setae slightly larger, pointed at apex (Fig. 16).Legs without fore tarsal tooth.Fore wings slender, weakly constricted medially, without duplicated cilia, three pairs of subbasal setae well developed, blunt at apex, S3 the longest (Fig. 17).
Abdomen.Pelta weakly reticulate, tall hat-shaped (Fig. 16); abdominal tergites II-VIII with two pairs of wing-retaining setae (Figs 16,21); S1-S3 on tergite IX shorter than tube, S1 shorter than S2, blunt at apex, S3 the shortest, pointed at apex, accessory setae between S1 and S2 elongate, but shorter than S1 (Fig. 21); tube about 0.6 times as long as head, anal setae much shorter than tube.Etymology.This species name is composed of two Latin words, tri and setae, based on its pronotum with three pairs of well-developed setae expanded at apex.
Comments.This new species is similar to P. karnyi and P. niger in having the body uniformly brown, but it can easily be distinguished by having three pairs of well developed and expanded setae on the pronotum (Fig. 9).This condition also occurs in P. bispinosus, but it can be distinguished by the short and pointed postocellar setae (Fig. 9), in contrast to the long and expanded ones in P. bispinosus.

Figure 1 .
Figure 1.Distribution sites of Phylladothrips species -indicated by yellow circles.