Research Article |
Corresponding author: Jerry L. Cook ( jcook@shsu.edu ) Academic editor: Laurence Livermore
© 2020 Jerry L. Cook, Robert W. Sites, Akekawat Vitheepradit.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Cook JL, Sites RW, Vitheepradit A (2020) The Pleidae (Hemiptera, Heteroptera) of Thailand, with the descriptions of two new species and a discussion of species from Southeast Asia. ZooKeys 973: 35-68. https://doi.org/10.3897/zookeys.973.54026
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The family Pleidae is represented in Thailand by four species in the genus Paraplea. Two of these species, P. frontalis and P. liturata, are widespread and relatively common in Southeast Asia. Two other species, P. lateromaculata Cook, sp. nov. and P. melanodera Cook, sp. nov., are described and only known from Thailand. Full descriptions are provided for all four species. The distributions of these species are discussed, with an emphasis on Thailand. Paraplea frontalis, P. liturata, and P. lateromaculata Cook, sp. nov. are relatively widespread within Thailand and have overlapping distributions whereas P. melanodera Cook, sp. nov. appears restricted to small brackish ponds near western coastal areas of peninsular Thailand.
distribution, Paraplea, taxonomy
The family Pleidae in Southeast Asia is represented only by species in the genus Paraplea. Paraplea areolata Paiva, 1918 was described from Myanmar (Burma,) and P. davaoensis Miyamota, 1981 and Paraplea sobrina (Stål, 1860) are known from the Philippines. Two species, P. frontalis (Fieber, 1844) and P. liturata (Fieber, 1844) are likely widespread in Southeast Asia, and also occur outside this region. In Southeast Asia, P. frontalis and P. liturata have been recorded from Indonesia, Myanmar (Burma), West Malaysia, Singapore, Taiwan, and Thailand. Paraplea frontalis is also known from China, India, Sri Lanka, and Taiwan, and P. liturata from Australia, Japan, and New Caledonia. Paraplea vittifrons (Horváth, 1919) is known from the type specimen from the Aru Islands of Indonesia, which is in maritime Southeast Asia.
Members of the family Pleidae are rarely collected. These are very small aquatic bugs that are often overlooked in nature and collections, and they occur in habitats that are rarely sampled. The most common habitat where pleids occur is in slow moving or stagnant waters, with rich vegetation (
The taxonomy of species in Pleidae is based primarily on a few key characters of uncertain taxonomic importance. Traditionally, genera could be identified solely on the index of their tarsal segments (
The genus Paraplea is the most widespread genus in Pleidae with 19 valid species. Two species are from the New World, known primarily from the Caribbean and the southeastern United States; four species are from Africa; two from India; two from Australia; three from Japan or Taiwan; and six from Southeast Asia. With the addition of the two species from Thailand described in this study, this region is clearly the most diverse for Paraplea. However, there are likely many more species that remain unknown and await discovery and description.
Most specimens for this study were field collected by co-authors Sites and Vitheepradit and their colleagues. Photographs of these collection sites, identified as L-numbers, are available in a Locality Image Database via a link from the internet site of the Enns Entomology Museum, University of Missouri. Other specimens were from previously collected materials deposited in the Snow Entomology Collection, University of Kansas (
BSI Body Shape Index (body width/body length) x 100
OI Ocular Index (narrowest width between eyes/width of head across the eyes) x 100; width between eyes is taken anteriorly in dorsal view, width of head is at widest point including eyes
PI Pronotal Index (length of pronotum/width of pronotum) x 100
SI Scutellar Index (scutellum width/scutellum length) x 100
Description of the ovipositor (gonapophyses) follows the terminology of
Four species were found in Thailand, two previously described and two new. Although the two previously described species, P. frontalis and P. liturata, are relatively well known, they lack a complete modern description. Both were partially redescribed by
= Ploa frontalis Fieber, 1844: Entomol. Monogr. p. 18.
= Plea frontalis: (Kirkaldy, 1898): Wien. Entomol. Zeit. 17: 141.
= Plea pelopea Distant, 1911: Fauna Brit. India 5: 336–337 (synonymized by
= Plea quinquemaculata Lundblad, 1933: Arch Hydrobiol. 12: 135–138 (synonymized by
Plea (Paraplea) frontalis:
Paraplea frontalis: Drake and Maldonado-Capriles 1956 (elevation to genus) 51: 53.
Paraplea frontalis was described as Ploa frontalis by
No holotype is designated.
All measurements are given in millimeters from 456 adult specimens from throughout Thailand as reported in the distribution portion of this paper. Specimens used for this description are deposited at
Body size. Total length, 1.89–2.32 (average 2.07) in Thailand specimens.
Color. Color may vary among individuals (Fig.
Head. Head (Fig.
Pronotum. Base color ranging from cream to light brown, honeycombing apparent in some specimens; most have visible central lighter colored vertical band without punctures (Fig.
Wings. Complete to posterior; punctures generally in irregular rows (0.02 in diameter) (Fig.
Legs. Typical leg measurements: prothoracic leg coxa 0.07, trochanter 0.11, femur 0.45, tibia 0.34, first tarsomere 0.02, second tarsomere 0.16,pretarsal claw 0.10; mesothoracic leg coxa 0.04, trochanter 0.18, femur 0.39, tibia 0.25, first tarsomere 0.02, second tarsomere 0.16, pretarsal claw 0.08; metathoracic leg coxa 0.04, trochanter 0.17, femur 0.47, tibia 0.53, first tarsomere 0.04, second tarsomere 0.18, third tarsomere 0.19, pretarsal claw 0.13 (see
Median ventral keel. Thoracic portions distinct from each other; prosternal keel rounded with posterior blunt tooth; mesothoracic keel almost rectangular; metathoracic keel irregularly shaped, somewhat in lobes, including posterior projecting small tooth, closely associated with abdominal keel, appearing almost fused; thoracic segments relatively similar between specimens. Abdominal keel variable, usually partially fused between segments, usually with four distinct teeth corresponding with first four abdominal segments. Figure of typical Thailand specimen in Fig.
Characters of female. Ovipositor roughly triangular in shape, 0.25 in length, with wide side apically (gonapophysis 1) at end of rectangular shaft (gonapophysis 2) (Fig.
Characters of male. Aedeagus bulbous and somewhat asymmetrical in the typical fashion of the family; operculum (subgenital plate) generally triangular, slightly wider than long (Fig.
Paraplea frontalis is a relatively widespread species in Thailand (Fig.
Hong Kong: New Territories, Yuen Long, 23 II 1971, P. & P. Spangler (5 specimens USNM). India: Pondicherry, Maindeon, 1901 (4 specimens USNM); India, Tanquebor (South India) 1951, P. S. Nathan (1 specimen USNM); Karikal, VII 1956, P. S. Nathan (5 specimens USNM). Laos: Vientaine, along Mekong River, 17°58'02.6"N, 102°36'17.6"E, 6 VIII 1997 Wolfgang G. Ulrich (1 specimens USNM). Malaysia: Penang, University of Sains Malay, 29 I 1983, H. C. Chapman (15 specimens USNM). Myanmar: Rangoon Burma (= Yangon, Myanmar) Kemmencline 10 I 1927 (2 specimens USNM); Rangoon Burma (= Yangon, Myanmar) Kemmencline 29 I 1927 (4 specimens USNM). Singapore: 1 IX 1955. Marshall Laird (8 specimens
Because of the wide geographic distribution and variable characters, it is possible that what has previously been considered to be P. frontalis may include more than one species. Previously, it has not been possible to differentiate between species variation and species boundaries. However, after viewing hundreds of specimens, it appears that there are some reliable characters as long as there is a series of specimens in the sample to account for the variation.
All measurements are in millimeters and were taken from 224 adult specimens from throughout Thailand as reported in the distribution portion of this paper. Specimens used for this description are deposited at
Body size. Total length, 1.21–1.58 (average 1.42) (Fig.
Paraplea lateromaculata sp. nov. specimens from Thailand. A mele in lateral view with typical coloration. B dorsal view of a light colored morph that shows dark banding and honeycombing. C frontal view of specimen in B. D female showing an alternatively colored form in lateral view without dark bands.
Color. Color may vary slightly among individuals (Fig.
Head. Head (Fig.
Pronotum. Base color usually light-tan but ranging between nearly white to brown, usually with lighter colored honeycombing apparent; most specimens have three distinct dark spots, one near posterolateral edge and one near the central posterior margin of pronotum (Fig.
Wings. Complete to posterior; punctures evenly dispersed with only small distance between punctures, not in rows (0.02 – 0.03 in diameter) (Fig.
Legs. Shape of legs as in Fig.
Median ventral keel. Thoracic portions distinct from each other, prosternal keel somewhat rectangular with small teeth at anterior and posterior edges; mesosternal keel small but distinctly squared in profile, slightly serrated; metathoracic keel segment somewhat rounded with prominent teeth. Abdominal keel on segments I-IV with distinct teeth, segment I appears fused to metathoracic keel. Figure of typical specimen in Fig.
Characters of female. Ovipositor roughly rectangular but apical side slightly wider (gonapophysis 1) at end of fused rectangular shaft (gonapophysis 2) (Fig.
Characters of male. Aedeagus bulbous and somewhat asymmetrical in typical fashion of family; operculum (subgenital plate) generally triangular, slightly longer than wide (Fig.
Paraplea lateromaculata is found throughout most of peninsular Thailand, and few specimens have also been collected in eastern Thailand (Fig.
Holotype
female, Thailand: Krabi Province, Amphur Nuea Khlong, Tumbon Klong Kanarn, Ban Klong Kanarn, pond 8°01.045'N, 99°00.450'E, 37 m, 8 I 2006, Vitheepradit and Prommi, L-903 (UMC). Paratypes (38 TOTAL): Singapore: Federated Malay States, 31 X 1955, Marshall Laird (1 paratype
Thailand: Chumphon Province: Amphur Lamae, Ban Suan Som Boon, 09°43.311'N, 99°06.208'E, 13 m, 20 VI 2006, Vitheepradit and Prommi, L-964 (7 specimens UMC); Amphur Sa Wi, Ban Kron, 10°17.390'N, 99°05.464'E, 5 m, 30 V 2004, Vitheepradit and Prommi L-728 (2 specimens UMC); Amphur Sa Wi, Ban Kron, pond, 10°14.542'N, 99°05.555'E, 6 m, 30 V 2004, Vitheepradit and Prommi, L-729 (5 specimens UMC, 1 specimen
The specific epithet combines two Latin roots, latero- meaning the side and –macula meaning spot. Thus, the name refers the distinct dark spot on the lateral side of the hemelytra. This spot is similar to the dorsal pronotal spots found in this species and P. liturata.
In general appearance, P. lateromaculata sp. nov. could be misidentified as P. liturata that is missing two of its dark pronotal spots. However, several consistent characters separate these species. The most obvious of these characters is that P. lateromaculata sp. nov. has one dark spot on each side of the hemelytra, anteriorly near the costal margin, which is absent in P. frontalis. The ovipositors of these species are quite different (compare Fig.
Paraplea lateromaculata sp. nov. can be differentiated from P. melanodera sp. nov. by their colored markings. More specifically, Paraplea lateromaculata sp. nov. has the distinctive black spots whereas P. melanodera sp. nov. has no black spots but has a black band at the posterior margin of the head. Although the size is similar between P. lateromaculata sp. nov. and P. melanodera sp. nov., recognizable differences exist in other characters as listed in their respective descriptions. Paraplea lateromaculata sp. nov. often has three pronotal black spots on the prothorax as is found in less than 10% of P. liturata; however, P. liturata has never been observed to have the black spots on the hemelytral costal margin as is seen in all specimens of P. lateromaculata sp. nov.
= Ploa liturata Fieber, 1844: Entomol. Monogr. p. 19.
= Plea liturata: (Kirkaldy, 1904): Wien. Entomol. Zeit. 23: 129.
= Plea metiadusa Distant, 1910: Fauna Brit. India 5: 337.
= Plea rufonotata Distant, 1914: Rech. Sci.N.-Calédonie 2: 387.
= Plea quinquenota Paiva, 1918: Rec. India. Mus. 14: 29.
= Plea fasciata Horváth, 1918: Ann. Mus. Nat. Hung. 16: 144.
Plea (Paraplea) liturata:
Paraplea liturata: Drake and Maldonado-Capriles 1956 (elevation to genus) 51: 53.
Paraplea liturata shares some of the same taxonomic history as P. frontalis since both were described in the same paper. Paraplea liturata was described as Ploa liturata by
Holotype. None designated.
All measurements are in millimeters and were taken from 221 adult specimens from throughout Thailand as reported in the distribution portion of this paper. Specimens used for this description are deposited at UMC and
Body size. Total length, 1.27–1.68 (average 1.48) in Thailand specimens.
Color. Color may be quite variable among individuals within a population. Base color of body ranges from tan (Fig.
Head. Head (Fig.
Pronotum
(Fig.
Wings. Complete to posterior; punctures equally spaced but not generally in rows (0.03 in diameter) (Fig.
Legs. Legs with numerous hairs and small spines (Fig.
Median ventral keel. Thoracic portions distinctly separate, prothoracic keel generally rounded, two posterior thoracic segments serrated; abdominal keel with first two segments fused, teeth more pronounced posteriorly (Fig.
Characters of female. Ovipositor most commonly as in Fig.
Characters of male. Aedeagus bulbous and somewhat asymmetrical in typical fashion of family; operculum (subgenital plate) as in Fig.
In Thailand, Paraplea liturata appears to be mostly a peninsular species on the southwest side of the country, although there are two records of it in the eastern region of Thailand; one in Sakon Nakhon Province, which was reported by
Chai Nat Province: Amphur Neon, Kham, Ban Wang Kor Hai, 14°57.934'N, 99°50.668'E, 24 V 2004, Vitheepradit & Prommi, L-710 (1 specimen UMC). Chumphon Province: Amphur Sa Wi, Tumbon Kron, 10°17.499'N, 99°05.530'E, 21 VI 2006, Vitheepradit & Prommi, L-967 (4 specimens UMC). Kalasin Province: Phu Pan National Park, 7 VI 1998, Sites, Simpson & Vitheepradit, L-165 (3 specimens UMC, 1 specimen
There is considerable variation in P. liturata if this is a single species.
A character that links all of these specimens into one species is the general state of having five spots on the pronotum. In many populations there can be specimens without these markings although the majority of specimens tend to always have five black pronotal spots. Thus, with a single specimen it may not be possible to rely on this trait but with a series of specimens it is easy to determine the species as P. liturata, as it is now defined. There appears to also be some consistency in the characters of the ovipositor. In many of the Thailand specimens, the ovipositor appears remarkably like that figured by
Ecology: The habitat of P. liturata in Thailand is typical for the majority of pleids. This species was often found in ponds, in shallow water with vegetation.
All measurements are in millimeters and were taken from 47 adult specimens from Thailand as reported in the distribution portion of this paper. Specimens used for this description are deposited at UMC and
Body size. Total length, 1.28–1.66 (average=1.49) (Fig.
Paraplea melanodera sp. nov. A female in lateral view with typical coloration. B dorsal view of a light colored morph that shows dark banding and typical minimum amount of honeycombing. C frontal view of specimens in B. D female showing a lighter colored lateral view without dark hemelytral bands.
Color. Color may vary slightly among individuals (Fig.
Head. Head generally light brown, without markings except distinctive dark band posteriorly. Antenna three-segmented. Head width at widest point including eyes 0.62–074 (average 0.68), head width at narrowest point between eyes, 0.29–0.39 (average 0.34), OI 46–52 (average 49).
Pronotum. Base color brown to light tan (Fig.
Wings. Hemelytra complete to posterior; punctures evenly dispersed with only small distance between punctures, punctures not in rows, ~ 0.02 diameter, evenly spaced (Fig.
Legs. Coxae and trochanters relatively very long compared to most pleid species (Fig.
Median ventral keel. Thoracic portions distinctively shaped but often hidden by enlarged coxa; prosternal keel broadly rounded, with irregular edges; mesosternal keel narrow, distinctive finger-like projection posteriorly; metathoracic keel segment somewhat rounded with prominent cleft towards center, sometimes appearing to almost overlap first abdominal section; abdominal keel I somewhat rectangular, with distinct tooth, abdominal keel II somewhat square, posterior tooth, abdominal keel III and IV shaped like posteriorly projecting teeth, IV longer than III (Fig.
Characters of female. Ovipositor expanded apically (Fig.
Characters of male: Aedeagus bulbous and somewhat asymmetrical in the typical fashion of family; operculum (subgenital plate), longer than wide (Fig.
Paraplea melanodera appears to be a species found only in peninsular Thailand along the west coast (Fig.
Holotype
: female, Thailand: Trang Province, Amphur Sikao, pond at Chao Mai Beach, 7°26.842'N, 99°20.647'E, 3 m, 9 I 2006, Vitheepradit and Prommi, L-907 (UMC). Paratypes (10 total): Thailand: Krabi Province: Amphur Mueang, Khlong Muang Beach, 8°02.979'N, 98°45.540'E, 13 m, 8 I 2006, Vitheepradit and Prommi, L-901 (3 paratypes UMC, 2 paratypes
Thailand, Krabi Province: Amphur Ko Lanta, Khlong Dao Beach pond, 07°38.662'N, 99°01.395'E, 10 m, 9 VIII 2005, Sites, Vitheepradit, Simpson and Prommi, L-865 (5 specimens UMC); Amphur Mueang, Khlong Muang Beach, 8°02.979'N, 98°45.540'E, 13 m, 8 I 2006, Vitheepradit and Prommi, L-901 (12 specimens UMC, 1 specimen
The specific epithet combines two Greek roots, melano- meaning black and –dero meaning the neck. Thus, the name refers the distinct dark line at the back of the head, which is distinctive of this species and a character not found in other members of the genus.
The distinctive character of P. melanodera sp. nov. is the dark band at the posterior margin of the head. This character is seen in all specimens of this species and is not observed in any other species of Paraplea. Paraplea melanodera sp. nov. also has a raised central portion of the subgenital plate in both sexes and is most pronounced in the mele. Other species of Paraplea in Southeast Asia do not have this character state. The coxae of P. melanodera sp. nov. are quite long. Paraplea lateromaculata sp. nov. also has long coxae, but are comparably shorter than those of P. melanodera sp. nov. Spines on the metathoracic femur are not common in Paraplea but are present in both P. melanodera sp. nov. and P. liturata. Paraplea melanodera also has spines on the prothoracic femur, including a couple that are longer than the others. Characters of the ventral keel, ovipositor, and subgenital plates also have distinct differences compared to other species of Paraplea.
In a study to determine the recovery of the lentic insect community following the Indian Ocean tsunami of 2004, Sites & Vitheepradit (2010) sampled ponds along the Thai coastline at four time intervals, including beginning five months after the tsunami, which marked the end of the dry season. Paraplea melanodera sp. nov. was collected in 11 of the 12 ponds inundated by the tsunami, including during the first sampling period, and in only two of the ten un-inundated reference ponds. The mean conductivity of all inundated ponds over all dates from which P. melanodera sp. nov. was collected was 1,714 μS, including one at 13,040 μS. Conductivity of the reference ponds further inland was < 100 μS and Indian Ocean seawater was over 41,000 μS. Thus, the waterbodies in which P. melanodera sp. nov. occurred had distinctly elevated levels of salinity. It is likely that P. melanodera sp. nov. also occurs further north and south along the coastlines to Burma and Malaysia.
Paraplea frontalis is one of the most widespread species of the genus and is prominent in Southeast Asia and beyond. In addition to the records reported here, P. frontalis has also been reported in other studies.
It is uncertain what factors influence the distribution of P. frontalis. The limited number of collections that represent our knowledge of this species suggest that it is most common in mainland Southeast Asia, but its distribution extends to the north into eastern Asia in China and Taiwan, west to India and Sri Lanka, and south to maritime Southeast Asia on islands of Indonesia. This paper represents the only data where an area was more thoroughly collected, although even this effort provides fewer than 500 specimens. When these collections are plotted on a distribution map (Fig.
Another factor to consider is that what is reported as P. frontalis could be a species complex. This would not pertain to the distribution shown in Fig.
Paraplea liturata is widely distributed in Thailand and some predict that it could have the largest distribution of any species in the genus (
Paraplea liturata does not appear to be restricted to any general habitat type or biogeographical region.
The distribution of P. lateromaculata sp. nov. (Fig.
The documented distribution of P. melanodera sp. nov. includes only the central part of peninsular Thailand (Fig.
RWS and AV thank Kristin B. Simpson (University of Missouri), Michael Ferro (Louisiana State University), Tang-On Prommi (Kasetsart University-Kampaeng Saen, Rathayut Sawangsak, and officers at all visited national parks and wildlife sanctuaries for their assistance in the field. We thank Nico Nieser and Dan Polhemus who provided important insights while serving as reviewers of this paper.