Journal Search Engine
Search Advanced Search Adode Reader(link)
Download PDF Export Citaion korean bibliography PMC previewer
ISSN : 2288-1115(Print)
ISSN : 2288-1123(Online)
Korean Journal of Ecology and Environment Vol.54 No.2 pp.125-129
DOI : https://doi.org/10.11614/KSL.2021.54.2.125

Fundamental Morphological Study of 16 Genera of Chironomid Larvae in Korea

Dong Ju Lee, Jae-won Park1, Ihn-Sil Kwak1*
Department of Life Science, Silla University, Busan 46958, Republic of Korea
1Department of Ocean Intergrated Science, Chonnam National University, Yeosu 59626, Republic of Korea
* Corresponding author: Tel: +82-61-659-7148, Fax: +82-61-659-7149 E-mail: iskwak@jnu.ac.kr
25/05/2021 16/06/2021 21/06/2021

Abstract


Chironomids are a large group of invertebrates that live in various aquatic habitats. The distribution range of these invertebrates has become varied due to anthropogenic impacts; as such, their distribution can be used as an indicator of environmental health. Adult chironomids are well known in South Korea; however, the larvae have rarely been studied due to difficulties associated with morphological classification. To address this lack of information, we collected larvae from four important rivers in South Korea and summarized their taxonomic morphological characteristics. The antennae, mandible, and mentum were used for larval taxonomic characterization. In this study, we describe the basic morphological features and key pictorial features of 20 species of chironomids, representing 16 genera.



초록


    INTRODUCTION

    Chironomids have an important role in the food network of aquatic communities, representing a major link between producers and secondary consumers (Tokeshi, 1995). Chironomidae is a large group of invertebrates found in various water worldwide, with a reported diversity of 8,000~20,000 species (Armitage, 2012). Although adult chironomids inhabit areas near the riparian zone of rivers or lakes, the larvae are aquatic organisms distributed in diverse aquatic habitat patches (Pinder 1986, 1995). Chironomid larvae was potentially represent more than 70% abundance of the total arthropod numbers in hypersaline waters and are opportunistic omnivores, ingesting a wide variety of food sources (Cummins and Klug, 1979). In general, these larvae ingest five kinds of food such as algae, detritus and associated microorganisms, macrophytes, wood debris, and other invertebrates (Berg, 1995). Moreover, recent eDNA metabarcoding-based gut content analysis of chironomid larvae indicated the presence of various small planktons, such as Desmodesmus armatus, Eolimna minima, and Tetradesmus dimorphus, in the weirs (Jo et al., 2020).

    Kwak (2015) introduced 24 genera and 43 species of chironomid larvae based on visibly identified taxonomical adult stages in South Korea. The morphological studies of larvae are scarce: Yoon and Chun (1992) described the abdomen characteristics through simple drawings of eight Chironomus larval species. Ree (1981, 1998) described the larva of Cricotopus oryzaphagos. In this study, we provide the detailed pictorial features and morphological keys to 16 genera present in Korea.

    MATERIALS AND METHODS

    Chironomid larvae were collected from four important freshwater rivers in South Korea from April to June in 2018 and 2019. Collections were made using a Ponar grab (20 cm×25 cm) and a sieve (mesh size: 500 μm). The samples were fixed and preserved using 90% ethanol and about 16.9℃ (range: 8.76~23.35℃) the field water temperature was measured using portable equipment (Model: YSI Professional Plus, Ohio, USA).

    Specimens were dissected and the dissected parts were mounted on slides using a glycerol mounting medium. The dissection was performed on a glass slide under a microscope (Olympus SZX12). The body was dissected with a needle and appendages were used to prepare the slides. The sandwich method was used for setting the position and rotating the specimen. The permanent mount slide was sealed with transparent nail varnish. All drawings were made using a drawing tube on an Olympus BX51 differential interference contrast microscope. The descriptive terminology follows Epler (2001).

    RESULTS AND DISCUSSION

    A total of 16 genera and 20 species were identified from four major rivers in Korea (Table 1). The classification criteria were determined according to the morphological characteristics. Chironomid larvae have a cylindrical body shape and are well-segmented. Some appendages located on head capsule and posterior part is very important for identification.

    1. Major pictorial characteristics of chironomid larvae

    1) Antenna (Fig. 2)

    The antenna is located in the front of the head capsule (Fig. 1), with a possibility of putting it in and out. The shape and length are diagnostic for many taxa. In general, the characteristic is used for identification by segment number and ratio. This is the length of the basal segment divided by the remaining segments. The placement and shape of the Lauterborn organ sensory structures often located on the second seg- ment or at its apex are important, as is the location of the ring organ.

    2) Mandible (Fig. 3)

    The mandible is located on the right and left side of the body at the front of the head capsule (Fig. 1). Strong teeth are located foremost, which used for holding on tightly to food. Several complex characteristics was used for identification, including the number and shape of the inner apical teeth, the present or absence of a seta interna, the morpho-type of seta subdentalis, and the pectin mandibularis.

    3) Mentum (Fig. 4)

    The strong teeth with ventromental plates are located at the center of the head capsule. The shape and number of teeth are the most important characteristics for identification. The shape of the ventromental plate and the presence or absence of a beard are noticeable features.

    2. Morphological key for the 16 genera of the chironomid larvae in South Korea

    • 1. Posterior parapods long, relatively; the ratio of length/ width of the head capsule is 1.5~2.0 times ...................... .............................................. (Tanypodinae) ··················· 2

    • - Posterior parapods short; the ratio of length/width of the head capsule is 1.0 to 1.3 times ........................................ ................. (Chironominae / Orthocladinae) ··················· 3

    • 2. The shape of the ligular teeth is V-shaped type (Fig. 5A) ························································ genus Conchapelopia

    • - The shape of the ligular teeth is aligned (Fig. 5B) ············ ·································································· genus Tanypus

    • 3. Antenna extremely elongated (Fig. 6A); Mandible with 1 to 2 apical teeth ······························································ 4

    • - Antenna not elongated (Fig. 6B) ···································· 5

    • 4. The first segment of the antenna with a seta, located in the middle part of the segment ············· genus Tanytartus

    • - First segment of the antenna without seta ························· ···························································· Tokunagayu surika

    • 5. Labrum with naked or simple seta ································· 6

    • - Labrum with plumose seta ············································· 8

    • 6. Ring organ in antenna located above 1/2 (Fig. 6C) ········ 7

    • - Ring organ in antenna located under 1/2 (Fig. 6D) ··········· ········································································ genus Chaetocladius, genus Cricotopus*, genus Diplocladius, Einfeldia dissideus, genus Glyptotendipes, Orthocladius suspensus

    • * - The ratio of the first segment of the antenna is not long (about 3.5 times) ·········································· C. sylvestris

    • - The ratio of the first segment of the antenna is long (about 10 times) ················································· C. oryzaphages

    • 7. The mentum is a plate-type (Fig. 7A) · genus Harnischia

    • - The mentum is a V-shaped type (Fig. 7B) ························· ················································· genus Cryptochironomus

    • 8. Antenna with 5-segmented ··········································· 9

    • - Antenna with 6-segmented ········································· 10

    • 9. Tubules presented; Mentum teeth is 6 : 3 : 6 (Fig. 8A) ······· ······················································· genus Chironomus**

    • - Tubules absent; Mentum teeth is 6 : 2 : 6 (Fig. 8B) ·········· ···················································· Polypodium scalaenum

    • ** includes Chironomus kiiensis, C. flaviplumus, C. sp.

    • 10. Median part of mentum is pale ······· genus Microtendipes

    •  - Median part of mentum is dark ··· genus Stictochironomus

    3. Taxonomic account

    1) Subgenus Tanypodinae

    Diagnosis. Posterior parapods long. The ratio of length/ width of the head capsule is 1.5 to 2.0 times. Antenna 4-segmented, retractile into the head capsule, Anal tubules usually well developed in Korean freshwater species. Genus Conchapelopia and Tanypus can easily be distinguished by the shape of the ligular teeth.

    Ecology. This subfamily consists of free-swimming or crawling predators; some burrow in the bottom mud. Conchapelopia and Tanypus are identified and recognized from different water temperature. Conchapelopia is found at a high temperature (19.80℃), Tanypus punctipennis is a low (9.30℃).

    2) Subgenus Chironominae

    Diagnosis. Posterior parapods short. The head capsule is mostly of the same aspect ratio (1.0 to 1.3 times). Antenna usually 4 to 6-segmented. Mentum teeth is 6 : 3 : 6, well sclerotic teeth, sometimes reduced. Anal tubules usually present.

    Ecology. The most abundant subfamily in South Korea. 9 genera and 11 species are recognized. According to Epler (2001), this group also inhabits brackish and marine water. Most larvae build tubes using sediment. The genus Chironomus has hemoglobin, exhibits a red color, and could survive in low oxygen conditions. The Chironomus species occur under ordinary temperature conditions (15~22℃) in April and May. Three species were identified C. kiiensis, C. flaviplumus, C. sp. Species of genera Microtendipes and Tanytarsus could occur under low temperature conditions in early spring.

    3) Subgenus Orthocladinae

    Diagnosis. Posterior parapods short, sometimes reduced. Antenna with 3~7 segments; sometimes strongly reduced or could be longer than the head capsule. Mentum well sclerotized. There are two recognized Cricotopus species that could be easily identified by the ratio of the first antennal segment.

    Ecology. Orthoclad larvae are found in a variety of freshwater habitats. Most larvae are scrapers, collectors. Five genera and 7 species have been recognized in this study. These species are found in the spring season (March to June) and can survive at 13℃.

    저자정보

    이동주 (신라대학교 생명과학과 겸임교수), 박재 원 (전남대학교 해양융합과학과 석사과정), 곽인실 (전남대 학교 해양융합과학과 교수)

    저자기여도

    개념설정: 곽인실, 방법론: 곽인실, 이동주, 박재 원, 분석: 곽인실, 이동주, 자료제공: 곽인실, 자료관리: 곽인실, 원고 초안작성: 곽인실, 이동주, 박재원, 원고 교정: 곽인실, 이 동주, 박재원, 원고 편집 및 검토: 곽인실, 이동주, 박재원, 과제 관리: 곽인실, 연구비 수주: 곽인실

    이해관계

    이 논문에는 이해관계 충돌의 여지가 없음.

    연구비

    본 연구는 한국연구재단 [NRF-2018R1A6A1A030 24314]과 [NRF-2020R1A2C1013936]의 지원을 받아 수행 된 연구입니다.

    Figure

    KSL-54-2-125_F1.gif

    The general morphological structure of chironomid larvae (A) and the main locations of the ventral head capsule (B).

    KSL-54-2-125_F2.gif

    Basic structure of the antenna in the head capsule (Einfeldia dissidnus).

    KSL-54-2-125_F3.gif

    Basic structure of the mandible in the head capsule (Chironomus sp.).

    KSL-54-2-125_F4.gif

    Basic structure of the mentum in the head capsule (Dipocladius sp.).

    KSL-54-2-125_F5.gif

    Representative structure of the ligular in the head capsule. (A) Conchapelopia sp., (B) Tanypus sp.

    KSL-54-2-125_F6.gif

    Representative structure of the antenna in the head capsule. (A) Chironomus sp., (B) Tanytartus sp., (C) Chaetocladius sp., (D) Cryptochironomus sp.

    KSL-54-2-125_F7.gif

    Representative structure of the mentum in the head capsule. (A) Harnischia sp., (B) Cryptochironomus sp.

    KSL-54-2-125_F8.gif

    Representative structure of the mentum in the head capsule. (A) Polypodium scalaenum, (B) Chironomus sp.

    Table

    List of the 16 genus of Chironomids in South Korea.

    Reference

    1. Armitage, P.D. , L.C. Pinder and P.S. Cranston.2012. The Chironomidae: biology and ecology of non-biting midges. Springer Science & Business Media.
    2. Berg, M.B. 1995. Larval food and feeding behaviour. In: The Chironomidae (Armitage, P.D., P.S. Cranston and L.C.V. Pinder, eds.). Springer, Dordrecht, pp. 136-168.
    3. Cummins, K.W. and M.J. Klug.1979. Feeding ecology of stream invertebrates. Annual Review of Ecology and Systematics 10: 147-172.
    4. Epler, J.H. 2001. Identification manual for the larval Chironomidae of North and South Carolina. USEPA Grant.
    5. Jo, H.B. , B.H. Choi, K.Y. Park, W.S. Kim and I.S. Kwak.2020. First Gut Content Analysis of 4th Instar Midge Larvae (Diptera: Chronomidae) In Large-Scale Weirs Using a DNA Meta-Barcoding Approach. International Journal of Environmental Research and Public Health 17: 2856.
    6. Kwak, I.S. 2015. Introduction to the Chironomidae as a water pollution indicator. Chonnam National University Press, pp. 13-156.
    7. Pinder, L.C.V. 1986. Biology of freshwater Chironomidae. Annual Review of Entomology 31: 1-23.
    8. Pinder, L.C.V. 1995. The habitats of chironomid larvae. In: The Chironomidae (Armitage, P.D., P.S. Cranston and L.C.V. Pinder, eds.). Springer, Dordrecht, pp. 107-135.
    9. Ree, H.I. 1981. Studies on Korean Chironomidae (Diptera) 2. Description of a New Genus and a New Species of Chironomidae. Korean Journal of Zoology 24: 217-220.
    10. Ree, H.I. and J.Y. Kim.1998. A New Species of the Genus Cricotopus (Diptera: Chironomidae), a Pest of Rice in Seosan, Korea. Korean Journal of Biological Sciences 2: 309-313.
    11. Tokeshi, M. 1995. Life cycles and population dynamics. In: The Chironomidae(Armitage, P.D., P.S. Cranston and L.C.V. Pinder, eds.). Springer, Dordrecht, pp. 225-268.
    12. Yoon, I.B. and D.J. Chun.1992. Systematic of the Genus Chironomus (Diptera: Chironomidae) in Korea. Entomological Research Bulletin 18: 1-14.