First Record of Two Species of Cobbonchus Andrassy, 1958

(Nematoda: Cobbonchidae) from South Kalimantan

Abdul Gafur

Department of Biology, Lambung Mangkurat University, Jalan Ahmad Yani Km. 36, Banjarbaru, Indonesia

Keywords: Biodiversity, Description, Identification, Mononchida, Predatory nematodes.

Abstract: For several decades soil nematode community structure has been used as bioindicator of soil conditions.

Because the accuracy of the assessment necessitates proper identification of existing taxa, the potential use

of nematode as bioindicator can only be realized in places where most soil nematode species have been well

identified. Previous surveys of soil nematodes in South Kalimantan (Borneo) left some specimens that were

identified as belonging to the genus Cobbonchus Andrassy, 1958, but the species was unknown. In the

present study, as a part of the South Kalimantan Nematode Biodiversity Project, the specimens were further

examined and identified as Cobbonchus collaris Andrassy, 1985 and Cobbonchus indicus Baqri, Baqri &

Jairajpuri, 1978. Despite some differences, morphological characters of the South Kalimantan specimens

generally conformed the previously published descriptions of the species. The deviations were considered

intraspecific variations that may lead to redescriptions of the corresponding species. This is the first record

of occurrence of the two species in South Kalimantan that provides new data on the geographic distribution

of the genus and species.

1 INTRODUCTION

Nematodes, in addition to prokaryotes, are the major

components of biodiversity in soil ecosystems. Not

only nematodes are the most abundant metazoans in

soils (Sohlenius, 1980; Bongers and Bongers, 1998),

nematode community is also characterized by a high

species diversity (Yeates, 1979) that most trophic

levels of the soil food web are occupied by

nematodes (Yeates et al., 1993). Therefore,

nematode diversity is indicative of general

biodiversity in the soil (Yeates and Bongers, 1999).

It has been shown that nematodes play crucial

roles in fundamental ecological processes in soils

and therefore they are correlated with soil functional

parameters and reflects soil functioning (Bongers

and Bongers, 1998; Ekschmitt et al., 2001; Hodda,

Peters and Traunspurger, 2009). This is the basis for

the using of nematode community structure as

bioindicator of soil ecological condition (Bongers,

1990).

Although in general the using of nematodes as

bioindicator of soil condition does not require

identification to species level (Bhusal et al., 2014),

more information would be obtained with species-

level discrimination (Ferris and Bongers, 2009).

Species-level identification is also necessary to

further understand the role of nematodes in soil

processes and thus in ecosystem resilience (Yeates,

2003). In regions where the nematofauna has not

been explored, such as South Kalimantan (Borneo),

inventory of soil nematodes is a prerequisite for the

using of nematodes as bioindicators. Therefore,

attempts should be made to reach species-level

identification.

In most soils mononchids comprise important

component of the nematode communities. The

predatory nematodes can be found in all kind of

soils, and in much greater number in undisturbed

soils (Ahmad and Jairajpuri, 2010).

Specimens of mononchids were collected during

a nematode ecology survey held in South

Kalimantan in 2005. The specimens were deposited

in the Nematode Collection of the Laboratory of

Biosystematics, Faculty of Mathematics and Natural

Sciences, Lambung Mangkurat University. These

were identified as belong to the genus Cobbonchus

Andrassy, 1958. However, the identification was not

continued to species.

In the present study the mononchid specimens

were further examined and described herein as

Cobbonchus collaris Andrassy, 1985 and

Gafur, A.

First Record of Two Species of Cobbonchus Andrassy, 1958 (Nematoda: Cobbonchidae) from South Kalimantan.

DOI: 10.5220/0010136800002775

In Proceedings of the 1st International MIPAnet Conference on Science and Mathematics (IMC-SciMath 2019), pages 90-95

ISBN: 978-989-758-556-2

Cobbonchus indicus Baqri, Baqri & Jairajpuri, 1978.

These are the first record of existence of the two

species in South Kalimantan, and presumably in the

Island of Kalimantan (Borneo) or even in Indonesia.

2 MATERIALS AND METHODS

In the 2005 survey specimens of mononchid

nematodes were collected by the author from

Gambut Subdistrict, Banjar District, South

Kalimantan.

The nematodes were killed and fixed in hot 4%

formalin and were transferred to pure glycerine

using rapid method of Seinhorst (1959). The

specimens were then mounted in Cobb double

coverslip slides.

Morphology of the specimens were examined

under a compound microscope (Nikon E100). A

mirrorless camera was attached to the eyepiece and

connected to a laptop. Measurements were taken

using Camera Measure Version 2.1.3.250 software

micrometer.

3 RESULTS AND DISCUSSION

3.1 Cobbonchus collaris Andrassy, 1985

3.1.1 Female (Fig. 1)

Measurements: see table 1.

Body slender, ventrally arcuate after fixation,

posterior part more curved than anterior. Cuticle

smooth. Lip region not offset from the rest of the

body, 24 μm wide. Buccal cavity thick-walled with a

narrow base, 36x15 μm, 1.5 times longer than

cephalic diameter. Stoma formed with three teeth of

nearly equal size. Dorsal tooth medium, located in

anterior half of buccal cavity; its pointed apex at

71% of buccal cavity length from base. Two

subventral teeth in posterior half of buccal cavity,

anteriorly directed apexes at 45% of buccal cavity

length from base. Pharynx cylindroid, muscular,

26% of body length. Excretory pore indistinct.

Pharyngointestinal junction non-tuberculate.

Genital system amphidelphic, anterior and

posterior branch equal in length. Vulva slightly

posterior to mid body, lips not protruding. Vagina 13

µm, about 1/3 of corresponding body width.

Distance vulva-anus 8.5 times longer than tail.

Rectum 19 µm, shorter than anal body width. Tail

short 23 µm, about 2.2 anal body width long,

uniformly tapering, with well developed caudal

glands arranged in tandem and terminal opening.

Table 1: Morphometrics of Cobbonchus collaris from

South Kalimantan.

Characters

C. collaris

(

n=1

)

Bod

len

(

)

1305

Max. bod

width

(

)

38.2

ion len

th 8.0

ion width 23.6

Buccal cavit

len

th 36.5

Buccal cavit

width 15.0

Dorsal tooth apex as % of buccal

cavit

len

th from

ase

71.2

Subventral teeth apices as % of

uccal cavit

len

th from

ase

44.9

Phar

nx len

th 346.9

Tail len

(

)

56.9

Rectum len

th 19.5

Anal bod

width

(

ABW

)

26.2

(

L/BW

)

34.2

(

L/distance anterior to 3.4

(

L/T

)

22.9

c’

(

T/ABW

)

2.2

(

L/distance anterior to vulva in %

)

58.6

%Phar

nx/L 26.6

Rectum/ABW 0.7

All measurements are in µm.

3.1.2 Male

Male not found.

3.1.3 Locality and Habitat

Specimens were recovered from a peatland covered

by ferns and Malaleuca leucadendra in Gambut

Subdistrict, Banjar District, the Province of South

Kalimantan, Indonesia.

3.1.4 Remarks

The examined specimen of Cobbonchus from South

Kalimantan population fits well the description of

Cobbonchus collaris by Andrassy (1985), except in

shorter body length (1.3 mm versus 1.6 mm), more

posterior dorsal tooth apex (29% versus 22% of

buccal cavity), shorter oesophagus relative to body

length (27% versus 29-30%), shorter rectum relative

to anal body width ( 70% versus 100%), relative

length of anterior to posterior branch of female

gonads (equal versus posterior shorter).

First Record of Two Species of Cobbonchus Andrassy, 1958 (Nematoda: Cobbonchidae) from South Kalimantan

Figure 1: Cobbonchus collaris female from South Kalimantan. A. Whole body; B. Head; C. Pharyngo-intestinal junction;

D. Gonad; E. Tail. Scale bar applies to B-E.

IMC-SciMath 2019 - The International MIPAnet Conference on Science and Mathematics (IMC-SciMath)

On the other hand, it conforms the description of C.

macrampulla by Orselli and Vinciguerra (2007) in

body length, position of dorsal tooth apex, and

rectum length relative to anal body width.

The uniformly narrowing tail agrees best with

those of C. collaris, C. macrampulla, C. palustris,

and C. radiatus. However, the examined specimen

does not show the large, sclerotized ampulla at the

end of the caudal glands typical of C. macrampulla,

the rounded lip region of C. palustris, and the offset

head of C. radiatus. Furthermore, the caudal glands

of the examined specimen are larger than those of C.

radiatus. However, comparison with C. radiatus can

not be thoroughly made as the description of the

species was based on a single young adult female

(Clark, 1960) and it is considered species inquirenda

(Andrássy, 1985). It is concluded that the examined

specimen belongs to a population of C. collaris and

the differences in some morphometrics are here

considered intraspecific variations.

3.2 Cobbonchus Indicus, Baqri, Baqri and

Jairajpuri, 1978

3.2.1 Female (Fig. 2)

Measurements: see table 2.

Body slender, posterior half strongly curved

ventrally after fixation. Head offset. Amphids cup-

shaped, with slit-like apertures close to anterior end

of stoma. Buccal cavity 26x11, anterior end arching

inwards, posterior end somewhat pointed. Dorsal

tooth apex at circa 18 um or 67% from base of

stoma; subventral teeth smaller than dorsal, their

apices at about 9 um or 35% from base of stoma.

Oesophago-intestinal junction non-tuberculate.

Excretory pore indistinct.

Reproductive system amphidelphic. Vulva at

posterior half of body, about two third of body

length. Vagina sclerotized distally, extending

inwards up to half of corresponding body width.

Ovaries reflexed. Tail short conoid, rather bulbous,

slightly ventrally curved, 0.8 anal body-width long.

Rectum equal to or slightly longer than anal body

width. Caudal glands well developed; opening

subdorsal.

3.2.2 Male

Male not found.

3.2.3 Locality and Habitat

Specimens were collected from a peatland covered

by ferns and Malaleuca leucadendra in Gambut

Subdistrict, Banjar District, the Province of South

Kalimantan, Indonesia.

3.2.4 Remarks

The specimens of Cobbonchus examined agree with

general morphology of Cobbonchus indicus as

described by Baqri et al. (1978), except in some

morphometric details. The South Kalimantan

specimens are slightly longer (body length 1.16-1.30

mm versus 1.07 mm). Dorsal tooth apex is more

posterior (65-70% versus 78% from base of stoma).

Tail is shorter (16-24 versus ca 30 µm), mainly

because of the shorter finger-like projection.

Despite the differences, the specimens from South

Kalimantan are considered to belong to a population

of Cobbonchus indicus. This is a new record of

existence of this species in South Kalimantan and

Indonesia, and even outside the type locality in

India.

Table 2: Morphometrics of Cobbonchus indicus from

South Kalimantan.

Characters

C. indicus

(n=3)

Body length (L) 1165 – 1360

Max. body width 30.5 – 41.3

Lip region length 3.7 – 4.7

Lip region width 17.8 – 20.7

Buccal cavity length 25.9 – 27.0

Buccal cavity width 10.5 – 12.6

Dorsal tooth apex as % of buccal

cavit

len

th from base

64.9 – 70.0

Subventral teeth apices as % of

uccal cavity length from base

32.8 – 40.4

Pharynx length 324.9 – 354.4

Tail length (T) 17.5 – 21.9

Rectum length 20.9 – 29.8

Anal body width (ABW) 21.0 – 24.3

a (L/max body width) 32.9 – 38.2

b ( 3.3 – 3.5

c 62.1 – 71.1

c’ 0.8 – 0.9

V 65.4 – 67.4

%Pharynx/L 26.1 – 27.9

Rectum/ABW 1.0 – 1.2

All measurements are in µm.

First Record of Two Species of Cobbonchus Andrassy, 1958 (Nematoda: Cobbonchidae) from South Kalimantan

Figure 2: Cobbonchus indicus female from South Kalimantan. A. Whole body; B. Head; C. Pharyngo-intestinal junction; D.

Tail; E. Gonad. Scale bar applies to B-E.

IMC-SciMath 2019 - The International MIPAnet Conference on Science and Mathematics (IMC-SciMath)

4 CONCLUSIONS

Specimens of Cobbonchus in the nematode

collection of Laboratory of Biosystematics, Faculty

of Mathematics and Natural Sciences, Lambung

Mangkurat University have been identified as

Cobbonchus collaris and Cobbonchus indicus. This

is the first report of existence of the two species in

South Kalimantan and in Indonesia.

ACKNOWLEDGEMENTS

The present study was financially supported by The

Faculty of Mathematics and Natural Sciences

Lambung Mangkurat University.

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First Record of Two Species of Cobbonchus Andrassy, 1958 (Nematoda: Cobbonchidae) from South Kalimantan