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NATURA MONTENEGRINA, Podgorica, 2011, 10(4): 425-434

SCANNING ELECTRON MICROSCOPIC OBSERVATIONS OF Copidognathus arabicus CHATTERJEE & CHANG (ACARI, HALACARIDAE) AND NOTES ON THE DISTRIBUTION OF THE Copidognathus bairdi GROUP SENSU LATO IN THE INDIAN OCEAN Tapas C H A T T E R J E E 1 and Bhikari Charan G U R U 2 1 Department of Biology, Indian School of Learning, I.S.M. Annexe, P.O.-I.S.M. Dhanbad 826004, Jharkhand, India. E-mail: [email protected] 2 Deartment of Zoology, Utkal University, Vani Vihar, Bhubaneswar 751004, Orissa, India. Email: [email protected]

Key words: Copidognathus arabicus, SEM, bairdi group, distribution, India, Indian Ocean.

SYNOPSIS

Scanning Electron microscopic observations of some characters of Copidognathus arabicus Chatterjee & Chang is presented. Distribution of the species, belonging to the C. bairdi group sensu lato, in the Indian Ocean is also discussed.

INTRODUCTION Copidognathus arabicus Chatterjee & Chang, 2004 was first described from

Mumbai coast of India (Chatterjee & Chang, 2004). Dovgal et al. (2008) reported suctorian ciliates Praethecacineta halacari (Schulz, 1933) as epibionts on C. arabicus from Goa, India. In the present paper, the morphology of C. arabicus is studied in detail, based on scanning electron microscopic observations of specimens from Goa, India. C. arabicus belongs to the bairdi group sensu stricto. Distribution of the bairdi group sensu lato from the Indian Ocean is also provided.

MATERIAL AND METHODS Specimens were collected from Anjuna beach and Vagator beach of Goa, west

coast of India (Arabian Sea) among mixed intertidal samples of algae and sediment. Specimens for scanning electron microscopy were prefixed overnight at 4°C in 2.5% glutaraldehyde, followed by post fixation in 2% cold osmium tetraoxide. After

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dehydration in a graded series of ethanol solutions (50- 100% with specimens kept for 30 min at each 10% increase in concentration), the material was dried in the critical point dryer, and coated with gold-palladium in a high evaporator. They were then examined with a scanning electron microscope.

The following abbreviations are used in the text and figure legends: AD-anterior dorsal plate; GO-genital opening; OC-ocular plate(s); PAS-parambulacral seta(e); PD-posterior dorsal plate; PE-posterior epimeral plate(s).

RESULTS AND DISCUSSION Copidognathus arabicus Chatterjee & Chang, 2004 (Figs. 1-5) Copidognathus arabicus Chatterjee & Chang 2004, 267-269, Figures 3, 4. The original description of this species is given in Chatterjee & Chang, 2004.

Some characters referred to species in that paper are described in more details according to the present SEM study.

Areolae and costae on dorsal plates with rosette pores. Each rosette pore with an ostium and very fine canliculi. AD with one oblong anterior areola, two middle areolae pyriform (some times crescent shaped), and one marginal posterior areolae. PD with four costae, middle costae three rosette pores wide, lateral costae two rosette pores wide; middle and lateral costae join anteriorly. Proto- and deutorostral setae situated at tip of rostrum, tritorostral setae (long maxillary setae of rostrum) at the anterior half of rostrum, gnathosomal base with a pair of setae (basirostral setae). Telofemur I with narrow outermost ventrolateral lamella. Genu IV with four setae. Tibia I with one pointed ventrolateral smooth seta, one pointed ventromedial smooth seta distally and one small blunt ventromedial smooth seta proximally. Tibia II with one long, smooth ventral seta and two thick, pectinate ventromedial setae. Tibia III with one thick, pectinate ventromedial seta. All setae of tibia IV smooth. Tarsi III and IV with four dorsal setae, distance between two basidorsal setae of tarsi III and IV subequal with height of the segment. Tarsi I-II each with two doublet eupathid PAS. On tarsus III lateral PAS seta like and medial PAS flattened.Tarsus IV with both PAS small flattened pectinate. All legs with two lateral claws and one bidentate median claw. Lateral claws with accessory process dorsally. Lateral claws of tarsus I smooth ventrally. Lateral claws of tarsi II-IV larger than those of tarsus I, furnished with well developed ventral pecten.

Many specimens were infested with epibiont suctorian ciliates Praethecacineta halacari (Schulz, 1933).

Chatterjee & Guru: SC ANNING ELECTRON MICROSCOPIC OBSERVATIONS OF . . .

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Figure 1 : Copidognathus arab icus Chat ter jee & Chang; A: Habi tus dorsa l ; B: par t o f AD, OC and PD; C: AD, OC and PD; D: Magni f ied view of middle areo lae on AD; E: par t o f PD

show ing costae; F : Magni f ied view of roset te pores o f middle areo la on AD. (Sca le bars : A=100 µm, B ,C , E=50 µm, D=20 µm, F=5 µm) .


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Figure 2 : Copidognathus arab icus Chat ter jee & Chang, female; A: Habi tus ven t ra l ; B : Par t o f a reo la on PE; C: C i l ia tes at tached w i th id iosoma vent ra l ; D: GO; E: Par t o f

Ana l a rea; F: Gnathosoma. (Scale bars : A = 200 µm, B = 10 µm, C = 50 µm, D -F= 20 µm).


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Figure 3 : Copidognathus arab icus Chat ter jee & Chang, female; A: Legs I & I I ; B and C: T ip o f ta rsus I ; D: Par t o f t ib ia I I show ing pect inate se tae; E and F: T ip o f ta rsus I I .

(Sca le bars : A=50 µm, B ,D=20 µm, C , E , F=10 µm) .


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Figure 4 : Copidognathus arab icus Chat ter jee & Chang, female; A: leg I I I ; B : Par t o f t ib ia I I I Show ing pect inate seta ; C: T ip o f ta rsus I I I ; D and E: leg IV; F : Tarsus IV .

(Sca le bars : A = 100 µm, B = 10 µm, C = 20 µm, D , E = 50 µm, F = 20 µm) .


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Figure 5 : Copidognathus arab icus Chat ter jee & Chang, female; A: Par t o f a reo la near postero la tera l s ide on GA; B: Par t o f gnathosoma; C: Te lo femur I (nar row outermost

vent ro la tera l lamel la ind icated by ar row ) and genu I ; D: Leg IV (a r row indicat ing 4 se tae on genu IV ) ; E : T ib ia I (d is ta l vent romedia l se ta ind icated by ar row 1 , prox imal

vent romedia l se ta ind icated by ar row 2 , vent ro la tera l se ta indicated by ar row 3 ) ; F : Tarsus I (P AS ind icated by ar row ) .

(Sca le bars : A, F= 5 µm, B , C= 10 µm, C = 10 µm, D , E = 20 µm) .


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DISTRIBUTION OF THE BAIRDI GROUP SENSU LATO IN THE INDIAN OCEAN: There are many species groups in the genus Copidognathus. One of such

groups is the bairdi group (Newell, 1947; Bartsch, 1984, 1996, 1997). Characteristics of the bairdi group are “PD with two or four longitudinal costae with rosette pores and two pairs of prominent gland pores; ovipositor only slightly extending beyond GO; spermatopositor large, extending beyond GO for length of GO; genu IV with four setae” – Bartsch (1997).

Bartsch (1997) subdivided the bairdi group into five subgroups viz. bairdi group s. str., ornatus group, spinula group, temaeus group and gibberipes group.

Five species of the bairdi group s. str. are recorded from the Indian Ocean. C. africanus Bartsch, 1972, which was reported among algae and sand on the sea shore near Knysna, South Africa (Bartsch, 1972). Konnerth-Ionescu (1977) reported C. africanus among Acropora palmate and coarse sand, from Kunduchi, Tanzania. C. sideus Bartsch, 1982 was reported from Mozambique channel (Bartsch, 1982) and eastern and western coast of India (Chatterjee & Sarma, 1993). C. andamanensis Chatterjee & De Troch, 2003 was reported from Chiriatapu, Andaman Islands, India (Bay of Bengal) (Chatterjee & De Troch, 2003) among the sediments associated to the coral algae Halimeda opuntia. Bartsch (2009) wrongly wrote this species name as ”Copidognathus andamensis Chatterjee & De Troch, 2003” in the species list of halacarid mites. Chatterjee & Chang (2004) reported C. arabicus Chatterjee & Chang, 2004 from Mumbai, India among algae and sediments associated with rocks. C. ungujaensis Chatterjee, De Troch & Chang, 2006 was recorded from Matemwe, the east coast of Unguja, Zanzibar, Tanzania (Chatterjee et al. 2006) among coralline sediments of Fungia. Proches & Marshall (2002) recorded C. bairdi Newell, 1947 from southern and southeastern Africa but according to Bartsch (2009) “A record of C. bairdi from South Africa (Proches & Marshall 2002) is most likely one of C. africanus Bartsch, 1972”, we agree with Bartsch (2009).

C. gitae Chatterjee, 1991 a member of the spinula group (a subgroup under the bairdi group s. l.) was reported among algae from Palm beach, Visakhapatnam, Andhra Pradesh (Chatterjee, 1991; Chatterjee & Annapurna, 2003).

C. ornatus Bartsch, 1981 is a member of the ornatus group (a subgroup under the bairdi group s. l.) was recorded from Mozambique Channel (Bartsch, 1981)

C. temaeus Bartsch, 1992 was reported among coralline algae Jania rubens from Chatam island, Andaman islands (Chatterjee, 1996). This is a member of the tameus group (a subgroup under the bairdi group s. l.). C. fungiae Chatterjee, De Troch & Chang, 2006 a member of the tameus group was described from Matemwe, the east coast of Unguja, Zanzibar, Tanzania (Chatterjee et al., 2006) among coralline sediments of Fungia.

C. meridianus Bartsch, 2003 was reported from sandy deposits at Dampier, Western Australia (Bartsch, 2003). “C. meridianus is a member of the bairdi group,


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though it cannot be attributed to any of the subgroups” - Bartsch (2003). It is also the first arenicolous species of this group.

C. pseudosidellus Chatterjee, 1997, reported from Andaman Islands (Chatterjee, 1997) shows similarity to C. sidellus Bartsch but does not belong to the bairdi group. It possesses three setae on genu IV, whereas four setae are found on this structure in the bairdi group of species.

Of the ten species belonging to the bairdi group s. l. from the Indian Ocean, two species, C. ornatus and C. temaeus, are also found in other oceanic regions. C. temaeus was reported from Moorea, Bora Bora, Society Islands, western Pacific and C. ornatus from Great Barrier reef, Australia, western Pacific (Bartsch, 1992; Otto, 2001). Furthermore, all of the species are found in the intertidal or subtidal zones. However, C. sideus has a broad ecological distribution and occurs in both the intertidal and at the depth of 110-440 m.

Species of the bairdi group are known from both the tropical and warm temperate regions.

A more extensive faunistic survey covering a greater part of the Indian Ocean is likely to lead to an increase in the number of species in the bairdi group from this region.

ACKNOWLEDGEMENT

We are very much thankful to Dr. Benny K K Chan, Academia Sinica, Taiwan for making the

SEM photos of these mites and for helping final arrangement of the plates. Thanks are due

to Dr David J Marshall, Universiti Brunei Darussalam, for English linguistic help.

REFERENCES:

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Hamburgischen Zoologischen Museum und Institut, 69: 5–32. BARTSCH, I. 1981: Halacaridae (Acari) aus dem Kanal von Moçambique. – Cahiers de

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BARTSCH, I. 2003: A new arenicolous Copidognathus (Halacaridae: Acari) from Dampier, Western Australia. Western Australian Museum, Perth. In: Wells, F.E., Walker, D.I. & Jones, D.S. (Eds), The Marine Flora and Fauna of Dampier, Western Australia. - Western Australian Museum, Perth, pp. 281–289.

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Received: 27 October 2011.

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