A taxonomic revision of some previously described species of monogenoideans found on Indian Siluriform fishes

Abstract

A Taxonomic revision of. Bychowskyella bagariusi Sharma, 1983 and Bychowskyella singhi Rajeshwari & Kulkarni, 1983 Jain, 1952 found on Indian Siluriform fishes is being done in the present work. These species were considered as species inquirenda or nomen nudum, (Lim et al. Syst Parasitol 50:159–197, 2001) and thus, their taxonomical clarification was required Among them, B. bagariusi Sharma, 1983 from Bagarius bagarius (Hamilton) is considered as valid and B. singhi Rajeshwari & Kulkarni, 1983 from Wallago attu (Bloch & Schneider), belongs to the genus Thaparocleidus Jain, 1952.

Introduction

The genus Bychowskyella Achmerov (1952) (syns: Silonditrema Tripathi; Sprostonia Jain; Neosprostonia Jain; Clariotrema Long; Neobychowskyella Ma, Wang & Li) was established by Achmerov (1952) with Bychowskyella pseudobagri Achmerov, 1952 as its type species from bagrid fishes of the Amur-Chinese region of China. To date, this genus comprises 32 species, reported from South East Asia, parasitizing 28 catfish species of 15 general Lim et al. (2001). Among these, 22 species have been reported from India; infesting cat-fishes of the families: Clariidae, Siluridae & Sisoridae of the order Siluriformes.

During the present investigation on monogenoidean parasites of Indian Siluriforme fishes, it was understood that diagnosis of some previously described species of Bychowskyella is incomplete, as it is primarily based on illustration of hard parts alone. Some were misidentified at generic and specific level based on minor morphological variations, demanding further examination of type specimens. Also, in almost all the cases, the type-material was either in poor condition or not available. In addition, (Lim et al. 2001), in their exhaustive review of monogenoidean parasites of siluriform fishes from Old World, considered only 17 Indian species of Bychowskyella as valid and five species either species inquirenda or nomen nudum (Table 1). This paper reviews the taxonomy of Indian species of Bychowskyella. The genus Bychowskyella is characterized by the presence of three pairs of hooks with dilated proximal handles (henceforth referred to as large hooks) others of larval types (henceforth referred to as small hooks) and two additional rodlike sclerites one on either side of dorsal anchors; two dorsal anchors without roots, stout base, long shaft, long recurved patches; two ventral anchor without roots, with stout base, dorsal connective bar almost straight, fenestrated in middle and, ventral bar paired (Lim et al. 2001).

Table 1.

List of Indian species of the genus Bychowskyella (Lim et al. 2001)

Indian species of the genus Bychowskyella	Status	Hosts
B. asiatica (Jain, 1959) Gusev, 1961	Valid	Ompok pabda (Ham. 1822)
B. wallagonia (Jain, 1959) Gusev, 1961	Valid	Wallago attu (Bl.& Sch., 1801)
B. gomtia (Jain, 1959) Gusev, 1961	Valid	Eutropiicthyes vacha (Ham. 1822)
B. indica (Jain, 1959) Gusev 1961	Valid	Eutropiicthyes vacha (Ham. 1822)
Syn: B.garuai (Agrawal &Singh, 1982) Agrawal & Sharma, 1990		Clupisoma.garua (Ham. 1822)
B. gharui (Tripathi, 1959) Gusev, 1961	Valid	Lupisoma.garua (Ham. 1822)
Syn: B. gussevi Majumdar & Agarwal, 1989		Clupisoma.garua (Ham. 1822)
B. vacha (Tripathi, 1959) Gusev, 1961	Valid	E. vacha (Ham. 1822)
Syn: B. lucknowensis Agrawal & Sharma, 1990	–	E. vacha (Ham. 1822)
B. cauveryi (Tripathi, 1959) Gusev, 1961	Valid	Silonia silondia (Ham. 1822)
B. bychowskii Gusev, 1977	Valid	Pseudotropius takree
B. caballeroi Gusev, 1977	Valid	C.garua (Ham. 1822)
B. chauhani Venkatanarsaiah, 1989	Valid	W. attu (Bl.& Sch., 1801)
B. raipurensis Majumdar & Agarwal, 1989	Valid	Rita-rita (Ham. 1822)
B. pricei Majumdar & Agarwal, 1989	Valid	C. garua (Ham. 1822)
B. fossilisi Majumdar & Agarwal, 1989	Valid	Heteropneustes fossilis (Bloch, 1794)
B. kanpurensis Agrawal, Shukla & Vishwakarma,1996	Valid	Ompok bimaculatus (Bloch, 1794)
B. jaini Agrawal, Shukla & Vishwakarma,1996	Valid	C. garua (Ham. 1822)
B. tchangi Gusev, 1976	Valid	Clarius batrachus
B. tripathii Kumar & Agrawal, 1981 [originaly ntioned as Silonditrema tripathai Kumar & Agrawal, 1977 nomen nudum]	Valid	W. attu (Bl.& Sch., 1801)
B. bagariusi Sharma, 1987	Sp.Inq.	Bagarius bagarius (Ham., 1822)
B. singhi Rajeshwari & Kulkarni, 1983	Sp.Inq.	W. attu (Bl.& Sch., 1801)
Silonditrema kanpurensis Gupta & Sachdeva, 1986	Sp.Inq.	Mystus tengara (Ham. 1822)
Silonditrema ritai Gupta, 1986	Sp.Inq.	Rita-rita (Ham. 1822)
Neosprostonia garuai Agrawal & Singh, 1982	Sp. Inq.	C. garua (Ham. 1822)

Materials and methods

The hosts fishes were collected from Gomti River, Lucknow and adjoining areas. The worms, collected from gills, were studied mostly live under a phase contrast microscope or after being fixed in 3 % formalin diluted with lukewarm water. The methods of staining, mounting, and illustrating the dactylogyrids were based on Kritsky et al. (1986). Measurements were taken using a calibrated micrometer, and are given in micrometers (μm) with the mean followed by the range and the number (n) of specimens measured in parentheses. Unstained, unflattened specimens were used to obtain the measurements of the internal organs (pharynx and gonads), the body and the haptoral sclerites. Illustrations were prepared with the aid of a camera lucida attached to a phase-contrast microscope. Host name follows FishBase (Froese and Pauly 2007).

Voucher specimens were deposited in the ZSI, Kolkata.

Results

Class Monogenoidea Bychowsky, 1937

Order: Dactylogyridea Bychowsky, 1937

Fam: Dactylogyridae Bychowsky, 1933

Genus: Bychowskyella Achmerov, 1952

Species: Bychowskyella bagariusi Sharma, 1983 (Figs. 1, 2–8b)

Fig. 1.

Bychowskyella bagariusi Sharma, 1987 (ventral view)

Figs. 2–8b.

Bychowskyella bagariusi Sharma, 1987. 2 Dorsal anchor. 3 Patch. 4 Ventral anchor.5 Ventral bar. 6 Dorsal bar. 7 Hooks. 8 Onchium. 8a Sclerite. 8b Copulatory complex

Previous host record and locality: Host: The Devil catfish or dwarf goonch, Bagarius bagarius (Hamilton) (Siluriformes: siluridae), Locality: River Yamuna, Etawah, U.P., India.

Infection site: Gills.

Present host record, additional locality & collection dates: Host: Bagarius bagarius (Hamilton), Locality; River Sharda,

Lakhimpur Khiri, India (27°5′ 83–28°6′^N; 80°34′–81°30′E)

River Gomti, Lucknow, India (26°45′ 84–27°N;80°50′ 85–81°05′E)

Number of parasite specimens examined: 10

Specimens deposited: Voucher specimens W9370/1, W9376/1-W9378/1 in ZSI, Kolkata.

Redescription: Body length370 (350–380; n = 10); maximum width 120 (110–125; n = 10) at mid-length of body. Cephalic region well developed; four cephalic lobes. Two pairs of eye spots, posterior pair larger, accessory granules absent. Pharynx spherical, 22 (20–25; n = 10) in diameter; oesophagus short to non-existent.

Testis 30 (25–35; n = 8) long, 12 (10–14; n = 8) wide; vas deferens loops left intestinal caecum; two seminal vesicle, a sigmoid dilation of vas deferens, present. Two Prostatic reservoirs present. Copulatory complex consists of a copulatory tube, proximally articulating accessory piece. Copulatory tube sclerotised, 45(40–47; n = 10) long. Accessory piece, divided into two pieces, 60(55–65; n = 10) long. Ovary round to oval, long, intercaecal; oviduct, ootype, uterus not observed. Seminal receptacle, vaginal armament not observed. Vitellaria dense, throughout trunk, except in regions of reproductive organs.

Haptor 120 (110–125; n = 10) long, 140 (135–145; n = 10) wide. Dorsal anchor, inner length 60 (55–65; n = 10), recurved point 22 (20–25; n = 10) long, Patch 50 (46–54; n = 10), Ventral anchor: inner length 34 (30–36; n = 10), recurved point 22 (20–25; n = 10) long, outer and root having facets. Dorsal connective bar fenestrated 72.

(70–75; n = 10) long, Ventral bar, 57 (55–58; n = 10) long. Serrated onchium, 30(28–32; n = 10) long. Sclerite, 35 (32–36; n = 10) long. Seven pairs hooks. Three pairs with dilated proximal handles, others are of larval type with dimensions as follows-: pair 2, 6, 5 and 7 larval types: 10 long, pairs 1 and 4:50 long; pair 3:38 long.

Remarks: Bychowskyella bagariusi was described by Sharma (1983) from river Yamuna at Etawah, Uttar Pradesh from the gills of Bagarius bagarius. Lim et al. (2001) considered it as species inquirenda. Our collection and study of specimens from the type host, revealed it to be a valid species. In the present specimens, the outer and inner root of ventral anchor, having small facets has been recorded for the first time. The patches on dorsal anchors were wrongly designated as accessory bars. The intestinal caeca were confluent. Sharma (1983) recorded only six pairs of hooks instead of seven in the specimens. Serrations on onchium, a unique feature, was not recorded earlier in the species. Complicated structure of accessory piece of copulatory organ is also well illustrated in the present study.

Class Monogenoidea Bychowsky, 1937

Dactylogyridea Bychowsky, 1937

Dactylogyridae Bychowsky, 1933

Thaparocleidus Jain, 1952.

Thaparocleidus indicus (Kulkarni 1969) Lim, 1996.

Syn.: Bychowskyella singhi Rajeshwari and Kulkarni, 1983. (Figs. 9, 10–16).

Fig. 9.

Thaparocleidus indicus Kulkarni, 1969 (ventral view)

Figs. 10–16.

Thaparocleidus indicus (Kulkarni 1969) Lim, 1996. 10 Dorsal anchor. 11 Ventral anchor. 12 Dorsal bar. 13 Ventral bar. 14 Vagina. 15 Hooks. 16 Copulatory complex

Previous record and locality: Padhan, Wallago attu (Bloch & Schneider). (Siluriformes: Siluridae) from.

Hyderabad.

Infection site: Gills.

Present record and locality: W. attu (Bloch & Schneider), river Gomti, Lucknow, India (26°45′ 84–.

27°N;80°50′ 85–81°05′E).

Number of specimens examined: 15.

Specimens deposited: Voucher specimens W9371/1, W9379/1 & W9380/1 in ZSI, Kolkata.

Redescription: Body 1,000 (990–1010; n = 10) long; maximum width 120 (110–125; n = 10) at mid-length. Cephalic region well developed; four cephalic lobes. Two pairs of eye spots, posterior pair larger, accessory granules absent. Pharynx spherical, 22 (20–24; n = 10) in diameter; oesophagus short to non-existent. Testis 60 (58–62; n = 8) long, 45 (42–47; n = 8) wide; vas deferens loops left intestinal caecum; seminal vesicle a sigmoid dilation of vas deferens. Prostatic reservoir (s) not observed. Copulatory complex consists of a ‘spicule-like’ copulatory tube and proximally articulating ‘spicule- like’ accessory piece. Copulatory tube sclerotised, 58 (5560; n = 13) long. Accessory piece, 61 (58–62; n = 13) long. Ovary round to oval, long, intercaecal; oviduct, ootype, uterus not observed. Seminal receptacle not observed. Vaginal armament 35 (33–36; n = 5). Vitellaria dense, throughout trunk, except absent in regions of reproductive organs.

Haptor 75 (72–77; n = 10) long, 125 (122–127; n = 10) wide. Dorsal anchor: outer length 45 (43–46; n = 10) Dorsal anchor: inner length 35 (33–36; n = 10), recurved point 15 (13–16; n = 10) long, Patch 11 (8–13; n = 10), Ventral anchor: inner length 30 (26–33; n = 15), recurved point 14 (12–16; n = 10) long, Ventral anchor: outer length 40 (35–45; n = 10). Dorsal connective bar, transverse shaft like, lacking a fenestration, 43 (40–45; n = 14) long, Ventral bar, “V- shaped”, 25 (22–27; n = 13) long, Seven pairs of similar shape and size 14 (12–16; n = 10) hooks.

Remarks: Bychowskyella singhi was described by Rajeshwari and Kulkarni (1983) from the gills of W. attu at Hyderabad. Lim et al. (2001) considered it as species inquirenda. We have collected this species on the type host, from an additional locality and studied in detail. We compared our specimens with the original descriptions as the types were not available for study (not deposited by earlier workers). The present study revealed it to be a species of Thaparocleidus (as pointed out by Lim 2001) because the dorsal bar of B. singhi, lacked central fenestration (a generic feature of Bychowskyella); patches on dorsal anchors are long and recurved in Bychoskyella, while those of B. singhi are very small; 1st, 3rd and 4th hooks are with dilated proximal handles and 2nd, 6th, 5th and 7th are of larval type in Bychowskyella while in B. singhi, all hooks are of variable shapes and sizes (a character of the genus Thaparocleidus.) Present study has, therefore, revealed it to be Thaparocleidus indicus (Kulkarni 1969) Lim, 1996, owing to the ‘spicule-like’ copulatory complex, ‘V-shaped’ ventral bar, and ‘shaft-like’ dorsal connective bar.

Discussion

Misidentification and misinterpretation of monogenetic parasites often creates problems in their taxonomy leading to incorrect phylogenies. Owing to the confusion prevailing in India regarding these parasites, where types have almost never been, properly deposited or made available to taxonomists, problems like this needs to be focused upon. Thus, for correct evolutionary studies, proper identification and authenticity of these parasites is of utmost importance. Bychowskyella species possesses three pairs of large hooks and four pairs of small hooks and two additional rod-like sclerites one on either side of dorsal anchors (Lim et al. 2001). Genus Bychowskyella Achmerov, 1952 has 17 valid species as listed by Lim 2001 in India. Based on present study, B. bagariusi is valid and B. singhi Rajeshwari & Kulkarni 1983 belongs to the genus Thaparocleidus Jain 1952.