Lernaeid Copepod Parasitic on the Freshwater Fishes of Godavari River, Rajahmundry, Andhra Pradesh, India with Description of a New Species, Lernaea notopteri n.sp. from Notopterus notopterus

This work was carried out in collaboration between all authors. Author APV designed the study, collected the host samples from sampling sites, carried out dissections, collected the parasites and managed the literature searches. Authors MG and VC helped in processing the parasites and preparing the first and final draft of the manuscript. All authors read and approved the final ABSTRACT Lernaeid copepods are one of the most detrimental and ubiquitous ectoparasites of cultured and wild variety freshwater fishes. River Godavari offers a dynamic habitat to a wide variety of fishes which are in turn infected by endo and ectoparasites. In a copepod parasitic survey on various species of freshwater fishes of River Godavari, Rajahmundry from 2007-2009, a total of 5 freshwater fishes were parasitized by copepods of the genus Lernaea . Four different adult species of Lernaea were found clinging to the skin of Channa punctatus , Catla catla , Barbus sp. , Macrognathus aculeatus and Notopterus notopterus i.e., Lernaea bengalensis Gnanamuthu, [17], Lernaea cyprinacea Linnaeus, 1758, Lernaea cyprinacea mastacembeli Hu, [13] and a new species, Lernaea notopteri n.sp. The new lerneaid copepod, Lernaea notopteri was reported from Notopterus notopterus showed variations in cephalic arms, antenna, maxillipede and Leg-V from the other closely related species and hence was designated as new species.


INTRODUCTION
Ectoparasites in particular, lernaeids are deemed to be one of the most harmful and prevalent ectoparasites of cultured fishes [1]. Lernaeids commonly known as 'anchor worms' are the crustacean copepod parasites infecting a wide variety of wild caught and pond-raised freshwater fishes. Approximately, 110 lernaeid species have been reported under the genus [2]. Damage caused by Lerneids is very severe and can result in "Lernaeosis" outbreak infecting major parts of the body such as skin, eyes, gills, fins, mouth and tissues of infected fishes and results in the mortality of the young fishes [3][4][5][6]. Female lernaeids are known to be more parasitic in nature as they attack body surface of fish and penetrates deep into the tissues after eating fish scales forming a deep wounds which in turn invite secondary microbial infections [7][8][9][10][11][12]. Many scientists all over world focused on the severity, pathogenicity and diversity of lernaeid parasites infesting various freshwater fishes [2,3,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Also, few scientists added a note on the lifehistory of lernaeid parasites [15, [33][34][35]. River Godavari is known for its dynamic environment, enriched by the nutrients proved to be a highly productive and prospective field to accomplish fishery research. Godavari River inhabits a diversified array of teleostean fauna which in turn offer a diversified range of habitat to the metazoan parasitic fauna. This study aims to analyse the lernaeid copepods keeping the severity of the infection in view caused by these parasites on the freshwater fishes of River Godavari, Rajahmundry.

MATERIALS AND METHODS
Fish were collected from fishery locations and local markets near River Godavari, Rajahmundry, Andhra Pradesh during [2007][2008][2009] and were brought to the laboratory for thorough examination of skin and gills. The skin and gill filaments were carefully washed and teased, and the contents were observed under a stereo microscope (LM-52-3621 Elegant). Standard protocols were followed to preserve and identify the parasites [36,37]. Copepod parasites were collected and fixed in 10% formalin. The parasites were identified by keeping them in cavity blocks with a few drops of lactic acid for 12-24 hrs for clearing. Parasites were observed, identified and captured in photographs under Lynx trinocular microscope (N-800M). For detailed study, one parasite from each group was dissected; mouthparts and appendages were separated to draw line diagrams with the aid of attached drawing tube in the microscope. Measurements are given in millimetres (mm) with ocular micrometer unless otherwise stated.

RESULTS
In the present survey, only 5 freshwater fish were infected with the copepods of the genus Lernaea.  with numerous setae scattered on the outer margin; third segment with one seta on the inner distal margin; distal with one seta on the outer margin, three setae on the inner margin and a tuft of setae apically. Second antenna: Threesegmented; basal and second segment naked, distal long and slender terminally curved to a blunt spine with three setae on the inner margin and few setae apically. Maxillule: First maxilla not clearly visible. Maxilla: 2-segmented; basal stout and broader with a blunt conical process on the inner medial margin; distal narrow, short and curved to two stout claws. Maxilliped: Maxillipeds directed forwards close to other mouth appendages. It is short, with five terminal claws on the distal segment. Basal broad with a blunt conical process on the inner distal margin and a conical process with a spine on the inner proximal region. Legs I to IV biramous; with three-segmented exopod and endopod. Of the five pairs of thoracic legs, the first pair occurs on the first thoracic segment fused with head, while the remaining four are spaced on the neck and trunk. Coxapod with setae on either side. Leg-V: Uniramous, with one long and three short setae apically.

DISCUSSION
Lernaea is the widely distributed parasitic genus of the freshwater fishes. The genus Lernaea was first erected with L. cyprinacea Linnaeus, 1758 the type-species [38]. Later, the first Asiatic species L. elegans was reported from Anguilla Anguilla [39]. But this species was later considered as junior synonym of L. cyprinacea [40]. Ho (1998) 41]. This species was later described as L. elegans by Leighsharpe [39] which was considered as junior synonym of L. cyprinacea by Harding [40]. L. cyprinacea is not a host-specific and has a wide host range [10,18,21,[42][43][44][45][46][47][48][49][50][51]. According to Kabata [21], this species has been recorded from over 100 fish species from 25 families and 10 orders. Nagasawa et al. [51] recorded this species from 34 species and sub-species of fishes from 17 families and 10 orders and 2 amphibians of 2 families and 2 orders. In the present survey, these parasites were collected from Catla catla and Barbus sp. and hence were considered as L. cyprinacea.
The third lernaeid copepod identified in Macrognathus aculeatus was L. cyprinacea mastacembeli which was first proposed by Hu [13] from the gills of Mastacembelus aculeatus. It was considered as valid sub-species of L. cyprinacea [52]. In the present study, a large number of copepodid stages-I and IV of this species were obtained from Mastacembelus armatus and only single adult species was obtained from Macrognathus aculeatus and hence they were redescribed as L. cyprinacea mastacembeli Hu, [13].
In this study, the fourth species described was reported for the first time from the fish Notopterus notopterus. L.cruciata was described from Notopterus kapirat from River Godavari, Nanded but it differs from the present material in shape of cephalic arms [53]. [24] which shows few resemblances and differences with these parasites. Ho [2] gave a detailed cladistic analysis on Lernaeaidae from 8 families of the total 13 families of fish hosts examined. However, he didn't encounter any speices of Lernaea from notopterid fish. The present material resembles L. bengalensis in the leg armature, body size and shape but differ in the cephalic arms, presence of unisegmented fifth leg and first antenna. Cephalic arms are short, equal and simple in present parasites while they are unequal, long and unlobed in L. bengalensis. Leg-V is unisegmented with three short setae and a long seta terminally while it is vestigial in L. bengalensis. First antenna of our specimens is provided by 24 spine like setae while setation is reduced in L.
bengalensis. These parasites resemble L. chackoensis in leg armature but differ on the branching of cephalic arms, setation on first antenna, number of claws on maxilliped and fifth leg. Fifth leg is vestigial in L. chackoensis while it is unisegmented with 3 short setae and a long seta terminally in the present parasites. Maxilliped possesses 7 terminal claws in L. chackoensis while they are 5 in the present parasites. Present specimens resemble L. hersaragattensis in the setation on first antenna and leg armature but differ in their body shape, osphronemi in possessing a small cephalic arms, but differs in having 4-segmented first antenna, maxilliped with 5 terminal claws and absence of sixth leg as single setae. Present parasites characteristically differ from all these parasites in the shape of body, cephalic arms, first antenna and number of terminal claws in maxillipeds. A table comparing these parasites with related species is given in Table 6. In view of the above differentiating characters and the occurrence of the parasites in Notopterus notopterus, it is justified to erect it to the status of a new species and is named as Lernaea notopteri taking the name of the host into consideration.