Molecular phylogenetics reveals a species complex pattern of closely related members of genus Thelohanellus (Cnidaria: Myxosporea) from the Indian subcontinent.

Out of the total 2600 myxozoan species reported so far, Thelohanellus Kudo, 1933 is the second most prevalent genus comprising of about 150 species after Myxobolus Butschli, 1882 infecting both freshwater and marine fishes. In general, these are mostly histozoic (within the tissues) and sometimes coelozoic (in body cavities). The present paper deals with the study of a novel Thelohanelloid T. neocyprini infecting gills of Catla catla and species complex among the member species of Thelohanellus genus from the Indian subcontinent infecting gills, fins and muscles. The species forming species complex are T. rohitae, T. catlae, T. jiroveci, T. seni, T. bifurcata, T. dykovae, T. neocyprini, T. filli, T. muscularis and T. theinensis. The phylogenetic analysis was also done on the basis of 18S rDNA. The homogeneity was found to be between 90 and 99%. The factors responsible for the species complex could be phylogeography, host reluctant, organ and tissue specificity of the these myxozoan parasites. Study of more genetic markers facilitated with morphotaxonomy can be used to sort out the occurrence of species complex among the morphologically different species having similar genetic makeup and vice-versa.

Species diversity of the genus Thelohanellus Kudo, 1933 (Myxozoa: Bivalvulida) parasitizing fishes in Indian subcontinent.

A synopsis of 52 nominal species of the genus Thelohanellus Kudo, 1933 reported to infect freshwater fishes in India is presented. These species infect various organs such as gills, fins, scales, skin, muscles, gall bladder, kidney etc. The diagnostic features of the genus include tear-shaped myxospores with smooth shell valves and single polar capsule. The members are histozoic in their nature of parasitism infecting fresh water fishes. The present manuscript is aimed to compile the list of reported species in India along with essential information on morphometrics of vegetative stage, host, organ preference and pathogenic effects if any. Maximum number of species are recorded from state of West Bengal (25) followed by 23 in Punjab (out of which 8 were already reported from other states of India), Andhra Pradesh (7), Orissa (3), Manipur (1) and Haryana (1). Majority of the species have been recorded to infect major and minor carps (43 species) and 9 species in cat fishes. Out of 43 species infecting Indian major carps, T. batae infected the epithelial lining of gill filament of Labeo bata and also the wall of the duodenum and pectoral fin of Wallago attu in Harike Wetland (Punjab). Organ distribution of the species belonging to the genus Thelohanellus indicated that the plasmodia of 27 species were located in the gills, 14 species in the fins, 7 species in the gall bladder, 4 species in muscles and 3 species in kidney, 2 each in scale and skin on the head region and 1 species each in brain, eye, spleen, liver and wall of the duodenum. Recent studies conducted by the authors and also by few earlier studies in West Bengal have documented many species of Thelohanellus to cause serious gill haemorrhagic disease and dermal lesions. Histological studies on the gills of cultured carps in Punjab infected with members of Thelohanellus have indicated that these parasites cause 15-20 % damage to respiratory surface leading to localized loss of function.

Molecular identification of a new myxozoan, Myxobolus dermiscalis n. sp. (Myxosporea) infecting scales of Labeo rohita Hamilton in Harike Wetland, Punjab (India).

In the present study, a new species Myxobolus dermiscalis n. sp. infecting scales of Labeo rohita, an Indian major carp from Harike Wetland in Punjab, India has been described on the basis of spore morphology and amplification of a part of 18S rDNA gene. The pseudocysts of M. dermiscalis n. sp. are milky white with irregular outline, 0.5-3.6 mm in diameter embedded within the dermal scale in the form of a cavity. The spores 5.84-7.98 × 3.98-5.98 µm in size, having two equal polar capsules 3.98-5.98 × 1.85-3.85 µm in size. The most differentiating feature from closely related species, Myxobolus saugati (Kaur and Singh, 2011) is the presence of two parietal folds at the posterior - lateral margins of the shell valves. The present species is regarded as host, organ and tissue specific in nature. The partial sequence of SSU gene of M. dermiscalis n. sp. clustered with other Myxobolus species infecting cyprinids available in the GenBank. Blast search revealed 98% homogeneity with Myxobolus sp (KM401439) infecting scales of L. rohita in Myanmar (unpubl. data). The present myxobolid parasite has been recorded to cause serious, highly symptomatic disease of the scales, causing their loosening from the skin of L. rohita. It rendered the host fish unsightly giving it cloudy appearance with white patches and mucoid body surface. Scale pseudocyst Index (SPI) has been provided to record the intensity of infection.

Morphological and molecular characterization of Henneguya bicaudi n. sp. (Myxosporea: Myxobolidae) infecting gills of Cirrhinus mrigala (Ham.) in Harike Wetland, Punjab (India).

In the present study, Henneguya bicaudi n. sp. infecting gills of Cirrhinus mrigala (Ham.) an Indian major carp from Harike Wetland in Punjab, India, has been described on the basis of myxospore morphology and partial amplification of the SSU rRNA gene. The pseudocysts of H. bicaudi n. sp. were located within the gill filament, whitish with round to irregular outer margin and 0.5-0.7 mm in diameter, 3-4 pseudocysts each containing about 50-100 myxospores were detected per gill. Mature myxospores were oblongate, 21.0 × 6.2 µm had a caudal appendage bifurcating into two thin thread-like branches starting posterior to middle of its length. The two equal polar capsules were 3.14 × 2.02 µm. The present species was compared morphologically with 21 species of the genus Henneguya infecting fresh water fishes in India and related geographical area. H. bicaudi n. sp. differed in having a peculiar oblongate shape and size of the myxospore, equal polar capsules, and also by the location of the point of bifurcation of the caudal appendage. 18S rDNA sequences of H. bicaudi n. sp. obtained revealed 96% homogeneity with H. pseudorhinogobi (Kageyama et al., Fish Sci 75:657-663, 2009) infecting gill filaments of Rhinogobius sp. (Rutter, PANS Philad 56-90, 1897) in Japan. The intensity of infection was determined by the gill pseudocyst index (GPI) based on the number of countable pseudocysts by stereo zoom trinocular microscopy per gill (on one side).

Morphological and Morphometrical Characterization of Meloidogyne incognita from Different Host Plants in Four Districts of Punjab, India.

The population of M. incognita, the root knot nematode (RKN) was found infesting five different host plants (okra, banana, sunflower, bottle gourd, and brinjal) out of 24 examined from four districts of Punjab, India (Gurdaspur, Ludhiana, Patiala, and Hoshiarpur). Morphological and morphometrical characterization indicated that in the case of mature female, the characters of body length and width, neck length, ratio 'a', anus to tail terminus (ATT), interphasmid distance (IPD), and perineal pattern were recorded as stable characters. These taxonomic characters can be reliable for identification. All characters of second-stage juvenile (J2) such as body length, stylet length, head to median bulb length (H-MB), distance from median bulb to excretory pore (MB-EP), tail length, anal body width (ABW), and ratios C and C' were highly variable. Analysis of interpopulation morphometric characters of mature female of M. incognita, namely, body length, width, and ratio 'a' were moderately variable characters (CV 0.26% to 20%) and stylet length, neck length, length of median bulb (LMB), and width of median bulb (WMB) were highly variable (CV 1.0% to 36.1%). In the perineal pattern, the two characters ATT and IPD were moderately variable (CV 8.8% to 17.6%) and two characters, anus to vulval slit (AVS) and length of vulval slit (LVS), were highly variable (CV 2.1% to 40.5%). In J2, body length, stylet length, H-MB, MB-EP, ABW, tail length, ratios C, and C' were highly variable characters (CV > 12%).