Zoology


https://sites.google.com/a/gauhati.ac.in/research/#ds11092019 A new fish species from Kameng river stream

https://sites.google.com/a/gauhati.ac.in/research/#ds11092019 A new fish species from Diyung river (Assam)

https://sites.google.com/a/gauhati.ac.in/research/#ds11092019 Ovicidal agents for Aedes aegypti

https://sites.google.com/a/gauhati.ac.in/research/#ds11092019 Antibacterial activity of Spotted Gum

https://sites.google.com/a/gauhati.ac.in/research/#ds11092019 A new species of stone loach

https://sites.google.com/a/gauhati.ac.in/research/#ds11092019 Key lime oils on Aedes aegypti

https://sites.google.com/a/gauhati.ac.in/research/zoology/#rdc30082019 Embryonic development of pipefish

https://sites.google.com/a/gauhati.ac.in/research/zoology/#bk01072019 Killing the killers

https://sites.google.com/a/gauhati.ac.in/research/zoology/#hc01022019 Schistura rebuw - a new species of fish

A new fish species - Psilorhynchus kamengensis

Dandadhar Sarma and co-workers report about a new fish species from a stream of Kameng river, a northern tributary of the Brahmaputra drainage system in the northeastern state of Arunachal Pradesh, India. This work is published in the Vertebrate Zoology. They have reported another new species of the same genus, a few weeks ago (see the Highlight, immediately below).


Authors
Abhinit Dey, Hrishikesh Choudhury, Abhishek Mazumdar, Ratul Ch Bharali1, Sarbojit Thaosen1, and Dandadhar Sarma
from other institutions

Abstract
Psilorhynchus kamengensis, new species, is described from a stream of the Kameng River, a northern tributary to the Brahmaputra drainage, Arunachal Pradesh, northeast India. The new species belongs to the P. balitora species group and can be distinguished from all other members of this group by the presence of a longer post-epiphyseal fontanelle, 3 unbranched anal-fin rays, 9 + 8 caudal-fin rays, 35 vertebrae and fin coloration. The validity of the species is also corroborated by molecular phylogenetic analysis based on the mitochondrial cyt b gene.

Journal Reference
https://sites.google.com/a/gauhati.ac.in/research/zoology/#top 
 



A new fish species - Psilorhynchus nahlongthai

Dandadhar Sarma and co-workers report about a new psilorhynchid fish from Diyung river, a tributary of Kopili river in the northeastern state of Assam, India. This work is published in the Journal of Fish Biology.


Authors
Abhinit Dey, Hrishikesh Choudhury, Sarbojit Thaosen1, and Dandadhar Sarma
from other institution

Abstract
Psilorhynchus nahlongthai, a new psilorhynchid fish, is described from the Diyung River, a tributary to the Kopili River (itself a southern tributary of the Brahmaputra drainage) in Assam, northeast India. It is placed in the Psilorhynchus balitora species group and can be easily distinguished from all other members of this group by a com- bination of the following characters: dense and prominent tuberculation on the head region; thick and long pre- and post-epiphyseal fontanelles on the neurocranium; 9 +8 caudal-fin rays; and 34 (24+10) vertebrae. Genetic divergence between P. nahlongthai and members of the P. balitora species group from the Brahmaputra and neighbouring drainages, with K2P distances ranging 3.7%–14.7% and 7.4%– 20.7% in the mitochondrial COI and cyt b gene datasets respectively, support its report as a new species.

Journal Reference
https://sites.google.com/a/gauhati.ac.in/research/zoology/#top 
 



Essential oils as ovicidal agents for Aedes aegypti (Diptera: Culicidae)

Bulbuli Khanikor and coworkers study the twenty essential plant oils (EO) as potential ovicidal agents for the mosquito species which can spread diseases like dengue fever, chikungunya, Zika, and several others. This work is published in the journal National Academy Science Letters.


Authors
Riju Sarma, Kamal Adhikari, Sudarshana Mahanta, and Bulbuli Khanikor

Abstract
In the present investigation, twenty plant essential oils (EOs) are tested against Aedes aegypti at their egg stage aiming to control the mosquito population at its breeding site. The results are very much promising for EOs extracted from Allium sativum, Mentha piperita and Ocimum sanctum with sublethal concentration (LC50) of 1.00 ppm, 4.01 ppm and 8.40 ppm, respectively, which seems to be at par with WHO-recommended dose for synthetic larvicide temephos. Three plant oils responded with LC50 below 50 ppm. However, few plant oils did not show lethal effects at all. The effective EOs can in future be used in breeding sites including the potable and household water tank as these plants are edible and hence safe for consumption. These might be a potent candidate for decreasing Aedes population and for replacing synthetic insecticides against Aedes. Moreover, these three highly effective EOs would be accessible and cost-effective for common people to use.

Journal Reference
Botany    https://sites.google.com/a/gauhati.ac.in/research/#top 
 



Antibacterial activity of Spotted Gum (Eucalyptus maculata Hook.) against fish pathogens

Dandadhar Sarma and co-workers investigate the antibacterial properties of leaf essential oil of Sotted Gum against two fish pathogens. This work is published in Journal of Essential Oil Bearing Plants.


Authors
Abhishek Mazumder, Hrishikesh Choudhury, Abhinit Dey, and Dandadhar Sarma

Abstract
The present study was intended to evaluate the antibacterial activity of leaf essential oil (EO) of E. maculata and its major compound, identified from the crude EO against Aeromonas hydrophila and A. jandaei. The major compound was found to be 1,8-cineole through Gas Chromatography-Mass Spectrophotometry-Flame Ionisation Detector analysis. Both EO and 1,8-cineole showed potential antibacterial activity against the tested microorganisms. Sensitivity of A. hydrophila to both crude EO and its major compound was found to be relatively higher, in comparison to A. jandaei. The positive results indicate their efficiency as a natural anti-bacterial agent for the treatment of several pathogenic diseases caused by these two microorganisms, and understanding the relations between traditional cures and current medicines.

Botany    https://sites.google.com/a/gauhati.ac.in/research/zoology/#top 
 



Schistura syngkai - a new species of stone loach

Hrishikesh Choudhury and coworkers report about the discovery of a new fish species of stone loach from Meghalaya. This discovery is published in the journal Zootaxa.


Authors
Hrishikesh Choudhury, D Khlur B Mukhim1, Abhinit Dey, Deisakee P Warbah1, and Dandadhar Sarma
from other institution

Abstract
Schistura syngkai, a new stone loach, is described from the Twahdidoh Stream of Wahblei River (Surma-Meghna drainage) in Meghalaya, northeast India. It is unique among its Indian congeners in having a prominent dark-brown to blackish mid- lateral stripe about an eye diameter or more in width, overlain on 12–18 vertically-elongate black blotches on a golden-brown to amber body. Additionally, the species possesses an incomplete lateral line and a slightly emarginate caudal fin, and exhibits no apparent sexual dimorphism.

Journal References
https://sites.google.com/a/gauhati.ac.in/research/zoology#top 
 



Key lime oils on Aedes aegypti

Bulbuli Khanikor and co-workers report about the insecticidal activities of Key lime (Assamese : Sokola Tenga) oils on Aedes aegypti, the mosquito that causes dengue fever. This work is published in the journal Toxicology Reports.


Authors
Riju Sarma, Kamal Adhikari, Sudarshana Mahanta, and Bulbuli Khanikor

Abstract
In the recent time, global attention for the control of vectors has shifted from chemical insecticides to botanicals. In the present investigation, authors attempted to evaluate the efficacy of peel and leaf essential oil (EO) of Citrus aurantifolia (Assamese : Sokola Tenga) against Aedes aegypti. The results revealed that both the oils possess more ovicidal activity (LC50 value of 5.26 ppm and 17.71 ppm for leaf and peel oil respectively at 72 h) than larvicidal activity. As larvicide, the essential oil from the peel of Citrus aurantifolia showed rapid effect with LC50 value of 128.81 ppm at 24 h which reduced to 106.77 ppm at 72 h while the leaf oil showed slow effect with LC50 value of 188.59 ppm, 107.37 ppm and 104.59 ppm at 24 h, 48 h and 72 h respectively. Again, the two essential oils did not show significant adulticidal activity. GC–MS analysis of both the oils recorded presence of different compounds. As a major constituent compound of the leaf EO of Citrus aurantifolia, citral was tested for their ovicidal, larvicidal and adulticidal activities against Aedes aegypti. The result showed highest ovicidal activities (LC50 value of 4.84 ppm at 72 h) of citral followed by larvicidal (LC50 value of 87.02 ppm at 24 h) and adulticidal (LC50 value of 103.88 ppm at 24 h) activities. From this study, it can be concluded that the essential oil extracted from the leaf and peel of Citrus aurantifolia and one of its major constituent compound citral can be included in the mosquito control programme of Aedes aegypti.

Journal References
https://sites.google.com/a/gauhati.ac.in/research/zoology/#top 
 



Embryonic development of a pipefish

Dandadhar Sarma and collaborators report about a first comprehensive embryonic development of an endangered freshwater pipefish endemic to the region, which may help conserve such species. This work is published in the Journal of Applied Ichthyology.



Authors
Anu Saikia, Minakshi Kalita, Hrishikesh Choudhury, Lalit K Tyagi1, Dandadhar Sarma, and Kuldeep K Lal1
from other institutions

Abstract
The present study provides the first comprehensive embryonic development of the freshwater Syngnathid fish species, Microphis deocata (Hamilton), a Near Threatened pipefish endemic to the Brahmaputra River drainage in Northeast India and Bangladesh. Microphis deocata is a Gastrophori species as the males develop an abdominal brood pouch. Mature individuals were collected and maintained in well‐aerated aquaria under controlled conditions to induce natural spawning. The number of eggs within the males' brood pouch ranged from 17 to 22 (for n = 10), measuring 0.7–1.0 mm in diameter. A total of 10 developmental stages could be recognised under four developmental periods namely, early embryogenesis, eye development, snout formation and juvenile. However, sensitivity, and therefore mortality, while handling of this species restricted the study from reporting the exact time intervals for stages following the blastodisc formation ~48 hr post fertilisation. A newborn larvae measures ~14 mm and is free‐swimming with distinct dorsal fin (with 31–32 rays) and a sector‐shaped caudal fin (with 8–9 rays). The study aims to provide baseline information on the embryology of M. deocata in culture condition which will be helpful for future studies on conservation biology, population status and management of this species.

Journal Reference
https://sites.google.com/a/gauhati.ac.in/research/zoology/#top 
 



A concoction of oils for the killer mosquitoes 

Bulbuli Khanikor and her scholars test a concoction of plant-based oils to target the Aedes aegypti mosquitoes, which is the primary cause of diseases like dengue fever, chikungunya, etc. This research work is published in Nature Scientific Reports.


Authors
Riju Sarma, Kamal Adhikari, Sudarshana Mahanta, and Bulbuli Khanikor

Abstract
Twenty-eight combinations of plant essential oil-based terpene compounds were prepared and tested against larval and adult stages of Aedes aegypti. Initially five plant essential oils (EOs) were assessed for their larvicidal and adulticidal efficacy and two of their major compounds from each EO were identified from GC-MS results. Identified major compounds namely Diallyldisulfide, Diallyltrisulfide, Carvone, Limonene, Eugenol, Methyl Eugenol, Eucalyptol, Eudesmol and α-pinene were purchased and tested individually against Aedes aegypti. Binary combinations of these compounds were then prepared using sub-lethal doses, tested and their synergistic and antagonistic effects were determined. The best larvicidal compositions and the best adulticidal composition of terpene compounds and terpene plus commercial mosquitocidal compounds were highlighted based on small scale and large scale treatments on Aedes aegypti.

Schistura rebuw - a new species of stone loach

Hrishikesh Choudhury and his colleagues have reported the finding of a new fish species from the Kameng River of lower Arunachal Pradesh. This finding is published in the journal Zootaxa


Authors
Hrishikesh Choudhury, Abhinit Dey, Ratul Ch Bharali1, Dandadhar Sarma, and Waikhom Vishwanath1
1 from other institutions

Abstract
Schistura rebuw, new species, is described from the Kameng River, a north-bank tributary of the Brahmaputra, Arunachal Pradesh, India. The new species is easily distinguished from all known congeners in the Brahmaputra basin by its unique sexual dimorphism, specifically a suborbital slit in adult females, and a suborbital flap in adult males; and a colour pattern of 10–11 blackish bars on a greyish-beige body, the pre-dorsal bars mostly broken or incomplete, coalescing dorsally in a more or less alternate fashion.

Journal Reference
https://sites.google.com/a/gauhati.ac.in/research/zoology/#top