Danio annulosus
| Danio annulosus | ||||||||||||
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| Scientific name | ||||||||||||
| Danio annulosus | ||||||||||||
| Kullander , Rahman , Norén & Mollah , 2015 |
Danio annulosus is one of only a location on Kaptai Dam in Bangladesh known rasbora the genus Danio . The species was only described in 2015.
description
The types have a standard length between 50 and 72 millimeters for females and between 41 and 51 millimeters for males, with a head length of 21 to 24 millimeters. Apart from that, no sexual dimorphism can be seen . The body is elongated, the head slightly flattened and about as wide as it is high. The snout is short and rounded, the length corresponds to an eye diameter. The mouth is terminal and it has a slightly protruding lower jaw. The nasal barbs hardly extend beyond the fore- lid , at most to the middle of the gill-lid . The chin barbels are significantly longer, they reach to the base of the pectoral fins or a little further.
The first rays of the pectoral fins are only slightly elongated and undivided, the first ray of the pectoral fin is not elongated. Above the pectoral fins there is a pronounced black shoulder mark of a slightly oval shape, behind it an orange-colored mark that fades after some time in preserved specimens. The drawing is dominated by a double row of lateral dark rings, which extend with small spaces from the rear edge of the gill cover along the body and the lower one does not merge with the caudal peduncle. In living specimens, the lines are dark blue and their surroundings and the interior of the rings are colored orange. In the sideline row there are 34 or 35 scales, while in Danio sysphigmatus there are 35 to 38 scales. The pectoral fins do not extend beyond the roots of the pelvic fins and the pelvic fins do not reach the anus.
6.5 / 34-35 / 1; 1.5 / 14
Dorsal II / 9½-11½; Anal III / 13½-15½; Pectorals I / 12-13; Ventral I / 7
Danio annulosus belongs to the group of species of the genus Danio, informally known as chain danios . What they have in common, which gives them their name, is a noticeable row of dark rings on the side, separated by small spaces. Further correspondences are the complete sideline , the elongated first ray of the pectoral and pelvic fins, the black shoulder patch over the pectoral fins, the 14 scales around the caudal fin stalk and the standard length of 60 to 88 millimeters. With the combination of these characteristics, the chain danios differ from the other species of the genus, which never have all of the characteristics mentioned. Danio annulosus differs from all other chain danios by the significantly shorter pectoral and pelvic fins and the slightly elongated or transversely oval shoulder patch.
The species is particularly similar to the two species Danio catenatus and Danio concatenatus , which originate from western Myanmar , but differs from them in details of the drawing, the shorter pectoral fins and the mitochondrial DNA .
distribution
The terra typica and the only known site of Danio annulosus is a basin at the foot of the waterfalls at Shuvolong or Shublong, about 11 kilometers from Rangamati in the province of Chittagong Hill Tracts ( 22 ° 42 ′ 41.4 ″ N , 92 ° 15 ′ 35 " O ). There are several waterfalls in the area, the highest of which has a height of about 100 meters and at the foot of which is the site of Danio annulosus . In the rainy season, the water falls directly into the Karnaphulistausee . In the dry season only a thin trickle runs over the rocks and feeds a 40 centimeter deep pool on a rock terrace, which is flooded in the rainy season by the higher water level of the reservoir. The entire series of Danio annulosus types, together with shrimps , snails and small fish of the likewise new species, Garra mini, were caught in this pond, which runs into the lake through a drainage less than one centimeter deep and has no vegetation . The fish species Esomus danricus , Rasbora daniconius , Dermogenys burmanica , Aplocheilus panchax and Trichogaster lalius , which are common in Bangladesh , were caught in the lake directly at the outflow of the pond . Shuvolong can be reached from Rangamati by motorboat and has become a tourist destination because of the impressive waterfalls and the Shuvolong market.
It is considered unlikely that danio annulosus originated from the upper water system that feeds the falls. The fish are likely to be lured there by the inflow of fresh water when the water level is high, when the lake is flooded, and they are cut off from the lake when the water level drops during the dry season. In extreme drought, the pond is likely to fall completely dry, which means that permanent colonization by the two fish species found there is excluded. It is unclear whether these are surviving remnants of a population whose flowing waters were destroyed by the damming of the Karnaphulistausee in the 1960s, or whether these are animals from other tributaries of the lake that came to their place of capture during the rainy season.
Although Danio annulosus was only found in one place, it is assumed that the species will spread further in the catchment area of the Karnaphuli . The Chittagong Hill Tracts Province is located on the western edge of a region known for its great biodiversity , stretching from eastern Bangladesh through neighboring Myanmar to southern China, the foot of the Himalayas and most of Thailand. The Bengali fish fauna of this region and the lowlands around the Ganges-Brahmaputra Delta seem to be clearly different and Danio annulosus belongs to the fauna of eastern Bangladesh and Myanmar.
Shuvolong Falls in summer
Water flow in winter
Drain from the terrace
Shuvolong Falls as a tourist destination
Hazard and protection
In view of the lack of information about possible further sites and the frequency of the species at the known site, a classification was dispensed with for the Red List of Endangered Species of Bangladesh in 2015 and reference was made to the insufficient data basis (category DD - Data Deficient ).
Systematics
In 2015, the Swedish ichthyologist Sven O. Kullander described four species within the genus Danio , Danio assamila , Danio catenatus , Danio concatenatus and Danio sysphigmatus , which, because of their characteristic lateral markings with the long-known Danio dangila, belong to the informal group of chain danios ( German: Ketten-Danios ) summarized. Danio annulosus also belongs to this group .
The informal group of chain danios forms a clade within the monophyletic genus Danio . Within this group, Danio annulosus is the sister taxon of Danio catenatus , next to these two is the sister group Danio concatenatus and Danio sysphigmatus .
The holotype is probably a female specimen and is in the collection of the University of Dhaka with four probably male paratypes . Four probably female and one male paratype have been added to the collection of the Natural History Museum in London.
The specific epithet annulosus is derived from the Latin noun annulus (German: ring ). It refers to the dark circles arranged laterally in the longitudinal direction.
literature
- Sven O. Kullander et al .: Danio annulosus, a new species of chain Danio from the Shuvolong Falls in Bangladesh (Teleostei: Cyprinidae: Danioninae) . In: Zootaxa 2015, Volume 3994, No. 1, pp. 53-68, doi : 10.11646 / zootaxa.3994.1.2 (first description).
Web links
- Danio annulosus on Fishbase.org (English)
Individual evidence
- ↑ a b Sven O. Kullander et al .: Danio annulosus, a new species of chain Danio , pp. 56-58.
- ↑ a b Sven O. Kullander et al .: Danio annulosus, a new species of chain Danio , pp. 53-54.
- ↑ Sven O. Kullander: Taxonomy of chain Danio, an Indo-Myanmar species assemblage, with descriptions of four new species (Teleostei: Cyprinidae) . In: Ichthyological Exploration of Freshwaters 2015, Volume 25, No. 4, pp. 357-380, digitized .
- ↑ a b Sven O. Kullander et al .: Danio annulosus, a new species of chain Danio , p. 58.
- ↑ Md. Mizanur Rahman et al .: Garra mini, a new small species of rheophilic cyprinid fish (Teleostei: Cyprinidae) from southeastern hilly areas of Bangladesh . In: Ichthyological Exploration of Freshwaters 2016, Volume 27, No. 2, pp. 173-181, digitized .
- ↑ a b Sven O. Kullander et al .: Danio annulosus, a new species of chain Danio , p. 66.
- ↑ Abu Tweb Abu Ahmed, Mohammed Mizanur Rahman and Suman Mandal: Biodiversity of hillstream fishes in Bangladesh . In: Zootaxa 2013, Volume 3700, No. 2, pp. 283-292, doi : 10.11646 / zootaxa.3700.2.6 .
- ↑ Md. Mizanur Rahman et al .: Danio annulosus . In: IUCN Bangladesh (ed.): Red List of Bangladesh. Volume 5. Freshwater Fishes . International Union for Conservation of Nature (IUCN), Bangladesh Country Office, Dhaka 2015, p. 294.
- ^ Sven O. Kullander et al .: Danio annulosus, a new species of chain Danio , p. 60.