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Some like it hot: A new freshwater crustacean from the hottest place on earth

Dr. Hossein Rajaei, curator of the Lepidoptera collection.

The Lut desert – also known as Dasht-e Lut – located in south-eastern Iran between between the 33rd and 28th parallels. With 51,800 km2, this secons largest Iranian desert is larger than Switzerland. This desert holds the current record for the highest ever recorded surface temperature: based on 2006 satellite measurements, NASA reported a record surface temperature of 70.7 °C, which more recently has been increased to even 80.8 °C. Dark pebbles that heat up are one of the causes of these record temperatures. Mean daily temperatures range from -2.6 °C in winter to 50.4 °C in summer, with annual precipitation not exceeding 30 mm per year.

Desert Lut in Iran (Picture: H. Rajaei).

Three interdisciplinary scientific expeditions were undertaken in this extreme habitat from 2015 to 2017. The aim: to better understand the ecology, biodiversity, geomorphology and paleontology of this hotspot. In two of these expeditions I was on board, and have reported earlier about the 2016 expedition here in Science Blog (in German). In fact I am a lepidopterist and these insects are of course at the heart of my scientific interest. However, as a biologist I’m interested also in other living organisms. In an expedition to an extreme habitat like Lut Desert, all sensors will be on, especially when one is faced with water!

Habitat of the new species Phallocryptus fahimii in the desert Lut (Picture: H. Rajaei).

Water bodies in the desert are scarce goods. Except a permanent extremely salty river (Rud-e Shur) there are no permanent water bodies in the Lut desert. However, sometimes, heavy seasonal rains form several small ponds. Although a diverse community of Archaea has been described from Rud-e Shur, aquatic life in the Lut remains highly limited. Therefore, when we saw one of these temporary ponds in the south of the desert, it magically attracted my attention, and I could observe a Crustacean species! I collected some of them for scientific proof.

New species Phallocryptus fahimii discovered from desert Lut, the hottest place on planet Earth
(Picture: M. Pallmann).

These are also known as fairy shrimps (Branchiopoda: Anostraca) and reproduce via “resting eggs”. These eggs show exceptional resistance and are able to survive for decades in the dry desert floor. They will hatch during the next wet season, when the aquatic habitat refills. Thus, these animals are perfectly adapted to live in such an extreme environment. Like many diverse groups of animals, one needs specialists for a confident identification. Therefore I contacted Crustacea specialist Dr. Martin Schwentner from the Natural History Museum of Vienna. And as I had guessed already, my cructacean was new, and more specifically an undescribed species from the genus Phallocryptus! There are only four known species in this genus from different arid and semiarid regions.

Hadi Fahimi (Picture: B. Izadi).

The new species was published together with Martin Schwentner und Alexander V. Rudov under the name Phallocryptus fahimii in the scientific journal “Zoology in the Middle East”. Phallocryptus fahimii differs in its overall morphology and its genetics from all other known Phallocryptus species. It was named in honor of the Iranian conservation biologist, Hadi Fahimi, who took part in the 2017 expedition in desert Lut and who we tragically lost in an airplane crash on 18 February 2018.


References

Schwentner, M., Rudov, A. V. & Rajaei, H. 2020. Some like it hot: Phallocryptus fahimii n.sp. (Crustacean: Branchiopoda: Anostraca: Thamnocephalidae) from the hottest place on planet Earth. Zoology in the Middle East,DOI: https://doi.org/10.1080/09397140.2020.1805139

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