Research Article |
Corresponding author: Valiallah Khalaji-Pirbalouty ( vkhalaji@sci.sku.ac.ir ) Academic editor: Saskia Brix
© 2024 Valiallah Khalaji-Pirbalouty, Manal Abdulrahman Al-Kandari.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Khalaji-Pirbalouty V, Al-Kandari MA (2024) The first report of two new janiroid isopod species (Asellota, Janiroidea) from the western Indian Ocean. ZooKeys 1219: 233-248. https://doi.org/10.3897/zookeys.1219.130895
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Two new janiroid isopod species, Heterosignum behbehanii sp. nov. and Uromunna alyamanii sp. nov., are described from the Kuwaiti waters, representing the first record of the genera in the western Indian Ocean. Heterosignum behbehanii sp. nov. is distinguished from its congeners by pereonites 2–7 with a pair of short single lateral spine-like processes; the relatively short length of the anterior part of its pleotelson, which accounts for about 0.1 of the total length of the pleotelson; and the stylet with an elongate, downwardly curved, and distally pointed apex. Uromunna alyamanii sp. nov. is equally unique, with the pleotelson bearing two denticles on each lateral margin, pleopod 2 endopod stylet extending beyond the apex of the protopod, and pleopod 4 exopod distal tip with a long plumose seta. This discovery of unique characteristics of the new species significantly enhances our understanding of marine biodiversity in the western Indian Ocean and underscores the importance of further research in this area. The identification keys are provided to all known species of Heterosignum and Indian Ocean Uromunna species.
Heterosignum, identification key, Indian Ocean, Kuwait, Munnidae, new record, new species, Paramunnidae, taxonomy, Uromunna
The superfamily Janiroidea Sars, 1897 is composed of 25 families, with Paramunnidae Vanhöffen, 1914 and Munnidae Sars, 1897, standing out as the two largest and most diverse families within the suborder Asellota (
The family Munnidae Sars, 1897, with its 114 described species distributed across six genera (
To date, 15 Uromunna species have been reported from the Atlantic Ocean, primarily in the northern regions, and 10 species in the Pacific Ocean. Notably, the eastern Indian Ocean, particularly the Australian region, is home to three Uromunna species: U. brevicornis (Thomson, 1946) from Swan River, Western Australia; U. humei Poore, 1984 from Apollo Bay, Victoria, and U. phillipi Poore, 1984 from Port Phillip Bay, Victoria. However, no Uromunna species have been reported from the western, northern, and southern regions of the Indian Ocean. This absence makes our discovery of two new species, one each from Heterosignum and Uromunna in the western Indian Ocean, particularly significant.
Sample collection was conducted during sampling trips (2013–2017), focusing on the littoral zone along Kuwait’s coastline and offshore islands (
The specimens’ sorting, dissection and imaging were performed using a Leica® M125 stereomicroscope equipped with a DFC450 camera. Dissected appendages were mounted onto glass slides in stained antibacterial glycerine-gelatine (Merck). Pencil appendage drawings were made using a Leica (DM1000) compound microscope equipped with camera lucida. All illustrations were electronically inked with Corel Draw (version X6). The specimens were prepared for SEM photographs using previously described techniques (
The morphological terminology used herein is a comprehensive compilation from established sources such as
Suborder Asellota Latreille, 1802
Superfamily Janiroidea Sars, 1897
Family Paramunnidae Vanhöffen, 1914
Heterosignum mutsuensis Gamô, 1976 (original designation).
The most recent revision and diagnosis of the genus is that of
The species is named in honour of Dr Abdulmanaf Behbehani, a respected figure who taught Marine Biology and Ecology at Kuwait University and researched Kuwait's marine environment and Kuwait's intertidal macrofauna for over four decades.
Holotype : • ♂, 1.12 mm (ZMH-K-64934), KUWAIT, Al-Salam Beach; 29°21.631'N, 47°57.204'E; 28.X.2014; V. Grintsov leg. Paratypes: • 1♀, 1.34 mm (ZMH-K-64935), same data as the holotype • 1 ♂ 1.1 mm; 4 ♀♀ up to 1.25 mm (ZMH-K-64936), Umm Al-Maradim Island; 28°40.778'N, 48°39.207'E; 11.XI.2014; V. Grintsov leg.
Eyes with 3 ommatidia; eyestalks with medium length, reaching proximal half of peduncular article 2 of antenna 2. Pereonites 2–7 with a pair of relatively short single lateral spine-like processes. The pleotelson has a relatively short anterior neck, length about 0.1 pleotelson length, lateral margins with 6 denticles each. Male pleopod 2 with an elongate, downwardly curved and distally pointed apex endopodal stylet.
Male: Body (Fig.
Head
(Fig.
Pereon
(Figs
Pleotelson
(Fig.
Antennula
(Fig.
Antenna
(Fig.
Mandible
(Fig.
Maxillula
(Fig.
Maxilla
(Fig.
Maxilliped
(Fig.
Pereopod 1
(Fig.
Pereopod 2
(Fig.
Pereopod 5
(Fig.
Pereopod 7
(Fig.
Pleopod 1
(Fig.
Pleopod 2
(Fig.
Pleopod 3
(Fig.
Penes
(Fig.
Female (Figs
Heterosignum behbehanii sp. nov. is most similar to H. elegans Shimomura & Mawatari, 2002 from Japan, as both of these species have lateral spine-like processes on pereonites 2–7, a pleotelson with 6 denticles on its lateral margins of the posterior part, and pleopod 2 with a slender very long, curved second article of the endopod. However, the new species is distinguished from H. elegans in having its notably shorter lateral spine-like processes on pereonites 2–7, a smaller anterior part of the pleotelson (about 0.1 vs. 0.4 times the total length of pleotelson), and the first pleopod being distally separate instead of distally connected.
The new species differs from Heterosignum unicornis (Kensley, 1976), the only species reported from the Indian Ocean (southern Indian Ocean, Amsterdam Island). Heterosignum unicornis has a stout mid-dorsal spine (horn) on the first pereonite, lacking lateral spine-like processes on pereonites 5–7, and a pleotelson with 4 denticles on its lateral margins.
1 | Pereonite 1 with strong mid-dorsal horn-shape spine | 2 |
– | Pereonite 1 without mid-dorsal horn-shape spine | 3 |
2 | Head with one stout mid-dorsal horn-shape spine; pereonite 1 with lateral spine-like processes | H. ohtsukai Shimomura & Mawatari, 2002 |
– | Head without mid-dorsal horn-shape spine; pereonites 1 and 7 without lateral spine-like processes | H. unicornis (Kensley, 1976) |
3 | Head without long anteriorly directed processes on the anterior margin | 4 |
– | Head with 2 long anteriorly directed processes on the anterior margin | H. bicornis Shimomura, 2011 |
4 | Eyestalks slender, medium or long, with a few ommatidia | 5 |
– | Eyestalks stout, short, without ommatidia | H. hashimotoi Shimomura, 2009 |
5 | Pereonites 2–4 and 6 with a pair of relatively short single lateral spine-like processes or not; anterior part of the pleotelson short, cylindrical, about 0.1 of the total length | 6 |
– | Pereonites 2–4 and 6 with a pair of very long single lateral spine-like processes; anterior part of the pleotelson long, cylindrical, about 0.4 of the total length | H. elegans Shimomura & Mawatari, 2002 |
6 | Pereonites 4, 5 and 7 without lateral spine-like processes; pleopod 2 with broad protopod, bearing 12 marginal setae, endopodal second article about 1.1 as long as protopod | H. mutsuensis Gamô, 1976 |
– | Pereonites 2–7 with short lateral spine-like processes; pleopod 2 with broad protopod, bearing 16 marginal setae, endopodal second article about 2.4 as long as protopod | H. behbehanii sp. nov. |
Uromunna ubiquita (Menzies, 1952), by original designation.
The most recent diagnosis to the genus is that of
The species is named in honour of Dr Faiza Yousef Al-Yamani, a pioneering figure who established the Oceanography Program at the Environment and Life Sciences Research Center at Kuwait Institute for Scientific Research (KISR) in 1991.
Holotype : • ♂, 0.78 mm (ZMH-K-64937); KUWAIT. Quaruh Island; 28°49.105'N, 48°46.553'E; 10. XI. 2014; V. Grintsov leg. Paratypes: • 1♀, 0.88 mm (ZMH-K-64938), same data as the holotype • 1♀, 0.78 mm (ZMH-K-64939), Al-Khiran; 29°38'48.47"N, 48°23'28.68"E; 05. I.2015; V. Grintsov leg. • 2 ♀♀, up to 0.75 mm (ZMH-K-64940), Auha Island; 29°22.32'N, 48°26.27'E; 10. II.2016; V. Grintsov leg. • 2 ♀♀, up to 0.8 mm, 1♂, 0.725 mm, 1 slide (ZMH-K-64941), Al-Nuwaiseeb; 28°34.792'N, 48°24.078'E; 07.I.2015; V. Grintsov leg. • 1♀, 0.787 mm, 1 slide (ZMH-K-64941), Failaka Island; 29°28.049'N, 48°17.838'E; 22.XII.2014; V. Grintsov leg.
Pleotelson 1.26 times longer than wide, 0.31 times of whole body, and lateral margins each with 2 denticles. Maxillipedal endite with three coupling hooks. Male pleopod 1 distal margin medial lobes convex, each lobe with three setae. Pleopod 2 protopod elongate, with distally rounded apex; endopod stylet extending just beyond apex of protopod, about 0.7 times as long as protopod. Pleopod 4 exopod distal tip with 1 elongate plumose seta.
Male: Body (Fig.
Head
(Fig.
Pereon
(Fig.
Pleonite 1 small, about 0.4 times as long as wide, without dorsal setae.
Pleotelson
(Figs
Uropod
(Fig.
Antennula
(Fig.
Antenna
(Fig.
Mandible
(Fig.
Maxillula
(Fig.
Maxilla
(Fig.
Maxilliped
(Fig.
Pereopod 1
(Fig.
Pereopod 2
(Fig.
Pereopod 4
(Fig.
Pereopod 7
(Fig.
Pleopod 1
(Fig.
Pleopod 2
(Fig.
Pleopod 3
(Fig.
Pleopod 4
(Fig.
Penes
(Fig.
Female (Figs
Uromunna alyamanii sp. nov. shares similarities with U. naherba Esquete, Wilson & Troncoso, 2014 from NW Iberian Peninsula, Spain, and U. jejuensis Kim, Lee & Karanovic, 2023 from the Mun Island, Sea of Japan. These similarities include the appearance of mouthparts, pereopods, and pleopods, especially a round distal apex of male pleopod 1 with three pairs of apical setae, the presence of denticles on the pleotelsonic lateral margins, and a female operculum with a terminal pair of setae. However, the present species also have distinct differences, such as a pleotelson with 2 lateral margin denticles on each side, a feature not found in the latter species.
The new species differs from U. sheltoni (Kensley, 1977) from South Africa, which has the distally concave pleopod 1, with 4 short apical setae (vs. distally rounded, with 3 short setae in the present species), and the shorter endopodal stylet of pleopod 2, which does not reach beyond the apex of the ramus.
1 | Pleotelson lateral margins denticles absent | 2 |
– | Pleotelson lateral margins denticles present, 2 denticles on each side | U. alyamanii sp. nov. |
2 | Pleopod 1 strongly curving laterally at apices, each apex with 2 pairs of setae along free mesial margin | U. brevicornis (Thomson, 1946) |
– | Pleopod 1 evenly tapering to apices; each apex with 3 subterminal setae | 3 |
3 | Pleopod 1 with rounded-truncate apices; pleopod 2 with acute apex, bearing 2 setae along mesial edge | U. humei Poore, 1984 |
– | Pleopod 1 with obliquely truncate apices; pleopod 2 with rounded-acute apex, bearing 1 subterminal seta | U. phillipi Poore, 1984 |
We would like to extend our special thanks to all the KISR staff for their invaluable assistance in collecting isopod samples in the field and processing them in the laboratory. We are also profoundly grateful for the crucial financial support from the Kuwait Petroleum Company (KPC) and the Kuwait Institute for Scientific Research (KISR); without them, this research would not have been possible. PLZ replace by: This publication is supported by a special fund provided by Kuwait Science Company (KSC). We would like to thank Dr Saskia Brix (Senckenberg Research Institute, Germany), Dr Brenda Doti (Universidad de Buenos Aires, Argentina) and one anonymous reviewer for their constructive suggestions and helpful comments. Finally, we thank Dr Maria Saburova (KISR) for her valuable support and assistance with the scanning electron microscope.
The authors have declared that no competing interests exist.
No ethical statement was reported.
No funding was reported.
Writing - original draft: VKP. Writing - review and editing: MAAK.
Valiallah Khalaji-Pirbalouty https://orcid.org/0000-0002-0892-7463
Manal Abdulrahman Al-Kandari https://orcid.org/0000-0003-0073-7929
All of the data that support the findings of this study are available in the main text.