[Crustacea • 2025] Quadrimaera sirindhornae • A New Species of Quadrimaera (Amphipoda: Maeridae) from Coral Reefs of Chon Buri Province, Thailand

 

Quadrimaera sirindhornae    

Boonyanusith, Putchakarn & Wongkamhaeng, 2025

 Tropical Natural History. Suppl. 8 

แอมฟิพอดเจ้าฟ้า  ||  DOI: doi.org/10.58837/tnh.25.8.267553

Abstract

Quadrimaera sirindhornae sp. nov. was described from specimens collected from algae in a coral reef in Chon Buri Province, Thailand. The new amphipod species can be distinguished from its closest relative by its accessory flagellum with seven articles, gnathopod 2 propodus 1.8x longer than wide, uropod 3 ratio of outer ramus and peduncle is 1.2. The illustration and comparison of diagnostic charac-teristics in male Quadrimaera reported in Southeast Asia were provided.

Keywords: Amphipoda, new species, algal bed, Gulf of Thailand

Quadrimaera sirindhornae sp. nov. 

แอมฟิพอดเจ้าฟ้า

Chaichat Boonyanusith, Sumaitt Putchakarn and Koraon Wongkamhaeng. 2025. A New Species of Quadrimaera (Amphipoda: Maeridae) from Coral Reefs of Chon Buri Province, Thailand.  Tropical Natural History. Suppl. 8;  472-480. DOI: doi.org/10.58837/tnh.25.8.267553 [2025-11-17]

[Crustacea • 2024] Sipadantonius roihani • A New Genus and Species of Pseudocyclopidae Giesbrecht, 1893 (Copepoda: Calanoida) from the marine cave “Turtle Tomb” of Sipadan Island, Sabah, Malaysia

Sipadantonius roihani  

Boonyanusith, Wongkamhaeng & Azman, 2024

  

DOI: doi.org/10.3897/zookeys.1219.133132 

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Abstract

A new genus and species of the family Pseudocyclopidae, Sipadantonius roihani gen. et sp. nov., was described based on specimens collected using a light trap in the marine cave of Sipadan Island, Sabah, Malaysia. The new genus is most related to Pinkertonius, primarily based on the similarity observed in the armament of ancestral segment IV of the male antennules, the armament of the female P5 Exp-3, the segmentation of the male P5, the armament of the maxillular basal exite, and the relative length of the ancestral segment XXVII of the antennules. Nevertheless, it distinguishes itself from Pinkertonius and all other genera of the family by the absence of the lateral seta of the basis of all swimming legs, the presence of an inner seta on the coxa of the female P5, the reduction of furcal setae I and III, as well as the specific armament of the ancestral segment XX of the antennules and the maxillular coxal endite. The female of Sipadantonius roihani gen. et sp. nov. has aesthetascs on the ancestral segments IV and XX of the antennules, as well as six setae on the maxillular coxal endite, exhibiting the most plesiomorphic characteristics of the family Pseudocyclopidae. The latter characteristic has not been recorded in the order Calanoida. It was hypothesised that the new species was a particle feeder living in the pelagic zone of the marine cave. The existence of the new species supported the assumption that the regional distribution of the family Pseudocyclopidae exhibited the Tethyan track, which might have been the subsequent result of the colonisation of the habitats prior to the closure of the Tethys Sea.

Key words: Crustacea, Southeast Asia, systematics, taxonomy, Zooplankton

Sipadantonius roihani gen. et sp. nov. female:
A habitus, dorsal view B habitus, lateral view C urosome, ventral view D urosome, lateral view E genital double-somite, ventral view F furcal rami, dorsal view G furcal rami, lateral view. Arrowheads indicate integumental pores.

Scale bars: 200 μm (A, B); 100 μm (C, D); 50 μm (E−G).

Sipadantonius roihani gen. et sp. nov. photographs of lateral surface of basis of swimming legs, female (A−E) and male (F):
A posterior hyaline process on basis of P1 (indicated by arrow) B P1 C P3 D P4 E, F P5. Arrowheads indicate cuticular windows on lateral margin of basis. Scale bars: 10 μm.

Order Calanoida Sars, 1903

Superfamily Pseudocyclopoidea Giesbrecht, 1893

Family Pseudocyclopidae Giesbrecht, 1893

Genus Sipadantonius gen. nov.

Etymology: Named after the type locality, Sipadan Island, Sabah, Malaysia, in combination with the -tonius stem from the existing generic name Pinkertonius Bradford-Grieve, Boxshall & Blanco-Bercial, 2014, alluding to the similarity of the genus Pinkertonius. The gender is masculine.

 Sipadantonius roihani sp. nov.

Etymology: The specific epithet was conferred in honour of Mr Roihan Han, a Malaysian deep dive record holder (at a depth of 164 m), who also led the Turtle Tomb exploration activity. Consequently, the name is a noun in the genitive singular.

Chaichat Boonyanusith, Koraon Wongkamhaeng and Abdul-Rahim Azman. 2024. Sipadantonius roihani gen. et sp. nov., A New Genus and Species of Pseudocyclopidae Giesbrecht, 1893 (Copepoda, Calanoida) from the marine cave “Turtle Tomb” of Sipadan Island, Sabah, Malaysia. ZooKeys. 1219: 303-329. DOI: doi.org/10.3897/zookeys.1219.133132

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[Crustacea • 2023] Cerapus rivulus • A New Species of Cerapus (Amphipoda: Senticaudata: Ischyroceridae) from Mae Klong Estuary, Gulf of Thailand, with A Discussion on their nesting and types of mating behaviour

Cerapus rivulus 

Katnoum, Saetung Keetapithchayakul, Rahim & Wongkamhaeng, 2023

  

 DOI: 10.3897/zse.99.107974

 Abstract

The first representative of the genus Cerapus in the Gulf of Thailand, Cerapus rivulus sp. nov., is described from specimens sampled from Mae Klong Estuary, the inner Gulf of Thailand. The main identifying characteristics of this new amphipod species are pereonites 1 and 2 without constriction; male gnathopod propodus palm transverse with long posterior defining tooth and well-developed anterodistal recurved tooth adjacent to propodus articulation; pereopod 6 coxa without fine fringe setae ventrally, basis with setae on posterior margin; and telson with deep cleft. An updated identification key for the 25 known species in the genus is also presented. A discussion on their nesting and types of mating behaviour is provided.

Key Words: Amphawa, Cerapus, mating behaviour, nesting behaviour

  

Cerapus rivulus sp. nov., holotype, male (THNHM -19377).
A. Habitus of the male holotype; B. Antenna 1; C. Antenna 2; D. Gnathopod 1; E. Palm of gnathopod 1; F. Gnathopod 2; G. Palm of gnathopod 2. Scale bars: 0.2 mm.

Cerapus rivulus sp. nov.
 A. Holotype male lateral (THNHM -19377); B. A specimen in its tube with protruding head and antennae; C. Paratype female front (THNHM-19379).

Chanikan Katnoum, Tosaphol Saetung Keetapithchayakul, Azman Abdul Rahim and Koraon Wongkamhaeng. 2023. A New Species of Cerapus (Amphipoda, Senticaudata, Ischyroceridae) from Mae Klong Estuary, with A Discussion on their nesting and types of mating behaviour. Zoosystematics and Evolution. 99(2): 557-574. DOI: 10.3897/zse.99.107974

 

[Crustacea • 2022] Floresorchestia amphawaensis & F. pongrati • Two New Species of the Genus Floresorchestia (Amphipoda: Talitridae) from Amphawa Estuary, Samut Songkhram Province, Thailand

FA. Floresorchestia amphawaensis sp. nov.  
FP. F. pongrati sp. nov.  
Amphawa District, Samut Songkhram, Thailand. 

Suklom, Keetapithchayakul, Rahim & Wongkamhaeng, 2022

DOI: 10.3897/zse.98.83749

Scale bars: 1 mm 

Abstract

Two new species of Floresorchestia (Crustacea: Amphipoda) are described from Amphawa Estuary, Samut Songkhram Province, Thailand. Floresorchestia amphawaensis sp. nov. is a riparian-hoppers living near agricultural and urban areas, being distinguished by the following character states: left mandible lacinia mobilis 4-dentate; gnathopod 2 palm reaching about 34%; telson as broad as long, with four robust setae per lobe. Floresorchestia pongrati sp. nov. are described as riparian-hoppers living in the moist area near Mae Klong canal banks with a unique left mandible lacinia mobilis 5-dentate; gnathopod 2 palm reaching 30% and telson with seven robust setae per lobe. The status and the problem of diagnostic character states of the genus Floresorchestia are discussed.

Key Words: Floresorchestiinae, riparian-hoppers, Southeast Asia, Talitridae

Male habitus of Floresorchestia spp. 
FA. Floresorchestia amphawaensis sp. nov. holotype, male, 7.8 mm (THNHM-lv-18763), Amphawa District, Samut Songkhram, Thailand; 
FP. F. pongrati sp. nov. holotype, male, 10 mm (THNHM-lv-19369), Amphawa District, Samut Songkhram, Thailand.

 Scale bars: 1 mm (FA, FP).

Anotai Suklom, Tosaphol Saetung Keetapithchayakul, Azman Abdul Rahim and Koraon Wongkamhaeng. 2022. Two New Species of the Genus Floresorchestia (Crustacea, Amphipoda, Talitridae) from Amphawa Estuary, Samut Songkhram Province, Thailand. Zoosystematics and Evolution. 98(2): 285-303.  DOI:  10.3897/zse.98.83749

[Crustacea • 2022] Thailandorchestia rhizophila • A New Genus and Species of Driftwood Hopper (Amphipoda: Protorchestiidae) from Thailand

Thailandorchestia rhizophila

 Wongkamhaeng, Dumrongrojwattana, Sumitrakij & Saetung Keetapithchayakul, 2022

 

DOI: 10.3897/zookeys.1099.82949

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Abstract

During a scientific survey, a new genus of driftwood hopper was found in mangrove roots in Ko Kut District, Trat Province, Thailand. We placed this new genus, Thailandorchestia gen. nov., within the family Protorchestiidae. The new genus can be distinguished from the remaining genera by uropod 1 outer ramus with robust setae, uropod 2 outer ramus without robust setae, and pereopod 7 basis without a posterodistal lobe. The type species of Thailandorchestia gen. nov., Thailandorchestia rhizophila sp. nov., is described herein, and an updated key to the genera of the family Protorchestiidae is provided.

Keywords: Description, Ko Kut District, marsh hopper, Talitroidea, Thailandorchestia gen. nov.

Thailandorchestia rhizophila sp. nov.

 a holotype, male, 8.04 mm, THNHM-Iv- 18760

b allotype, female, 7.80 mm, THNHM-IV- 18961

c rotting mangrove log, habitat of Thailandorchestia rhizophila sp. nov. 

Thailandorchestia rhizophila sp. nov. holotype, male, 8.04 mm, THNHM-Iv- 18760.

Scale bars: 1 mm.

Systematics

Order Amphipoda Latreille, 1816

Suborder Senticaudata Lowry & Myers, 2013

Family Protorchestiidae Myers & Lowry, 2020

Genus Thailandorchestia gen. nov.

Diagnosis: Protorchestiidae with maxilliped palp article 2 distomedial lobe absent. Mandible left lacinia mobilis 4-dentate. Gnathopod 2 coxal gill simple. Pereopod 4 carpus significantly shorter than carpus of pereopod 3. Pereopods 6–7 sexually dimorphic (male merus and carpus incrassate). Pereopod 7 posterodistal lobe absent. Uropod 1 peduncle distolateral robust setae present, very large (1/3–1/2 length of outer ramus); inner ramus linear, not modified; outer ramus with marginal robust setae. Uropod 2 outer ramus without marginal robust setae. Uropod 3 peduncle with 2 robust setae; ramus shorter than peduncle, linear (narrowing). Telson apically incised, with 2 robust setae per lobe.

Etymology: The generic name, Thailandorchestia gen. nov., is derived from “Thailand” in combination with the Orchestia stem.

Type locality: Mangrove forest near Ban Ao Prao Beach (11°35'40.2"N, 102°33'52.6"E), Trat Province, Thailand.

Ecological type: Driftwood hoppers (virtually confined to rotting driftwood where they live in galleries, consuming rotting driftwood and reproducing with relatively small broods).

 Thailandorchestia rhizophila sp. nov. 

Diagnosis: As for the genus unless otherwise stated. Antenna 1 long, reaching from midpoint to end of article 5 of antenna 2 peduncle. Eye medium (1/5–1/3 of head length). Gnathopod 1 not sexually dimorphic, palm transverse, dactylus shorter than palm. Gnathopod 2 sexually dimorphic (male subchelate, female mitten-shaped). Pleopod 1 outer ramus subequal in length to peduncle. Pleopod 3 outer ramus longer than peduncle.

Ecology: Driftwood hoppers, living inside rotten logs and mangrove roots in the softest part under the bark. The mangrove forest is located near a small creek 50 meters from the beach. The sediment in the forest is muddy sand mixed with leaf litter.

Etymology: The specific epithet refers to the habitat of this amphipod, which is also found inside mangrove roots.

Habitat: Mangrove wood, inside roots and rotting logs.

Distribution: Thailand, Ko Kut District, Inner Gulf of Thailand.

Koraon Wongkamhaeng, Pongrat Dumrongrojwattana, Ratchaneewarn Sumitrakij and Tosaphol Saetung Keetapithchayakul. 2022. Thailandorchestia rhizophila sp. nov., A New Genus and Species of Driftwood Hopper (Crustacea, Amphipoda, Protorchestiidae) from Thailand. ZooKeys. 1099: 139-153.  DOI: 10.3897/zookeys.1099.82949

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