The cyst hatching pattern of the Thai fairy shrimp, Branchinella Thailandensis Sanoamuang, Saengphan & Murugan, 2002 (Anostraca)

We investigated factors influencing the hatching of the fairy shrimp, Branchinella thailandensis in relation to brood order, and also responses of cysts to wet and dry periods. Male-female pairs of B. thailandensis were cultured under static conditions at room temperature and fed ad libitum micro-algae (Chlorella sp.). Deposited cysts of the first, sixth and eleventh broods were monitored for cyst hatching under wet and dry conditions. Cyst hatching was scored daily for 5 days after incubation. Freshly laid cysts, immediately incubated, did not hatch in any of the experimental conditions (wet/dry). On the contrary, undried cysts immersed in their parental medium for 4 weeks showed the highest hatching in all brood treatments (76.67, 94.67, and 99.33% of the first, sixth, and eleventh broods, respectively). The cysts of the first brood hatched less successfully than did those of the sixth and eleventh broods. Cyst hatching mostly took place within 24 hours after incubation. The present study shows that a wet period has a strong influence on the cyst hatching success of B. thailandensis. The cysts require a period of retention in the parental medium for 2-4 weeks to complete their embryonic development before hatching. Hatching of the three representative broods showed a different pattern for each brood. The early broods required a longer wet period than did the late broods. In contrast to the hatching behaviour of many other species, drying is not absolutely essential for cyst hatching of this species. © Koninklijke Brill NV, 2005

A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

Copyright © 2019 Magnolia Press. A new species of Moina Baird, 1850 (Cladocera: Moinidae) is described based on material collected from Thailand (South-East Asia). In tropical Asia, Moina siamensis sp. nov. could be confused easily with M. weismanni Ishikawa, 1896, because of morphological similarities in parthenogenetic females and males of both species. The outstanding difference between these two taxa concerns the structure of the ephippium in gamogenetic females, which is highly visible under light and scanning electron microscopes. The mature ephippium of M. weismanni is strongly tuberous, with distinct borders between cells, whereas the ephippium of M. siamensis sp. nov. is significantly less tuberous, with prominent longitudinal lines in its central region. Since gamogenetic females only appear sporadically in moinid populations, distribution ranges of M. siamensis sp. nov., M. weismanni and sibling taxa must be clarified precisely using genetic markers in the future. Preliminary investigations of the ephippium structure may be useful for estimating the differences between populations, thus revealing much diversity within Moinidae

A new species of Moina Baird, 1850 (Cladocera: Moinidae) from Thailand

Copyright © 2019 Magnolia Press. A new species of Moina Baird, 1850 (Cladocera: Moinidae) is described based on material collected from Thailand (South-East Asia). In tropical Asia, Moina siamensis sp. nov. could be confused easily with M. weismanni Ishikawa, 1896, because of morphological similarities in parthenogenetic females and males of both species. The outstanding difference between these two taxa concerns the structure of the ephippium in gamogenetic females, which is highly visible under light and scanning electron microscopes. The mature ephippium of M. weismanni is strongly tuberous, with distinct borders between cells, whereas the ephippium of M. siamensis sp. nov. is significantly less tuberous, with prominent longitudinal lines in its central region. Since gamogenetic females only appear sporadically in moinid populations, distribution ranges of M. siamensis sp. nov., M. weismanni and sibling taxa must be clarified precisely using genetic markers in the future. Preliminary investigations of the ephippium structure may be useful for estimating the differences between populations, thus revealing much diversity within Moinidae

Current knowledge of the South East Asian large branchiopod Crustacea (Anostraca, Notostraca, Laevicaudata, Spinicaudata, Cyclestherida)

The large branchiopod crustaceans (fairy shrimp, tadpole shrimp and clam shrimp) of South East (SE) Asia have only recently been examined with scientific vigor. Although more than 70 species have been reported for Asia and Indonesia, only six native taxa and one introduced species are known from SE Asia. The majority of records are from Thailand, with fewer than three records each from Laos, Myanmar, Malaysia, Cambodia, Vietnam, and Singapore. Eleven genera reported from adjacent regions may potentially occur in SE Asia. Spinicaudatan clam shrimp have been collected from Thailand and Cambodia, but have not been identified beyond genus. Four of the five native fairy shrimp species are endemic to SE Asia. The limited distributions of these few taxa suggest that this region has a distinct branchiopod fauna. In addition, we present new species and records of clam shrimp from Thailand. Future survey efforts will undoubtedly reveal additional taxa

Macrobrachium prachuapense Saengphan & Panijpan & Senapin & Laosinchai & Suksomnit & Phiwsaiya 2021, sp. nov.

Macrobrachium prachuapense Saengphan & Panijpan, sp. nov. ( Figs. 2 – 4 ) Material examined. Holotype: male (carapace length (CL) 8.8 mm), 6 April 2018, Khao Chao subdistrict, Pran Buri district, Prachuap Khiri Khan Province (12°20.898′ N, 99°41.829′ E). Paratypes: 7 males (CL 5.9–9.4 mm) and 11 females (5.3–9.0 mm), same location and date as holotype. Others: 4 males (6.1–9.2 mm) and 5 females (5.5–7.8 mm), 7 April 2018, Huai Mae Phriang subdistrict, Kaeng Krachan district, Petchaburi Province (12°57.565′ N, 99°24.101′ E). The holotype (THNHM-Iv-18710) and some paratype specimens (THNHM-Iv-18711, THNHM-Iv- 18712, and THNHM-Iv-18713) of the described species were deposited at the Thailand Natural History Museum. Other specimens were kept at Suphanburi College of Agriculture and Technology, the workplace of the first author. Largest male: total length 42.0 mm, carapace length 9.4 mm (fig. 2) Largest ovigerous female: total length 39.0 mm, carapace length 9.0 mm. Description. (Fig. 3A) Rostrum: straight, dorsal margin convex, extending slightly beyond end of antennal peduncle, subequal to half of carapace length; upper part having 11–15 teeth (usually 11–12), 3–4 teeth behind post orbital margin; lower part having 1–4 teeth (usually 2). Carapace: smooth with fine spinules at antero-ventral surface; antennal spine well developed with pointed end and situated below orbital angle (suborbital angle); hepatic spine smaller than antennal spine and located slightly behind and lower than antennal spine; paired hepatic spines situated between upper first and third teeth of rostrum on carapace. Abdomen: fourth thoracic sternite without median process; sixth abdominal somite 1.40–1.53 times as long as fifth; first, second, and third abdominal sternites having transverse ridges with median teeth only on first and second; preanal region with rounded ridge. Telson: upper telson (fig. 3B) smooth and 1.52–2.20 times length of sixth segment with 2 dorsal paired spines; tail tapering toward rear with pointed end (median spine), each side flanked by 2 spines, outer lateral spine and inner intermediate spine; several pairs of plumose setae found between 2 flanking spines; lateral spines similar in size to dorsal spines; well-developed intermediate spines 2–3 times length of median spine. Eyes: well developed with cornea diameter as long as stalk. Basal segment of antennal peduncle: broad, stylocerite distinctly pointed, reaching to about one-third of basal segment; anterolateral tooth reaching about middle of second segment; second segment as long as third. Scaphocerite (fig. 3C): length 2.78 times width, outer lateral side straight. Epistome (fig. 3D): trilobed by deep depression, but occasionally anteromedian lobe indistinct. Mandibular palp (fig. 3E): slender with three segments, incisor process robust. Maxillular palp (fig. 3F): bilobed, upper lobe stout with apical and subapical setae, lower lobe stout with distal blunt knob bearing short sinuous apical seta. Maxillary palp (fig. 3G): simple without distal setae, basal endite deeply bilobed, scaphognathite normal. First maxilliped (fig. 3H): palp with apical setae, basal and coxal endites distinct, flagellum of exopod with numerous distal plumose setae, epipod bilobed. Second maxilliped (fig. 3I): with normal endopod, flagellum with numerous distal setae, epipod simple. Third maxilliped (fig. 3J): with robust endopod, exopod with numerous distal plumose setae, reaching up to distal margin of ischiomerus. First pereiopod (fig. 3K): slender, end of carpus reaching end of scaphocerite, equal in length, similar in form; palm as long as finger, carpus 1.80 times as long as chela, merus shorter than carpus. Second pereiopod (fig. 4): distinctly unequal in length but similar in shape; major second pereiopod reaching beyond scaphocerite by end of merus, as long as or prolonging to noticeably longer than total length; palm, finger, and on proximal ½–4/5 on dorsal and ventral parts of carpus covered with long velvet setae; merus not inflated, 4.25 times as long as height, subequal in length to palm, covered with numerous spinules over its length and sparsely with long velvet setae on certain spots; carpus elongated and subcylindrical, 2.75 times as long as height, with numerous spinules over its length; palm comparatively slender, subequal or shorter than fingers, 3.2 times as long as width, on proximal 1/5 of both lateral sides covered with spinules; fingers equal or longer than palm, 15–28 teeth on cutting edges, curved inwards, tips crossing and small gaping when closed. Minor second pereiopod: short, about 0.74–0.9 times of total length; fingers 1.3–2.0 times as long as palm, with numerous teeth (13–15 teeth) on proximal ¾–4/5 of both cutting edges; merus 1.5–1.6 times as long as carpus; palm subequal to carpus, 2.7 times as long as wide, with setae as on major second pereiopod. Last three pereiopods: slender, similar in form; propodus, carpus, and merus covered with spinules and setae. Third pereiopod (fig. 3L): reaching or nearly so to end of scaphocerite; propodus 2.72–3.08 times as long as dactylus with 7 movable spines on postero-lateral margin. Fifth pereiopod: somewhat slenderer than third, reaching or nearly so to distal margin of scaphocerite. First pleopod: endopod not reaching distal half of exopod, inner margin concave, outer margin slightly convex. Appendix musculina of male: longer and stouter than appendix interna with numerous stiff setae. Uropodal diaeresis: with inner movable spine (fig. 3M) longer than outer angle. Ovigerous females: with eyed eggs 1.10×1.45 – 1.28× 1.75 mm in diameter, 25–45 per ovigerous female. Etymology. The specific name “ prachuapense ” refers to the collection site of the holotype, Prachuap Khiri Khan Province, which is commonly called Prachuap. Molecular phylogeny. DNA sequences: COI 667 base pairs (bp), consensus alignment 678 bp; 18S 1446 bp, consensus alignment 1458 bp. The COI alignment contained 293 variable sites, 245 of which were informative. The 18S alignment contained 127 variable sites, 62 of which were informative. However, only five of these 62 informative sites were useful for phylogenetic analysis within the Macrobrachium pilimanus species group. Genetic distances: Table 3 shows the pairwise p -distances among the COI sequences of Macrobrachium prachuapense sp. nov. and M. naiyanetri. It clearly indicates that M. prachuapense sp. nov. is significantly different from M. naiyanetri from the southern part of Thailand from where the holotype was collected. Table 4 shows the average interspecific p -distances among the COI sequences of the clades containing multiple closely-related sequences (pairwise p -distances <8%). Table 5 shows the average intraspecific p -distance among the COI sequences within each clade. The clades in Tables 4 and 5 are based on the phylogenetic relationship in fig. 5. Phylogenetic relationship (fig. 5): Based on the combined (COI and 18S) sequences, Macrobrachium prachuapense sp. nov. is novel and different from the other closely related species. The novel prawn and M. naiyanetri with COI accession numbers MT235951 and MT235960 form monophyletic clade (clade A), posterior probability 1; clade A and other M. naiyanetri (clade B) form monophyletic clade (clade P), posterior probability 0.94; clade P and M. forcipatum (clade C) form monophyletic clade (clade Q), posterior probability 1; clade Q and M. palmopilosum Siriwut et al., 2020 (clade D) form monophyletic clade (clade R), posterior probability 0.76; clade R and M. malayanum with COI accession numbers MT235965 –6 (clade E) form monophyletic clade (clade S), posterior probability 0.59; M. puberimanus Siriwut et al., 2020 and M. sp. (cf. dienbienphuense) form monophyletic clade (clade H), posterior probability 1; clade H and M. dienbienphuense (clade G) form monophyletic clade (clade T), posterior probability 1; clade T, M. hirsutimanus (Tiwari, 1952) (clade I), and M. eriocheirum (clade J) form monophyletic clade (clade U), posterior probability 1; clades S and U and M. malayanum with COI accession numbers MT235959 and MT235964 (clade F) form monophyletic clade (clade V), posterior probability 1; clade V and M. sirindhorn Naiyanetr, 2001 (clade K) form monophyletic clade (clade W), posterior probability 1; M. niphanae Shokita & Takeda, 1989 (clade L) and M. chainatense Saengphan et al., 2019 (clade M) form monophyletic clade (clade X), posterior probability 1; clades W and X form monophyletic clade (clade Y), posterior probability 1; clade Y and M. saengphani Saengphan et al., 2020 form monophyletic clade (clade Z), posterior probability 0.56; M. sintangense (de Man, 1898) (clade N) and M. suphanense Saengphan et al., 2018 (clade O) form monophyletic clade (clade AA), posterior probability 1; M. lanchesteri (de Man, 1911) and M. rosenbergii (de Man, 1879) form monophyletic clade (clade AB), posterior probability 1; clades AA and AB form monophyletic clade (clade AC), posterior probability 0.57; clades Z and AC are sisters, posterior probability 1.Published as part of Saengphan, Nukul, Panijpan, Bhinyo, Senapin, Saengchan, Laosinchai, Parames, Suksomnit, Auaree & Phiwsaiya, Kornsunee, 2021, Morphology and molecular phylogeny of Macrobrachium prachuapense sp. nov. (Decapoda: Palaemonidae) from Southern Thailand, pp. 428-442 in Zootaxa 4966 (4) on pages 432-437, DOI: 10.11646/zootaxa.4966.4.2, http://zenodo.org/record/473871

Morphology and molecular phylogeny of Macrobrachium saengphani sp. nov. (Decapoda: Palaemonidae) from Northern Thailand

A small wild prawn of the genus Macrobrachium, found in Chiang Rai Province, Northern Thailand has some morphological features resembling four other closely related species, M. lanchesteri, M. peguense, M. kunjuramani, and M. chainatense. However, it is distinguishable from the above species in terms of distinctive golden colored antennules; number of teeth on the rostrum; number of teeth on the cutting edges of the second pereiopod; and length of carpus relative to that of chela on the second pereiopod. Moreover, DNA analysis places it far apart on the phylogenetic tree from the related species in the genus. </jats:p

Morphology and molecular phylogeny of Macrobrachium saengphani sp. nov (Decapoda: Palaemonidae) from Northern Thailand

Saengphan, Nukul, Panijpan, Bhinyo, Senapin, Saengchan, Laosinchai, Parames, Suksomnit, Auaree, Phiwsaiya, Kornsunee (2020): Morphology and molecular phylogeny of Macrobrachium saengphani sp. nov (Decapoda: Palaemonidae) from Northern Thailand. Zootaxa 4868 (4): 531-542, DOI: https://doi.org/10.11646/zootaxa.4868.4.

&lt;p&gt;&lt;strong&gt;&lt;em&gt;Macrobrachium&lt;/em&gt; &lt;em&gt;chainatense&lt;/em&gt; sp. nov. (Decapoda: Palaemonidae): a freshwater prawn from Thailand based on morphology and molecular phylogeny&lt;/strong&gt;&lt;/p&gt;

Many species of freshwater prawns, large and small, inhabit Southeast Asian countries. In Thailand alone, there have been recent reports of new species in the genus Macrobrachium. Morphological differentiation and, recently, DNA sequence differences have been used to distinguish new species from valid ones. Macrobrachium chainatense (Decapoda: Palaemonidae), a small freshwater prawn found in Thailand, is now established as a new species based on both morphological and genetic criteria. Among Thailand Macrobrachium prawns, M. chainatense has smallest body size, largest egg size, and 3–5 teeth on the cutting edges. The most closely related Macrobrachium species to M. chainatense in terms of COI and 18S DNA sequences is M. niphanae. Their COI sequences differ by 7.3% while their 18S sequences are basically identical in all but one site. Observations of some aspects of this prawn in captivity are also utilized to establish its unique species status. This prawn may be useful as a source of cooked food for human consumption. </jats:p