Heteromysoides songkhlaensis, Yolanda & Sawamoto & Lheknim, 2019

Yolanda, Rofiza, Sawamoto, Shozo & Lheknim, Vachira, 2019, A new species in the genus Heteromysoides (Crustacea, Mysida, Mysidae) from Songkhla Lagoon, southern Thailand, Zoosystematics and Evolution 95 (2), pp. 535-542 : 536-538

publication ID

https://dx.doi.org/10.3897/zse.95.39214

publication LSID

lsid:zoobank.org:pub:E0B1DCB6-0357-45FC-A7D3-AB4E758EAC06

persistent identifier

https://treatment.plazi.org/id/DE6E674F-CEB3-4CAD-829C-8221F21E1F77

taxon LSID

lsid:zoobank.org:act:DE6E674F-CEB3-4CAD-829C-8221F21E1F77

treatment provided by

Zoosystematics and Evolution by Pensoft

scientific name

Heteromysoides songkhlaensis
status

sp. nov.

Heteromysoides songkhlaensis sp. nov. Figs 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Type material.

Holotype. Adult male (BL 3.2 mm) (NMST-Cr 26744), Thale Sap, 7°20'58.68"N, 100°25'31.56"E, Ban Bang Khiat, Tambon Bang Khiat, Singha-Nakhon District, Songkhla Province, Thailand, 19 January 2019, at 1.3 m of depth with salinity of 0.39 psu, over a muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda.

Allotype. Adult female with empty marsupium (BL 3.7 mm) ( PSUZC 20190119-02.01), Thale Sap Songkhla, 7°15'18.77"N, 100°28'11.86"E, Ban Pa Khad, Singha-Nakhon District, Songkhla Province, Thailand, 19 January 2019, at 1.3 m of depth with salinity of 0.47 psu, over a muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda.

Paratypes. 1 adult male (BL 3.6 mm, dissected) ( NSMT-Cr 26745), Thale Sap, 7°19'34.50"N, 100°24'31.45"E, Ban Koh Nang Kum, Koh Nang Kum, Pak Payoon District, Phattalung Province, Thailand, 18 May 2018, at 1.3 m of depth with salinity of 3.68 psu, over muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda; 1 adult male (BL 3.4 mm, dissected) ( PSUZC 20180618-01.01) Thale Sap Songkhla, 7°13'14.67"N, 100°31'24.12"E, Ban Bo Pab, Sathing Mor, Singha-Nakhon District, Songkhla Province, Thailand, 18 June 2018, at 1 m of depth with salinity of 1.67 psu, over muddy substrate, coll. V. Lhek nim, N. Tubtimtong and R. Yolanda; 1 adult male (BL 3.5 mm, dissected) ( PMBC 11806), Thale Sap, 7°20'58.68"N, 100°25'31.56"E, Ban Bang Khiat, Tambon Bang Khiat, Singha-Nakhon District, Songkhla Province, Thailand, 18 July 2018, at 0.6 m of depth with salinity of 2.72 psu, over a muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda; 1 adult female (BL 3.7 mm, dissected) ( PMBC 11807), Thale Sap, 7°16'30.89"N, 100°25'17.21"E, Ban Laem Chak, Pak Ror, Singha-Nakhon District, Songkhla Province, Thailand, 18 April 2018, at 1.5 m of depth with salinity of 15.1 psu, over muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda; 1 adult female (BL 3.1 mm, dissected) ( NSMT-Cr 26746), Thale Sap Songkhla, 7°11'45.16"N, 100°33'33.76"E, Ban Hua Khao, Hua Khao, Singha-Nakhon District, Songkhla Province, Thailand, 18 April 2018, at 1.4 m of depth with salinity of 24.8 psu, over a muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda; 2 adult females (BL 3.2 mm [dissected], 3.6 mm [not dissected]) ( NSMT-Cr 26747), Thale Sap, 7°20'58.68"N, 100°25'31.56"E, Ban Bang Khiat, Tambon Bang Khiat, Singha-Nakhon District, Songkhla Province, Thailand, 18 May 2018, at 1.1 m of depth with salinity of 7.43 psu, over muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda; 2 adult males (BL 3.6 mm, [dissected], 4.0 mm [not dissected]); 1 adult female (BL 3.6 mm, dissected) ( ZRC 2019.1095), Thale Sap Songkhla, 7°14'32.41"N, 100°25'50.57"E, Ban Tai, Pak Ror, Singha-Nakhon District, Songkhla Province, Thailand, 18 November 2018, at 1.2 m of depth with salinity of 5.25 psu, over muddy substrate, coll. V. Lheknim, N. Tubtimtong and R. Yolanda.

Description.

Head and cephalic appendages. Carapace with anterior margin obtusely produced into wide, triangular rostrum (Fig. 2C, D View Figure 2 ); cervical groove distinct at anterior two-fifths, posterior margin excavated, leaving last thoracic somite uncovered in dorsal view, but sufficiently covered laterally (Fig. 2A, B View Figure 2 ): antero-ventral corner rounded (Fig. 2A, B View Figure 2 ). Eye slightly depressed, subglobular in dorsal aspect; cornea comprise of small tube-like ommatidia situated in antero-lateral part without ocular process (Fig. 2C-E View Figure 2 ). Antennule with first segment of peduncle longer than wide, with dorsal projection bearing 3 setae (Fig. 2F, H View Figure 2 ); distolateral corner of first segment greatly produced anteriorly, distal part with 5 setae; second segment shortest, with dorsal projection bearing 2 setae and distal part with 2 setae; third segment subequal to first segment, with dorsal projection bearing 4 setae dorsally, middle part with 2 setae at the mesial margin for female while no seta on male, respectively and 2 setae at distomesial corner for male while 3 setae for female; the lobe completed with several long setae on male (Fig. 2G View Figure 2 ) while no long setae on female. Antennal peduncle more robust in male than female and reaching 0.8 length of antennular peduncle and the sympod rounded (Fig. 2I, J View Figure 2 ); antennal scale elongated, elliptical with apical suture, setose all round, reaching middle part of third segment of antennular peduncle, nearly 3 times as long as wide, not reaching distal end of antennal peduncle (Fig. 2I, J View Figure 2 ). Labrum triangular, without process or spine in anterior part but with expanded disto-lateral parts (Fig. 2K View Figure 2 ). Mandibular palp 3-segmented, second segment longest and widened at mid-length, with barbed setae on both margins, 3 on middle part of inner margin, 1 seta on proximal part of outer margin and 5 setae on the distal margin of the second segment (Fig. 2L View Figure 2 ); incisor process well developed and comprised of a series of teeth forming serrated sharp ridge; lacinia mobilis showing different shape in right and left mandibles, and spine row and molar process clearly visible (Fig. 2M View Figure 2 ). Maxillule well developed, basal lobe with spines densely, wider than precoxal lobe (Fig. 2N View Figure 2 ). Maxilla with 4 distal setae and smooth setae on exopod (Fig. 2O View Figure 2 ); distal segment of endopod longer than proximal one; basal and coxal endites well developed, with dense setae.

Thoracopods. Flagelliform part of first and eighth thoracopodal exopods composed of 8 segments (Figs 3A View Figure 3 , 4C View Figure 4 ), while second to seventh thoracopodal exopods with 9 segments (Figs 3C, E, G, I View Figure 3 , 4A, B View Figure 4 ). First thoracopodal endopod short and basis well developed, larger than endite; medial margins of carpus, propodus and dactylus heavily setose (Fig. 3A, B View Figure 3 ). Second thoracopodal endopod stout (Fig. 3C View Figure 3 ); basis with 2 setae; preischium with 1 seta, shorter than basis; ischium longer than preischium with 6 setae; merus longest, with 2 setae; carpopropodus 0.75 times as long as merus, with several barbed setae (Fig. 3D View Figure 3 ); dactylus 0.5 times as long as carpopropodus, 1.6 times as long as width, with several barbed setae (Fig. 3D View Figure 3 ). Third and fourth thoracopodal endopods similar in form (Fig. 3E, G View Figure 3 ) and more slender than second (Fig. 3C View Figure 3 ); basis with 2 setae; ischium slightly longer than merus, with 4-6 setae on inner margin; merus slightly shorter than carpopropodus; carpopropodus constituting 3 sub-segments with barbed setae, basal segment longest and second shortest; dactylus short, apex with long barbed seta and several setae (Fig. 3E-H View Figure 3 ). Fifth thoracopodal endopod longest (Fig. 3I View Figure 3 ), with similar morphological characters to sixth, seventh, and eighth (Fig. 4A-C View Figure 4 ). Sixth thoracopodal endopod (Fig. 4A View Figure 4 ) subequal in length to seventh and eighth (Fig. 4B, C View Figure 4 ); basis with 1 seta, ischium longer than merus, with several setae; merus with 6 setae; carpopropodus constituting 4 sub-segments, with several setae, basal segment longest, third segment shortest; dactylus short, with several setae. Penis (Fig. 4C View Figure 4 ) long, 0.8 times as long as ischium of eighth thocacopodal endopod, apex rounded, with several smooth setae.

Pleon and pleopods. Abdominal somites smooth, without hairs, spines or folds, ventral sternites without process, anterior 5 somites subequal in length, sixth somite 1.3 times as long as preceding somite (Fig. 2A, B View Figure 2 ). Five pleopods reduced to unsegmented lobes, not modified; first pleopod shortest, second to fourth ones subequal in length and fifth pleopod longest, 1.6 times as long as fourth (Fig. 4D-H View Figure 4 ).

Uropod and telson. Uropodal endopod slightly shorter than exopod, without spine on ventral side of statocyst region (Fig. 4I View Figure 4 ). Telson (Fig. 4K-N View Figure 4 ) subtriangular, 0.8 times as long as sixth abdominal somite, 1.3 times as long as basal width, excluding apical denticles, with 11-18 ar ticulated denticles in males and 12-19 in females on distal quarter margin (Table 1 View Table 1 ), increasing in length distally.

Etymology.

This species is named after the locality, Songkhla Lagoon, where of the specimens were found.

Distribution.

This species was captured in brackish waters above a muddy substratum at Thale Sap and Thale Sap Songkhla, Songkhla Lagoon, southern Thailand.

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Mysida

Family

Mysidae

Genus

Heteromysoides