International Journal of Advanced Culture Technology Vol.8 No.2 277-282 (2020) DOI https://doi.org/10.17703/IJACT.2020.8.2.277 IJACT 20-6-35 Redescription of the First Zoea of Microcassiope orientalis (Crustacea: Decapoda: Xanthidae) Seok Hyun Lee* Dept of Life Sciences, Silla University Korea [email protected] Abstract The first zoea of Microcassiope orientalis is described and illustrated from laboratory hatched materials. Comparisons with previous studies of the first zoeal stages in the Xanthidae from Korean waters, revealed that some former studies were incorrected. The first zoea of M. orientalis described by Ko was identical to the first zoea of Macromedaeus distinguendus described by Terada. In addition, zoeal stages of Nanocassiope granullipes described by Ko & Clark was revealed the zoeal stages of M. cassiopes. So, the first zoea of M. orientalis is redescribed and illustrated in detailed with color photo herein, and compare its morphological characteristics with previous described zoea of N. granulipes by Ko & Clark Keywords: redescription, first zoea, Xanthidae, Microcassiope orientralis, Nanocassiope granulipes 1. INTRODUCTION Currently, five species of the genus Microcassiope are recognized in the subfamily Xanthinae in the family Xanthidae [1]: Microcassiope granulimana, M. minor, M. orientalis, M. taboguillensis, and M. xantusii. Among them, two species (M. minor by Clark et al. [2], and M. orientalis by Ko, [3]) of the first zoea stages (M. minor by Clark et al. [2], and M. orientalis by Ko, [3]) in this genus have been recorded from the world. The only one species, M. orinetalis, has been recorded from Korea ([4]; [5]). During continuous comparisons with previous studies of the first zoea in the family Xanthidae from Korean waters. Some previous studies were revealed to be incorrected. The first zoea of M. orientalis described by Ko [3] was identical to the first zoea of Macromedaeus distinguendus described by Terada. In addition, zoeal stages of Nanocassiope granullipes described by Ko & Clark [6] was revealed the zoeal stages of M. cassiopes. Therefore, the purpose of this study is to re-describe and illustrate its first zoea with digital color photo, and compare its morphological characteristics with previous described zoea of N. granulipes by Ko & Clark [6]. 2. MATERIALS AND METHODS An ovigerous female Microcassiope orientalis was collected by SCUBA diving in about 20m depths from Geomun Island, Yeosu, Jeollanamdo, Korea on 1 August 2010. Female crab was reared in a glass beaker of 2,000 ㎖ at a constant seawater temperature of 22±1 ℃ and were fed on Artemia nauplii until zoeas hatched. The first zoeas were hatched on 9 August 2010 in the laboratory. The first zoeas were preserved in 95% ethyl Manuscript received: April 18, 2020/ revised: May 06, 2020/Accepted: May 12, 2020 Corresponding Author:[email protected] Tel:+82-51-999-6931, Fax: +82-51-999-5471 (Full Time) Lecturer, Dept. of Life Sciences, Silla Univ., Korea 278 International Journal of Advanced Culture Technology Vol.8 No.2 277-282 (2020) alcohol for examination. Living zoeas were taken digital photograph with a Leica EZ40 microscope and then processed in Photoshop. Zoeal specimens were dissected using the Leitz zoom stereomicroscope and appendages were examined under a Leitz Laborlux S microscope. Appendages were mounted in ethylene glycol and drawings were made with the camera lucida. Observations of setal counts on appendages and measurements were based on the mean of 10 specimens. The sequence of the zoeal description follows that of Clark et al. [7]. The long plumose natatory setae of the first and second maxillipeds were drawn truncated. The chromatophore patterns were observed with living zoeas. A micrometer was used for the zoeal measurements: Carapace length (CL) from the base of the rostrum to the most posterior carapace margin and rostral and dorsal spine length (RDL) from the tip of rostral carapace spine to the tip of the dorsal carapace spine. Specimens examined in present study and spent female were deposited in Silla University, Korea. Fig. 1. Color photos of adult and the first zoea of Microcassiope orientalis. A, adult of M. orientalis; B, the first zoeas of M. orientalis. 3. RESULT Microcassiope orientalis Takeda and Miyake, 1969 (Fig. 1A) First zoea (Figs. 1B, 2) Size: CL 0.52±0.05mm; SL 1.53±0.05 mm. Chromatophores (Fig. 1B): Black and yellow chromatophores which occurring between and behind eyes, on lateral expansion of carapace margin, basis of dorsal spine posteriorly, on basis of lateral spines anteriorly, on basis of each maxillipeds, and posterolateral margins of abdominal somites 2-5; Red chromatophores on telson and forks. Carapace (Figs. 1B, 2A, A’): Dorsal spine longer than CL, slightly longer than rostral spine, slightly curved distally, with several minute tubercles; rostral spine slightly shorter than protopod of antenna, with a spine distally; lateral spines short; 1 pair of posterodorsal setae present; each ventral margin with spinules; eyes sessile. Antennule (Fig. 2B): Uniramous; endopod absent; exopod with 2 long, stout aesthetascs, 1 shorter, thinner aesthetasc, 2 (1 long, 1 shorter) simple setae, all terminal. Redescription of the First Zoea of Microcassiope orientalis (Crustacea: Decapoda: Xanthidae) 279 Fig. 2. Microcassiope orientalis, the first zoea. A, lateral view; A’, lateral expansion of carapace; B, antennule; C, antenna; D, mandibles; E, maxillule; F, maxilla; G, first maxilliped; H, second maxilliped; I, dorsal view of abdomen and telson; I’, fork of telson. Scale bars= 0.3 mm (A, I), 0.1 mm (A’-D, G-I’), 0.05 mm (E, F). 280 International Journal of Advanced Culture Technology Vol.8 No.2 277-282 (2020) Antenna (Fig. 2C): Protopod slightly longer than rostral spine, spinulate on distal half, minute endopod spine present; exopod approximately 8% length of protopod, with 1 terminal seta. Mandibles (Fig. 2D): Asymmetrical; right molar with 2 teeth, left molar with 1 tooth, confluent with incisor process; palp absent. Maxillule (Fig. 2E): Coxal endite with 7 setae; basial endite with 5 setae and 2 teeth; endopod 2-segmented, proximal segment with 1 seta, distal segment with 6 (2 subterminal, 4 terminal) setae; exopod seta and epipod absent. Maxilla (Fig. 2F): Coxal endite bilobed, with 4+4 setae; basial endite bilobed, with 5+4 setae; endopod bilobed, with 3+5 setae; exopod (scaphognathite) margin with 4 plumose setae, 1 distal process. First maxilliped (Fig. 2G): Coxal segment with 1 seta; basis with 10 setae, arranged 2+2+3+3; endopod 5- segmented, with 3, 2, 1, 2, 5 (1 subteminal, 4 terminal) setae; exopod 2-segmented, distal segment with 4 long terminal plumose natatory setae. Second maxilliped (Fig. 2H): Coxa without seta; basis with 4 setae, arranged 1+1+1+1; endopod 3- segmented, with 1, 1, 5 (2 subterminal, 3 terminal) setae; exopod 2-segmented, distal segment with 4 long terminal plumose natatory setae. Abdomen (Fig. 2I): With 5 somites; somite 2 with 1 pair of lateral processes directed anteriorly; somite 3 with 1 pair of lateral processes directed posteriorly; somites 2-5 each with 1 pair of posterodorsal setae, respectively; somites 3-5 each with 1 pair of posterolateral spines, respectively; pleopod absent. Telson (Fig. 2I’): Each fork long, naked, with 1 stout lateral spine, 1 simple lateral seta and 1 stout dorsomedial spine; posterior margin with 3 pairs of setae. 4. DISCUSSION The first zoea of M. orientalis is identical to other the first zoeas of superfamily Xanthoidea suggested by Ko & Lee [8] as follows: well developed rostral and dorsal carapace spines and short lateral carapace spine; antennal exopod less than one third of protopod with one to three spines; endopods of maxillule and maxilla with 1, 2+4 setae, and 3+2+3 (rarely 2) setae, respectively; lateral processes on abdominal somites 2, 3; and fork of telson has on lateral seta, one lateral and dorsomedial spines. Morphological characteristics of the first zoea M. orientalis agree well with those of Nanocassiope granulipes (Rathbun, 1939) described by Ko & Clark [6] (Table 1), except in number of aesthetasc and seta on antennule and length of antennal exopod (Fig. 3). The difference in the antennule may be insignificant because a seta is sometimes confused as a minute aesthetasc under a microscope. The difference in the exopod/protopod ratio of antenna (8% in present study vs. 12% in Ko & Clark [6]) is due to measurement whether a terminal seta is included or not when measuring the length of antennal exopod. Hence, re-examined a spent female crab of N. granulipes used by Ko and Clark [6] to confirm species and identified as M. orientalis having defined carapace regions except fused mesogastric and posterogastric regions and a subdistal spine on a dactylus of the ambulatory leg (Lee & Ko [4]). Therefore, re-description of the zoeal stage of N. granulipes should be needed. Redescription of the First Zoea of Microcassiope orientalis (Crustacea: Decapoda: Xanthidae) 281 Table 1. Comparison of the characteristics of the first zoeas of Microcassiope orientalis and Nanocassiope granulipes Family Xanthidae Species Microcassiope orientalis Nanocassiope granulipes Reference Present study Ko and Clark, [6] Carapace dorsal, rostral, lateral spines Long, long, short Long, long, short Antennule 3 aesthetascs, 2 setae 4 aesthetascs, 1 seta Antenna protopod spinulate spinulate endopod present present exopd small (8%), 1 terminal seta small (12%), 1 terminal seta Maxillule coxal endite 7 setae 7 setae basial endite 5 setae 5 setae endopod 1, 2+4 setae 1, 2+4 setae Maxilla coxal endite 4+4 setae 4+4 setae basial endite 5+4 setae 5+4 setae endopod 3+5 setae 3+5 setae 1st maxilliped basis 2, 2, 3, 3 setae 2, 2, 3, 3 setae endopod 3, 2, 1, 2, 5 setae 3, 2, 1, 2, 5 setae 2nd maxilliped basis 1, 1, 1, 1 setae 1, 1, 1, 1 setae endopod 1, 1, 5 setae 1, 1, 5 setae Abdomen lateral processes 2, 3 somites 2, 3 somites Telson 1 lateral spine, 1 lateral seta, 1 lateral spine, 1 lateral seta, 1 dorsomedial spine 1 dorsomedial spine fork not spinulate not spinulate 282 International Journal of Advanced Culture Technology Vol.8 No.2 277-282 (2020) Fig.