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Identification of Larval Fish Family: Monacanthidae
Presented by: Edwison Setya F. *) Presented in Advanced Regional Workshop on Larval Fish Identification and Fish Early Life History Science, 26 May – 15 June 2008 in Seafdec TD, Samut Prakan, Thailand.
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Review of Morphological Features
Body shape Deep to elongate, becoming angular with growth. Compressed. Deep, becoming deeper with growth, but remaining rounded. Body depth preflex 30-64 proportion of SL postfex 12-58 56-63 Myomeres 17-31 20-22 Preopercular tuft Small to large Absent Tail pigment in preflexion Present Pelvis Barbed and prominent to not externally visible Not externally visible Dorsal fin spine Forms before soft rays and flexion (2.1 mm), weakly to strongly armed Forms after soft rays and flexion (3-5 mm), unarmed to at least 6 mm. Dorsal fin soft rays Moderate to many (26-51) Few to moderate (22-30)
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Review of Morphological Features (contd.)
Size at flexion mm mm Notochord tip Long and persist in postflexion larvae Doesn't persist in postflexion larvae Identified taxa included Aluterus, Amanses, Cantherhines, Monacanthus, Oxymonacanthus, Pseudalutarius, Stephanolepis, Thamnaconus Brachaluteres, Paraluteres, Rudarius.
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Review of Morphological Features (contd.)
Table of Meristic Character Genus D A P1 C Vert Acreichthys II 25-29 10-12 12 7+13 Aluterus II 46-54 13-15 7+(14-16) Amanses II 22-25 13 7+12 Anacanthus I 56-62 8-10 7+(22-24) Brachaluteres II 20-27 Cantherhines II 28-35 11-15 Cantheschenia II 32-36 10-14 Chaetodermis II 23-25 11-13 Colurodontis II 26-31 Eubalichthys 33-37 12-14 Lalmohania 25-28 10-11 Monacanthus II 27-34 11-14 Oxymonacanthus II 23-32 8+(17-18) Paraluteres II 24 11-12 7+(13-14) Paramonacanthus II 24-34 10-13 (6-7)+(12-13)
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Review of Morphological Features (contd.)
Table of Meristic Character Genus D A P1 C Vert Pervagor II 25-36 10-14 12 7+12 Pseudalutarius II 41-46 11-12 8+(18-21) Pseudomonacanthus II 27-34 10-13 Rudarius II 20-28 7+(12-13) Stephanolepsis 29-34 Thamnaconus II 30-37 12-16
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Information of Sampling
This sample is taken from Southern of South China Sea (SCS). Especially in Western Kalimantan waters, around Natuna islands. Taken on mid year 2005, in the collaborative research between Seafdec and Indonesian officers. Sampling gear was bongo net of MV Seafdec 2.
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Information of Sampling (Contd.)
Sampling track.
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Figure BL: 2.91 mm BL: 3.47 mm BL: 3.48 mm BL: 3.54 mm
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Figure BL: 3.82 mm BL: 4.02 mm BL: 4.03 mm BL: 4.45 mm
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Detail of Illustrated Specimen
TL: mm SL: 8.39 mm TL : mm BD : 4.0 mm ED : 1.2 mm SnL : 8.5 mm PAL : 5.0 mm Stage :post-flexion DF : 26 AF : 28 P1F : 13 P2F : -- PCR : 12 My : --
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Morphological Description
Body deep and compressed in moderated body shape. Tail pigment present in pre flexion period. Dorsal spine formed since pre flexion. There isn’t any pelvic fin ray. Only pelvic spines which forms as early as short bud. Body shape going elongated as its growth. BL: 2.91 mm TL: mm SL: 8.39 mm BL: 3.82 mm
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Similar Features with Other Family
Identify monacanthid larvae through its characteristic, e.g. compressed body with strongly coiled gut, pigment pattern, lack of pelvic fins, anterior position of the dorsal fin spine, and dermal spinules. Monacanthid has small melanophores (which there’re large melanophores of pomacentrids). Early dactylopterid larvae have pigment similar to that of monacanthids, but the former have extensive head spination lacking in the latter. Triacanthids and some monacanthids are very similar. The 1st spinules of triacanthids form on the preopercle, but they don’t form a raised tuft as in morph 1 monacanthids. Morph 1 monacanthids are more compresed than balistids, have earlier forming dorsal fin spines and body spinules, have a less conspicuous preopercular spinule tuft, are less heavily pigmented and most species have more myomeres.
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