Recent Aedvances in Cephalopod Systematics

Transcription

1 Recent Aedvances in Cephalopod Systematics Kotaro TSUCHIYA Lab. Invertebrate Zoology

2 What the Cephalopoda

3

4 Paleozoic Mesozoic Neozoic Million yr

5 Squid Cuttlefish Vampire squid Octopus Bobtil squid

6 Molluscan Characters

7 Current Classification of Mollusca Phylum Mollusca Class Solenogastres Class Caudofoveata Eumollusca Class Polyplacophora Conchifera Class Monoplacophora Ganglioneura Viscelloconcha Class Gastropoda Class Cephalopoda Diasoma Class Scaphopoda Class Bivalvia

8 Gastropoda Viscelloconcha Bivalvia Diasoma Scaphopoda Cephalopoda

9 Cephalopod Characteristic A funnel derived from the molluscan foot or the molluscan neck region (Shigeno et al., 2007). Circumoral arms that are derived from the molluscan head (J.Z. Young, 1965) or the molluscan foot (Shigeno et al., 2007). Chitinous beaks. Image-forming eyes.

10 Cephalopod Characteristic A funnel derived from the molluscan foot or the molluscan neck region (Shigeno et al., 2007).

11 Cephalopod Characteristic Circumoral arms that are derived from the molluscan head (J.Z. Young, 1965) or the molluscan foot (Shigeno et al., 2007).

12 Cephalopod Characteristic Chitinous beaks. Upper beak Buccal mass

13 Cephalopod Characteristic Image-forming eyes.

14 Ontogeny & Phylogeny Spiral cleavage - Discoidal cleavage Larval development - Direct development Lecithophora or Meloblastea Fischer, 1880 As Subphylum for CEPHALOPODA trochophore Gastropoda veliger Cephalopoda

15 Squid and Octopus Decapodiformes and Octopodiformes What s difference? Sucker morphology Buccal rappet existence

16 Squid and Octopus What s difference? Modification of the fourth pair of arms as tentacles

17 Current Classification of Cephalopoda Based on morphological character

18 Octopoda Leach, 1818 Cirrata Grimpe, 1916 Incirrata Grimpe, 1916 Vampyromorpha Robson, 1929

19

20 16s rdna 12s rdna CO I

21 Mitochondria genome structure

22 Clarke (1988) Morphological base

23 Order Teuthoidea Divergent group in genus level 28 Families 71Genera Most of the families are oceanic, mesopelagic

24 Oegopsida - Myopsida

25 Family Chtenipterygidae - comb-fin squid with suckers on the buccal membrane. without carpal locking-apparatus on tentacles. with branchial canals in gills.

26 Family Idiosepiidae - pygmy squid Gladius (shell) rudimental but present with an adhesive organ on the dorsal surface of the mantle Idiosepius pygmaeus (6-8mm ML)

27 Family Australiteuthidae Lu, 2005 Myopsid eye Spritted fins Feather-shaped chitinous gladius Australiteuthis aldrichi Lu, 2005 (<30mm ML)

28 Morphological comparisons of the major taxa within the Decapodiformes Cornea canal Branchial Buccal support circular Sucker pocket Tentacle Interstellate connective sucker muscle Oegopsida No Yes No No No Yes Bathyteuthoidea No Yes Yes No Yes Yes Myopsida Yes Yes Yes/No Yes Yes Yes Idiosepiidae Yes No No No Yes? Spirulidae No No No No Yes No Sepioidea Yes No Yes/No Yes Yes No

29 Recent Systematic Hypothesis Molecular base

30 Morecular Analysis (Akasaki et al. 2006) mtdna genome structure

31 Hypothesis from Morecular Analysis (Akasaki et al. 2006) mtdna genome structure

32 Hypothesis from Morphological and Molecular complex Analysis result 101 morphological characters mt cytochrom c oxydase subunit I ; nuclear 18S rdna; D3 expansion fragment of 28S rdna, Histon H3

33 Classification Updated Young (2008)

34

35 Species-level Taxonomy Only 700 species are known from World Ocean

36 Cryptic Speciation Coastal species (Loliginids, Sepiids) Western Australia Triantafillos et al. (2005) Japan Izuka et al. (1996) Sepioteuthis lessoniana

37 Deep-sea Squids - still unexplored field Nektonic species - net avoidance Difficult to catch adult specimens by sampling gear Still unkown the mature, largest size in most of deep-sea species Life cycle, life history

38 Octopus - Labyrinth of Taxonomy Scarce of hard tissue in octopus body Absence of stable key taxonomic character Need to evaluate useful taxonomical information from living animals