The Echinoid Directory

Pachechinus A. Agassiz, 1872, p. 159, 194

[=Cryptopora A. Agassiz, 1872, p. 159, 177 (objective); Pachycentrotus H.L. Clark, 1912, p. 349 (objective) ]

Diagnostic Features	Test circular in outline; subconical in profile. Apical disc hemicyclic with ocular plates I and V always insert and rarely with ocular plates II and IV also insert. Ambulacra mostly polygeminate, with four pore-pairs to a compound plate, arranged in an oblique line. Some trigeminate plates intersperced, especially adorally. Inner pore-pair forming a vertical series separated from the rest. Interambulacral plates with primary tubercle flanked by one or more lateral secondary tubercles almost as large; forming horizontal rows. Plates densely tuberculate. Buccal notches sharply defined. Spines fine and short (less than 0.25 test diameter). Globiferous pedicellariae with tubular blade and single lateral tooth.
Distribution	Recent; South Australia, littoral to 70 m.
Name gender	masculine
Type	Sphaerechinus australiae A. Agassiz, 1872, by ICZN 4th ed. Art. 67.12.
Species Included	P. australiae (A. Agassiz, 1872); Recent, Australia P. bajulus (Dartnall, 1972); Recent, Australia
Classification and/or Status	Camarodonta; Echinoida; Echinometridae. A junior subjective synonym of Heliocidaris.
Remarks	Close to Evechinus from which it differs in having four rather than three pore-pairs to a compound plate. Originally published as a synonym (of Sphaerechinus). According to ICZN rules, Lambert & Thiery's (1909-24: p. 250) treatment of Pachechinus makes it an available name (see ICZN 4th ed. Art. 11.6.1.) Agassiz, A. 1872-1874. Revision of the Echini. Memoirs of the Museum of Comparative Zoology at Harvard College, 3: pts. 1-2: i-xii, 1-378, pls 1-49 (1872); pt. 3: 379-628 +1, pls 50-77 (1873); pt. 4: 629-762, pls 78-94 (1874).