Cidaridae頭帕科-Prionocidaris鋸頭帕屬的診斷特徵

Cidaridae頭帕科-Prionocidaris鋸頭帕屬的診斷特徵

 

英國自然歷史博物館(The Natural History Museum)針對Cidaridae頭帕科之Prionocidaris鋸頭帕屬的診斷特徵，列出以下9點特性以供參考：

Prionocidaris    Agassiz, 1863

l          Test relatively tall; moderately thin and fragile.

 

l          Apical disc 40-50% test diameter; monocyclic. Genital plates all similar in size. All plates covered in scattered tubercles.

l          Interambulacra with up to 12 plates in a series. Primary tubercles perforate and non-crenulate (the most adapical tubercles may have a trace of crenulation on their adapical side). Areoles ovate; incised; separated by scrobicular circles except immediately beside the peristome.

l          Scrobicular tubercles hardly differentiated. Extrascrobicular zones not extensive; densely covered in heterogeneous secondary tubercles and granules.

l          No sutural pits or furrows.

l          Ambulacra weakly sinuous. Pore zones not incised; pore-pairs subconjugate to conjugate, the two pores usually widely separated. Perradial zone fully tuberculate, with marginal series of contiguous primary tubercles and inner zone of smaller secondary tubercles.

l          Peristome a little smaller than apical disc. Interradial plate series not quite reaching the peristome; ambulacral plates uniserial in each column.

l          Primary spines long and relatively slender; tapering or ending in small crown. Collar and neck short; shaft ornamented in rows of modest thorns; surface between thorns covered in fine cortical hairs.

l          Secondary spines flattened but not adpressed.