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Acrobotrys cribosa (Popofsky, 1913)

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Benson, 1966, p. 342-344; pl. 23, fig. 15; text-fig. 22:

Acrobotrissa cribosa Popofsky

Acrobotrissa cribosa Popofsky, 1913, Deutsche SŘdpolar-Exped., vol.14, p. 322, text fig. 29.

A small rounded cephalis, partly within test cavity, surrounded by four lobes--a lateral triangular lobe on either side of it, a small ventral lobe with a latticed ventral tube (in most specimens tube not distinguishable), and a large, inflated dorsal lobe (text-fig. 22). All lobes separated by constriction coincident with ribs. A small, subcylindrical thorax with a slightly constricted mouth is present; a hyaline peristome present in several specimens. Surface of test smooth except for a few short thorns on the rim of the ventral tube. Pores of cephalic lobes and thorax of similar size, about as wide as the intervening bars, circular, subregularly arranged. Internal structure illustrated in text-fig. 22A. A distinct collar ring with cardinal and cervical pores present at base of latticed cephalis but separated from cephalis by large pores. Primary lateral bars extend as short ribs in the thoracic wall and terminate in short spines. Dorsal bar terminates in a short spine arising from the constriction between the dorsal cephalic lobe and the thorax, whereas the secondary lateral bars terminate at this constriction. A long (35 Ám), thin, crooked axial spine present in a few tests. A short, thin, conical vertical spine present within the test cavity. Apical bar free above median bar, becomes a dorsal rib of the latticed cephalis above this, and extends as an internal columella within the dorsal cephalic lobe but pierces this lobe and continues as a short, thin, conical apical spine.

Measurements; based on 5 specimens from stations 60, 191, and 192: length of test 98-108 Ám, of dorsal lobe 34-80 Ám, of cephalis 21-25 Ám; breadth of dorsal lobe 26-46 Ám, of thorax 43-66 Ám; length of apical spine 6-22 Ám, of dorsal and primary lateral spine 6-10 Ám.

Remarks. This species is identical with Popofsky's (1913, text fig. 29) illustration of Acrobotrissa cribosa. It is similar to Botryopyle dictyocephalus Haeckel (1887, p. 1113, Pl. 96, fig. 6) but has a ventral tube. Investigation of Haeckel's type material of this species may reveal that it is conspecific with A. cribosa Popofsky.

Distribution. This species is rare in the Gulf with more general occurrence in the southern half of the Gulf than in the northern half. In the southern Gulf it is present at stations 27, 34, 46, 56, 60, 71, 81, 92, and 93. In the northern Gulf it is present only at stations 191 and 192, both located within the diatomite facies. Its absence nearshore and its general occurrence in the southern Gulf indicates its affinity for oceanic waters. Its presence in the northern Gulf may be related to upwelling. Its absence between these two regions of the Gulf may be explained by its generally rare occurrence in the Gulf. If more stations were sampled its presence in this region may be revealed.
Popofsky (1913, p. 322) reported A. cribosa from the tropical Atlantic. It has not been reported from high latitudes and, therefore, is cosmopolitan in tropical seas.
Benson 1966


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