Benson 1966 - Acrobotrys teralans

Smooth cephalis with two lobes separated by a constriction coincident with a thin rib--a smaller, rounded, ventral lobe, and a larger dorsal lobe.A smooth, subcylindrical thorax with slightly constricted mouth separated from both cephalic lobes by a constriction coincident with a thin rib.A ventral latticed tube present in all specimens on the upper ventral face of the thorax. In a few specimens one or two additional latticed tubes present, one coincident with the short apical spine, the other ascending dorsally in the sagittal plane from the upper surface of the dorsal cephalic lobe. Pores of cephalic lobes and thorax similar, circular to subcircular, small, subequal, but irregularly arranged. Internal structure shown in text-fig. 21B.The ribs outlining the ventral lobe correspond to the apical-lateral arches and the ventral arch. The median bar short, underlies the ventral lobe. Apical bar an internal columella which extends as a rib along the ventral edge of the dorsal lobe and projects as a short, apical spine. Vertical bar terminates near the proximal portion of the ventral tube. The dorsal and primary lateral bars pierce the thoracic wall and extend as short spines that are joined by a lattice to the wall of the thorax. Secondary lateral bars terminate at the constriction separating the dorsal cephaliclobe from the thorax.

Measurements: based on 5 specimens from stations 191 and 192: length of dorsal lobe 37-50 m, of ventral lobe (measured from median bar) 21-25 µm, of thorax 37-58 µm; breadth of dorsal lobe 22-30 µm, of ventral lobe 18-20 µm, of thorax 53-59 µm, length of ventral tube 6-9 µm, diameter 6-9 µm; length of dorsal and primary lateral spines 12-33 µm.

Remarks: This species is rare in the Gulf sediments; therefore, its complete range of variation was not determined. Because the number of latticed tubes is variable within this species, this character should not be used in defining the species. Whether or not the thoracic mouth is closed by a lattice could not be determined from the few specimens studied. None of the species of Acrobotrys illustrated by Haeckel conform to the Gulf species in shape and size of cephalic lobes. In number of tubes A. diso1enia Haeckel (1887, p. 1114, Pl. 96, fig. 10) is similar to the Gulf species; however, Haeckel indicates a third lobe from which originates the ventral tube, but in the Gulf specimens the internal primary lateral bars appear to separate a third lobe but actually do not. Haeckel may have misinterpreted the third lobe. Unless Haeckel's type material can be studied, identification of the Gulf species as A. disolenia is not positive.

Distribution: This species is rare in the Gulf but occurs as far north as stations 191 and 192.Besides these stations it is present at stations 56, 60, 93, 106, 115, 136, and 151.Its presence in the northern half of the Gulf may be related to upwelling there. Its very rare occurrence and spotty distribution, however, indicates its lack of great affinity for Gulf waters. Haeckel reported Acrobotrys disolenia from the central Pacific at Challengerstations 265-274.Because identification of the Gulf species is not positive, analysis of its world-wide distribution cannot be made. \ From: Benson, 1966, p. 339-341; pl. 23, figs. 13-14; text-fig. 21:Acrobotrys cf. disolenia Haeckel?Acrobotrys disolenia Haeckel, 1887, Challenger Rept., Zool., vol. 18, p. 1114, Pl. 96, fig. 10.

References: