Anoplodactylus stictus Marcus, 1940

Lucena, Rudá Amorim & Christoffersen, Martin Lindsey, 2018, Anoplodactylus (Pycnogonida: Phoxichilidiidae) from Brazil, new records and two new species, Turkish Journal of Zoology 42 (4), pp. 372-388 : 380-381

Anoplodactylus stictus Marcus, 1940

Anoplodactylus stictus Marcus, 1940: 65-68 , plate VI, figures 7e–7f, plate VII, figures 7a–7d; Sawaya, 1945: 231- 234, figures 1 and 2; Bremec et al., 1986: 36-37, figures 7 and 8; Stock, 1992: 134, figure 62.

Material examined: Rio Grande do Norte: ( UFPB. PYC–112) 1 ♀, Ponta do Mel , Brazil, 23 Jun. 1982, coll. A.I. Kanagawa. Ceará: ( UFPB.PYC–111) 1 ♂ and 1 ♀, Ponta Grossa, 24 Jun. 1982, coll. M.L. Christoffersen and A.I. Kanagawa.

Diagnosis: Trunk elongate with segmentation between segments 3 and 4, or segmentation absent. Lateral processes separated by less than their diameter, with 1 or 2 hairs and a rounded dorsal tubercle. Ocular tubercle elongate. Proboscis of female with a cordiform protuberance. Scapus and palm with few setae that are concentrated at the basis of the movable finger. Third article of oviger with a pseudo-segmental fold. Legs long. Coxa 2 with a small dorso-median tubercle. Femur with a distal tubercle and a long terminal seta. Tube of cement gland short. Tibiae 1 and 2 with a long distal seta. Heel of propodus with 1 or 2 spines. Sole with 6 to 10 spines in proximal region, and a cutting lamina in distal region. Auxiliary claws varying in size within the same individual.

Distribution: Brazil (off Santa Catarina, Paraná, São Paulo, Rio de Janeiro, Espírito Santo, Rio Grande do Norte and Ceará), Argentina ( Marcus, 1940; Bremec et al., 1986; Stock, 1992).

Depth: Up to 250 m deep.

Remarks: As described by Marcus (1940), A. stictus has nondenteate alar processes on the proboscis of the female, a tubercle on the lateral processes of the male, and a cutting lamina on the distal third of the propodal sole, which is different from A. californicus , the closest known species.

We did not observe the presence of a cutting lamina on the sole of the propodus, this being the only important difference detected in relation to the original description. We also observed that individuals of A. californicus tended to be larger than individuals of A. stictus , a character hypothesized by Marcus (1940) as diagnostic to differentiate the two species.

An association of A. stictus with the hydrozoan Tubularia crocea (Agassiz, 1862) was recorded ( Genzano, 2002), probably representing a predator ( Varoli, 1994). However, they were also recorded as parasites of a new hydrozoan species of the genus Podocorina Sars, 1846 , an association established by chance in an incrusting community of experimental plates in Paranaguá, Paraná ( Bettim and Haddad, 2013). According to Marcus (1940), A. stictus is the closest to A. californicus but may be distinguished mainly by the larger size, by the presence of a remnant of the propodus in A. californicus , by the presence of a cutting lamina in the propodal sole in A. stictus , and by a small protuberance on the movable finger of the chela ( Stock, 1992).

This species is known to exist in shallow waters, most species occurring along the upper continental platform in Brazil ( Marcus, 1940; Sawaya, 1945) and northern Argentina ( Stock, 1992).

In the specimens examined by us, the male had a more elongate and conical ocular peduncule than the female. Segmentation between segments 3 and 4 was almost imperceptible and, in some cases, completely absent. On the coxae 1, there were small lateral projections, each with a terminal seta, more conspicuous in males. Some females and juveniles had small tubercles on the lateral processes, more developed in young specimens. According to Marcus (1940), these were only present in males. Vestiges of auxiliary claws were not observed in any of the four examined specimens.

Here we recorded this species for the first time in northeastern Brazil, in the States of Rio Grande do Norte and Ceará.