Anoplodactylus ganchiformis, Lucena & Christoffersen, 2018

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 : 383-385

Anoplodactylus ganchiformis sp.nov. ( Figures 4 a−4j)

Material examined: Ceará: Holotype − ( UFPB. PYC–242) 1 ♂, Jericoacoara, intertidal, 11 Aug 2014, coll. R.A. Lucena and J. Prata . Paratypes − ( UFPB.PYC–217) 11 ♂♂, 6 ♀♀ and 24 juveniles, Jericoacoara, intertidal, same collection data as holotype . Further material − ( UFPB.PYC–243) 1 ♂, 2 ♀♀ and 1 juvenile, Jericoacoara , intertidal in hydrozoan, 11 Aug. 2014, coll. R.A. Lucena and J. Prata. Maranhão: ( UFPB.PYB–222) 3 ♂♂, 2 ♀♀ and 10 juveniles, Praia do Meio, 21 Mar. 2015, inertidal, coll. R.A. Lucena, J. Prata and J.P. de Araújo .

Diagnosis: Segmentation absent between segments 3 and 4. Lateral processes separated by half their diameter, with a dorsal triangular tubercle and a small lateral seta. Processes 3 and 4 contiguous. Third article of the oviger with a small hook directed backwards, near the base. Propodus with 8 spines on heel, 2 large, apical, and 6 directed towards sole. Distal region of sole with a very small cutting lamina. Female with 2 alar processes at the base of the proboscis, formed by four lobules, each lobule formed by small teeth on distal margin. Palp reduced to a small cylindrical tubercle present only in females.

Description (Male): Trunk elongate, with incomplete segmentation, absent between segments 3 and 4 ( Figures 4a–4b). Shoulders with a small rounded tubercle. Proboscis cylindrical, elongate ( Figure 4c). Lateral processes separated by half their diameter, with a triangular dorsal tubercle, and a small lateral seta. Processes 3 and 4 contiguous. Ocular tubercle conical, elongate, eyes well pigmented. Abdomen located between processes 3 and 4, completely erect and large.

Cheliphores elongate, with uniarticulate scapus, very close at base but gradually becoming distanced ( Figure 4e); with few setae that are more concentrated in distal region. Chela robust, smaller than fingers. Fingers elongate; fixed finger with seta near base; movable finger with setae on external margin. Oviger with 6 articles ( Figure 4f). First article robust and without setae. Second and third articles almost of same size, the third being only slightly bigger, third article with a small hook directed backwards, near the base. Fourth and fifth articles robust; sixth rounded. Fifth and sixth articles with many setae.

Legs elongate, with small setae ( Figure 4g). Coxae 1 and 3 very small, together almost of the same size as the second. Coxa 2 with a very elongate spur on legs 3 and 4 ( Figure 3h). Femur elongate, with 3 small distal tubercles. Tube of cement gland short, forming a sharp angle with the femur, with median region of tube directed forwards; located in middle region of femur. Tibiae 1 and 2 of the same size, with elongate setae on dorso-distal region. Tarsum trapezoid, with dorsal setae and ventral setae with a fine spine. Propodus with 8 spines on heel, the 2 apical ones large and the 6 remaining ones directed towards the sole ( Figure 4i). Sole with 8 small spines along its extent, marginalized by small setae. Distal region of sole with a very small cutting lamina. Main claw with three-fourths of length of propodus. Main claw extremely reduced.

Description (Female): Almost equal to male, differing by owning two alar processes at base of proboscis. Alar processes formed by 4 lobes, each lobe formed by small teeth of distal margin. Palp reduced to a small cylindrical tubercle present only in females.

Juveniles: With the 2 lateral processes fused. There is only 1 spine on heel.

Measurements (Holotype – in mm): Length of trunk, 1.70; width of trunk (above segment 2), 1.23; length of abdomen, 0.53; length of proboscis, 0.76; length of cheliphere, 1.02; third leg – coxa 1, 0.25; coxa 2, 0.70; coxa 3, 0.39; femur, 1.28; tibia 1, 1.04; tibia 2, 1.09; tarsum, 0.17; propodus, 0.20; main claw, 0.44; auxiliary claws, 0.05.

Distribution: Brazil (Ceará and Maranhão).

Type locality: Jericoacoara , Ceará, Brazil .

Etymology: The specific epithet “ ganchiformis ” refers to the shape of the hook on the third article of the oviger.

Depth: Mesolittoral.

Remarks: Like Anoplodactylus ricardoi , this species belongs to the group A. californicus-digitatus . This species is easier to distinguish from the remaining species. Its large triangular tubercle on the lateral processes, the very elongate spur on the coxa 2 of legs 3 and 4, the basal constriction of the third article, forming a hook directed backwards, the three tubercles on the distal region of the femur, and the alar process formed by 3 or 4 dentate lobules on the proboscis of the female make this species unique.

As Anoplodactylus ricardoi , this species is also close to A. californicus and A. stictus due to its body pattern. In addition to the above-mentioned characters, this species is more elongate than the remaining ones and has the lateral processes 3 and 4 almost contiguous, while the remaining species are more robust and the lateral processes are more separated, at least half as much as their own diameter.

Of the three species ( Anoplodactylus ricardoi , A. californicus and A. stictus ), A. stictus is the closest for having tubercles on the lateral processes. However, the male of Anoplodactylus ganchiformis sp. nov. has an abdomen that is almost twice as long as the ocular peduncle and becomes distally narrow (it is short in A. stictus ). The lateral processes have an elongate, conical tubercle (short in A. stictus ). Lateral processes 3 and 4 are almost contiguous, while the remaining species are separated by their diameter (they are close only basally in A. stictus ). The ventral spur of coxa 2 of the legs 3 and 4 are extremely long, that of leg 4 being quite robust (it is short in A. stictus ). There are 3 tubercles on the dorsal region of the femur, the median one quite long (only the median tubercle is present in A. stictus ). There is a small hook on the third article of the oviger (no such structure in A. stictus ). Regarding the female, both species have the same pattern of ornamentation and rudimentary palps. A. stictus has a small tubercle, which is cylindrical in Anoplodactylus ganchiformis .

We observed that the hook of the oviger was variable. It may be well made of or represented by a mere tubercle slightly directed backwards. Maybe this ornamentation as well as the tubercle of the femur are dependent on the size of the animal, as juveniles have these structures reduced in size and development.