Tanystylum, Miers, 1879

León-Espinosa, Angel De, León-Gonzalez, Jesus Angel De & Gómez-Gutiérrez, Jaime, 2021, Pycnogonids from marine docks located along the west coast of the Gulf of California, Mexico, Zootaxa 4938 (2), pp. 151-195: 165-168

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Tanystylum  sp.

( Figs. 6View FIGURE 6 A–E; 7 A–I)

Material examined. Two specimens: 1³, (UANL-FCB-PYCNO-0061), FONATUR, Santa Rosalía, Baja California Sur , Mexico, 27°20 ́13 ́N, -112°15 ́47 ́W, 11/15/2013; 1J, (UANL-FCB-PYCNO-0062), Cantamar , Bahía de La Paz , Baja California Sur, Mexico, 24°16´44´´N, - 110°19´51´´W, 06/26/2017 ( Fig. 1View FIGURE 1)GoogleMaps  .

Description. Trunk discoidal, all segments completely fused, segmentation lines not observed. Lateral processes short, touching, each with a median tubercle and a pair of setae on the distal end. Ocular tubercle a low truncate cone, longer than wide, with four eyes, a small posterior knob ( Fig. 6View FIGURE 6 A–B; Fig. 7View FIGURE 7 C–E). Abdomen long elevated slightly upward, four short setae on distal part, ending in two conical processes ( Fig. 6View FIGURE 6 A–B, Fig. 7 C, IView FIGURE 7). Long, piriform proboscis, directed anteriorly ( Fig. 6View FIGURE 6 A–B; Fig. 7View FIGURE 7 A–C), mouth has triangular lips with a band of small setae along each lip ( Fig. 7View FIGURE 7 A–B).

Chelifores short, biarticulate, scape long with a dorsal and a latero-distal seta; chela non-functional, ¼ the length of the scape, rounded distally ( Fig. 6 AView FIGURE 6; Fig. 7View FIGURE 7 C–D).

Palp with five articles, longer than the proboscis. First article long, with two setae, a dorso-distal and a midlateral. Second article approximately 1/3 the length of article 1, glabrous. The third article with a middle-dorsal seta, five ventral setae and a latero-distal seta. Fourth article is the smallest, with a mid-dorsal seta, a dorso-distal seta, and a mid-ventral seta. Fifth article slightly shorter than first one and covered anteriorly with lateral and ventral setae ( Fig. 6 CView FIGURE 6; Fig. 7 FView FIGURE 7).

Oviger with six articles. First article glabrous. Second article ½ the size of the first one, with a dorso-distal seta. Third article 1.3 times longer than first one, with a dorso-distal seta. Fourth article longest, 1.5 times longer than the first one, with a middle-dorsal seta. Fifth article shorter, ½ the size of first one, with a dorso-proximal and a dorso-distal seta. Sixth article bifurcate, with four long setae in the dorsal part, and two distal setae on ventral part ( Fig. 6 EView FIGURE 6).

Thick legs. Coxa 1 short, with a dorso-distal seta. Coxa 2 longer than coxa 1 and 3 together, with a group of twelve lateral setae. Coxa 3 with a mid-lateral seta and a row of five latero-distal setae. Femur widened distally, covered by several groups of setae, those of dorsal surface longer than the others. Tibia 1 with three dorsal setae, longest article. Tibia 1 slightly larger than tibia 2, with seven dorsal setae and two ventro-distal setae. Tarsus small, with a dorso-distal seta. Propodus with a row of eight dorsal spines, no heel spines, a row of six ventral sole spines and a row of four lateral setae. Main claw strong, slightly curved; auxiliaries also feebly curved, ¾ length of main claw ( Fig. 6 DView FIGURE 6; Fig. 7View FIGURE 7 G–H).

The immature specimen presents well-developed chelifores, with two articles, the scape longest, the chelae with mobile finger larger than immobile one. Oviger fully developed, with six articles, last one bifurcated. The rest of the characters are similar to the mature specimen.

Measurements of the illustrated specimen (mm). Trunk: 0.6 long from the insertion of chelifore to insertion of the fourth pair of lateral processes, 0.5 wide across the second pair of lateral processes; proboscis length 0.45, 0.2 wide.

Third leg: Coxa 1, 0.25; coxa 2, 0.42; coxa 3, 0.22; femur, 0.64; tibia 1, 0.8; tibia 2, 0.74; tarsus, 0.06; propodus, 0.48; main claw, 0.15.

Oviger: 1) 0.14; 2) 0.08; 3) 0.17; 4) 0.2; 5) 0.08; 6) 0.7.

Distribution. Tanystylum  sp. was collected from two marinas: Cantamar in Bahía de La Paz and FONATUR in Santa Rosalía, Baja California Sur, Mexico.

Remarks. The genus Tanystylum  includes 48 nominal species worldwide. Five species have been reported in the Eastern Tropical Pacific: Tanystylum californicum Hilton, 1939  from California; T. cinctum Child 1992  from Ecuador; Tanystylum distinctum Child & Hedgpeth, 1971  from Ecuador, Galapagos Islands and Chile; Tanystylum dowi Child, 1979  from the Pacific coast of Panama; Tanystylum duospinum Hilton, 1939  , from California, Tanystylum intermedium Cole, 1904  from California, Mexican Pacific, Pacific Panama, Ecuador, Galapagos Islands, Perú and Chile; Tanystylum isthmiacum Stock, 1955  from the Gulf of California and the Mexican Pacific, Costa Rica, Panama, and Ecuador; Tanystylum malpelensis Child, 1979  from the Pacific coast of Colombia and the Galapagos Islands, and Tanystylum occidentale ( Cole, 1904)  from Pacific Grove, California.

The two specimens included in the present study are morphologically distinct from all other previously described Tanystylum  species and may be new. This unidentified species was readily distinguished from all other Eastern Pacific members of Tanystylum  by the 6-articled oviger, the last article bilobed and Y-shaped. Three of the above Tanystylum  species ( T. duospinum  , T. dowi  , and T. isthmiacum  ) have palps with 5 articles similar to Tanystylum  sp., the others have 4, 6 and 7 palp articles, respectively. The Tanystylum  sp. specimens were distinct from all the other specimens in the present study in the shape of the ocular tubercle, the structures associated with the lateral process, and the size of the auxiliary claws. For instance, the ocular tubercle of T. duospinum  is triangular, wide at the base, with a sharp point on top; the lateral processes are unadorned, lacking accessory structures such as tubercles or setae; and the auxiliary claws are minute, less than ¼ length of the main claw. The ocular tubercle of T. dowi  possesses an apical papillary structure, lateral processes with rounded corners and two lateral tubercles, each armed with a seta, and the auxiliary claws about ½ the length of main claw. The ocular tubercle of T. isthmiacum  is conical, without a papillary structure, lateral processes with a middle anterior triangular tubercle armed with an apical seta, and the auxiliary claws are ½ length of main claw.