Pallenopsis, Wilson, 1881

Cano-Sánchez, Esperanza & López-González, Pablo J., 2019, Two new species and new findings in the genus Pallenopsis (Pycnogonida: Pallenopsidae) with an updated identification key to Antarctic and Sub-Antarctic species, Zootaxa 4585 (3), pp. 517-530 : 527-528

Key to Antarctic and Sub-Antarctic species of Pallenopsis (adults)

1. Chela fingers curved, slender and leaving a gap proximally when closed.......................................... 2

1’. Chela fingers broad, wedge shaped and touching proximally when closed (fingers touching along their entire length or having a gap between them at mid-length)........................................................................ 6

2. Without or with small auxiliary claws (less than one-third of the main claw)....................................... 3

2’. With auxiliary claws (more than one-third of the main claw).................................................... 4

3. Claw longer than propodus. Without auxiliary claws..................................... P. macronyx Bouvier, 1911

3’. Claw subequal or shorter than propodus. With small auxiliary claws....................... P. longiseta Turpaeva, 1957

4. Dorsal series of distinct long forward curving setae on the three longer articles of the walking legs................................................................................................ P. meridionalis Hodgson, 1914 (1)

4’. Without these dorsal series of curved setae.................................................................. 5

5. Lateral processes about 1,5 times longer than their diameter. Chela immovable finger placed perpendicularly at half length of lateral edge palm.................................................................... P. lateralia Child, 1995

5’. Lateral processes as long as wide. Chela fingers (movable and immovable) placed distally on palm. P. villosa Hodgson, 1907

6. Trunk circular or discoidal in dorsal view. Lateral processes touching along most of their length...................... 23

6’. Trunk more slender. Lateral processes touching only proximally or not touching at all............................... 7

7. Without auxiliary claws............................................................. P. spicata Hodgson, 1915

7’. With auxiliary claws................................................................................... 8

8. Length trunk: length proboscis> 2.4.................................................. P. leiopus Pushkin, 1993

8’. Length trunk: length proboscis <2.4...................................................................... 9

9. Propodus with 5 small short heel spines................................................ P. lattina Pushkin, 1993 (2)

9’. Propodus with other configuration....................................................................... 10

10. Proboscis swollen at the middle (bottle-shaped)........................................... P. yepayekae Weis, 2014

10’. Proboscis not swollen at the middle (not bottle-shaped)....................................................... 11

11. Ratio propodus: claw length <1.3. Long setae on dorsal, lateral and ventral surface of walking legs........................................................................................................ P. pilosa ( Hoek, 1881)

11’. Ratio propodus: claw length> 1.3. No long setae on all surfaces of walking legs.................................. 12

12. Length of coxa 2 shorter than coxa 1 plus coxa 3. Proboscis narrow on anterior part, straight ventrally and concave dorsally .............................................................................. P. latefrontalis Pushkin, 1993

12’. Length of coxa 2 subequal or longer than coxa 1 plus coxa 3. Proboscis with other shape............................ 13

13. Lateral processes touching proximally (between second and third segment)....................................... 14

13’. Lateral processes not touching proximally (between second and third segment)....................................15

14. Length: width of propodus> 4...................................................... P. tumidula Loman, 1923 (3)

14’. Length: width of propodus <4.................................................... P. patagonica ( Hoek, 1881) (4)

15. Proboscis with second third gradually widening and distal third gradually narrowing.......... P. gurjanovi Pushkin, 1993

15’. Proboscis cylindrical (most of its length).................................................................. 16

16. Movable finger of chela without setose pad................................................................ 17

16’. Movable finger of chela with setose pad................................................................... 18

17. Walking legs with long setae arranged in rows....................................... P. vanhoeffeni Hodgson, 1915

17’. Walking legs with long setae not arranged in rows....................................... P. hodgsoni Gordon, 1938

18. Movable and immovable chela fingers well curved, on inner and external entire edges...... P. candidoi Mello-Leitao, 1949

18’. Movable and immovable chela fingers only slightly curved on external edges, but inner edges straight at least half their length................................................................................................... 19

19. Ratio claw: auxiliary claw length> 3............................................... P. buphtalmus Pushkin, 1993

19’. Ratio claw: auxiliary claw length <3..................................................................... 20

20. Lateral processes with distal tubercle................................................ P. hiemalis Hodgson, 1907 (4)

20’. Lateral processes without distal tubercle.................................................................. 21

21. Chela finger long; ratio fingers length: maximum width> 1.5.................................. P. kupei Clark, 1971

21’. Chela finger short; ratio fingers length: maximum width <1.5................................................. 22

22. Proboscis slightly widened at the middle and at the end. Ocular tubercle truncated at the tip..................................................................................................... P. boehmi Schimkewitsch, 1930 (5)

22’. Proboscis without any widening along its entire length. Ocular tubercle tip pointed..................... P. gracilis n.sp.

23. Chela fingers touching proximally when closed (having a gap between them at mid-length). Walking legs with simple long setae, setae without setules........................................................ P. obliqua ( Thomson, 1884)

23’. Chela fingers touching along their entire length when closed. Walking legs with long setae with setules.... P. rotunda n. sp.

(1) The original description of P. meridionalis Hodgson, 1914 did not provide information about the chela fingers morphology. Stock (1975) included this species in the subgenus Bathypallenopsis , for this reason we consider in this paper that P. meridionalis has fingers in agreement with the diagnostic character of this subgenus. The specimens described and illustrated by Pushkin (1975) as P. meridionalis , were later considered by the same author ( Pushkin, 1993) as P. patagonica . However, in this last paper, while also recognizing the validity of P. meridionalis as a separate species, this author used again the same illustration form his 1975 paper (see Pushkin 1993: 254).

(2) The original description of P. lattina provided by Pushkin (1993) (in Russian) is the only one available, but it is incomplete as this author did not illustrate it, and some characters were described insufficiently (e.g. the presence or absence of a setose pad is not indicated, the measurements of some walking leg articles are not detailed).

(3) According to Stock (1957) who illustrated the syntypes of this species, P. tumidula differs from P. patagonica by its slender coxa 2 and propodus, as well as the presence of plumose spines on the coxae. Munilla (1991) reported a specimen of P. tumidula , but only provided information about its measurements.

(4) This is a frequently reported Antarctic Pallenopsis species. Several species have been synonymised with P. patagonica over the years, such as P. glabra , P. meridionalis , P. hiemalis , and P. moebiusi . Calman (1915), Gordon (1932; 1944), Pushkin (1975; 1993), and Chid (1995) discussed the wide morphological variations of this species, such as compactness of the body, size of the 4th trunk segment, propodus armature, the oviger structure, or the appearance of the cement gland in males. Recently, Weis et al. (2014) and Harder et al. (2016) using molecular analyses considered P. patagonica as a complex of species, but they did not assign morphological characters to each clade. Here in this study, we consider P. hiemalis and P. meridionalis valid species, as previously mentioned.

(5) Based on the re-description by Stock (1973b).