Munida gracilis Henderson, 1885

McCallum, Anna W., Ahyong, Shane T. & Andreakis, Nikos, 2021, New species of squat lobsters of the genus Munida from Australia, Memoirs of Museum Victoria 80, pp. 113-152 : 142-143

Munida gracilis Henderson, 1885

Figure 18

Munida gracilis Henderson, 1885: 412 (type locality: New Zealand, 38° 50' S, 169° 20' E). — Baba et al., 2008: 97. — Yaldwyn and Webber, 2011: 212. — Yan et al. 2020: 2, tab. 1.

Munida chydaea Ahyong and Poore,2004:24 , fig.4 (type locality: east of Brush Island, New South Wales, Australia). — Poore, 2004: 234, fig. 64b. — Baba, 2005: 260. Syn. nov.

Munida disgrega Baba, 2005: 103 , figs 40, 41 (east of Victoria, Australia). — Poore et al., 2008: 19. — McEnnulty et al., 2011: app. 1. Syn. nov.

Material examined. South Australia: SAM C7658 , 1 ovigerous female (cl 32.3 mm, pcl 18.5 mm), 1 damaged specimen (cl 18.5 mm, pcl 10.6 mm), Great Australian Bight, 33° 27.09' S, 130° 41.19' E, 500 m, BPZ 2010/500, 2010 .

Western Australia: NMV J55107 , 2 females (cl 24.8 mm, pcl 13.7 mm; cl 26.1 mm, pcl 15.5 mm), 3 males (cl 20.6 mm, pcl 11.2 mm to cl 21.9 mm, pcl 12.1 mm), Bald Island , 35° 14.022' S, 118° 39.84' E to 35° 13.674' S, 118° 40.5' E, 710–728 m, SS10/2005/32, 2005 ; NMV J55106 , 6 females (cl 11.4 mm, pcl 6.3 mm to cl 25.4 mm, pcl 14.3 mm), 10 males (cl 12.4 mm, pcl 7.4 mm to cl 24.0 mm, pcl 13.6 mm), Bald Island , 35° 14.022' S, 118° 39.84' E to 35° 13.674' S, 118° 40.5' E, 710–728 m, SS10/2005/32, 23 November 2005 ; NMV J55083 , 3 males (cl 27.9 mm, pcl 19.5 mm to cl 47.8 mm, pcl 34.9 mm), Pt Hillier , 35° 22.902' S, 117° 12.42' E to 35° 22.902' S, 117° 12.42' E, 539 m, SS10/2005/19, 2005 ; NMV J55080 , 1 female (pcl 7.9 mm), Albany , 35° 22.29' S, 118° 19.98' E to 35° 22.644' S, 118° 19.26' E, 685–695 m, SS10/2005/27, 2005 ; NMV J55084 , 16 females (cl 20.9 mm, pcl 11.9 mm to cl 36.6 mm, pcl 19.6 mm), 19 males (cl 14.3 mm, pcl 9.0 mm to cl 30.2 mm, pcl 17.9 mm), Albany , 35° 22.14' S, 118° 20.1' E to 35° 22.518' S, 118° 19.32' E, 676–680 m, SS10/2005/29, 2005 ; NMV J55082 , 1 female (cl 9.1 mm, pcl 7.0 mm), 2 males (cl 17.4 mm, pcl 7.8 mm; cl 15.1 mm, pcl 9.9 mm), Bald Island , 35° 12.81' S, 118° 39.06' E to 35° 12.24' S, 118° 40.14' E, 408–431 m, SS10/2005/34, 2005 .

New Zealand: NIWA 53772 , 1 female (cl 23.3 mm, pcl 15.8 mm), 44° 09.47' S, 174° 33.32' W to 44° 09.48' S, 174° 33.56' W, 520–650 m, TAN0905/103, 26 June 2009 ; NIWA 54087 , 1 ovigerous female (cl 21.0 mm, pcl 12.2 mm), Diamondhead Peak B, Andes Seamounts, 44° 08.97' S, 174° 45.41' W to 44° 09.02' S, 174° 45.63' W, 519–609 m, TAN0905/113, 27 June 2009 ; NIWA 54108 , 1 female (cl 24.4 mm, pcl 13.9 mm), Diamondhead Peak B, Andes Seamounts, 44° 08.99' S, 174° 46.09'W to 44° 09.01'S, 174° 46.3' W, 830–900 m, TAN0905/114, 27 June 2009 ; NIWA 63655 , 4 males (pcl 5.4–7.7 mm), Site 3a seamount, Hikurangi Margin, 41° 19.16'S, 176° 11.84' E to 41° 19.28'S, 176° 11.53' E, 495 m, TAN1004/66, 21 April 2010 .

Genetic data. CO1 and 16S; see Table 1.

Remarks. Munida gracilis is a common species in New Zealand, usually from depths of 300–600 m with a recorded range of about 100–1200 m (Yan et al., 2020), that is morphologically closest to the Australian Munida chydaea Ahyong and Poore, 2004 . COI sequences of specimens corresponding to Munida chydaea Ahyong and Poore, 2004 , from south-western Australia, however, were only 0.9–1.0% divergent from M. gracilis from New Zealand and 0.2% divergent for 16S. This low level of sequence divergence led us to further examine the morphological distinctions between M. gracilis and M. chydaea . Ahyong and Poore (2004) distinguished the two species based on the number of anterior

A

B

South-west Australia

Tasmania

F

G

New Zealand spines on abdominal somite 3 (1 or 2 spines in M. chydaea ; 4 spines in M. gracilis ), the length of the unarmed flexor margin of the P2 dactyli (distal one-quarter in M. chydaea versus distal one-third in M. gracilis ), spinules on the outer margin of antennal articles 3 and 4 in M. chydaea (absent in M. gracilis ) and more numerous transverse abdominal striae in M. chydaea . Our comparisons between new Australian and New Zealand specimens, however, failed to identify consistent distinguishing features. Although the many specimens examined by Ahyong and Poore (2004), primarily from from eastern Australia, were consistent in the aforementioned features, specimens examined herein from southern Australia (Tasmania, South Australia and Western Australia) and New Zealand exhibit morphological overlap. Thus, the shape and armature of the P2 dactyli in southern Australian specimens is variable, with the flexor margin unarmed on the distal one-fifth to one-third (fig. 21A–E). Similar variation was seen in the eight New Zealand specimens we examined; in most specimens, the distal one-third of the P2 dactylus was unarmed (fig. 21F) but in one ovigerous female (pcl 12.2 mm; NIWA 54087; Fig. 21G ), the distal one-quarter was unarmed. Similarly, abdominal somite 3 is variously armed with 2–4 spines, albeit usually 4 in adult New Zealand specimens, and almost always 2 in adult southern Australian specimens. Another character used to distinguish M. chydaea was the presence of outer spinules on the third and fourth antennal article, but such spinules were present on all eight of the specimens of M. gracilis we examined from New Zealand. Thus, considered as a whole, Australian material is not reliably morphologically separable from New Zealand specimens, and given the minimal divergence between New Zealand and Western Australian sequences, we consider both populations as probably conspecific.

This brings Munida disgrega Baba, 2005 , to our attention, which was described from 4 small specimens (cl 10.1–13.0 mm) collected from south-eastern Australia and noted as very close to M. chydaea and M. gracilis . In M. disgrega , the flexor margin of the dactylus is unarmed on the distal one-quarter to one-fifth, which is encompassed by the newly observed variation in M. gracilis and M. chydaea . Other distinguishing features of M. disgrega , such as the length of the chela, the lesser striation and broader anterior margin of the thoracic sternum, and proportionately wider eyes apppear to be allometric differences given the small size of the type specimens. Consequently, we cannot reliably distinguish M. disgrega from M. gracilis or M. chydaea

Although we do not have molecular data from eastern Australia (type region of M. chydaea ), on the basis of the low molecular divergence (between New Zealand and south-western Australian specimens) and morphological variability within southern Australian specimens that encompasses those from New Zealand and eastern Australia, we regard M. chydaea and M. disgrega as junior synonyms of M. gracilis . Munida gracilis is closely related to, but clearly distinct from, M. haswelli , with 7.6% divergence in COI and 3.3% in 16S.

Distribution. Southern Australia (Sydney to south-western Australia), 146– 700 m. New Zealand, 365– 610 m.

Figures

Figure 18. Munida gracilis Henderson, 1885. Variation of P2 dactyli. A. female cl 32 mm, 18.3 mm; B. male cl 26.2 mm, pcl 15.5 mm (NMV J55048); C, ovigerous female, cl 32.3 mm, pcl 18.5 mm (SAM C7658); D, male cl 21.2 mm, pcl 11.9 mm (NMV J53574); E, female, cl 30.0 mm (J53574); F, female cl 23.5 mm, pcl 15.8 mm (NIWA 53772); G, ovigerous female, cl 21.0 mm, pcl 12.2 mm (NIWA 54087).

Figure 21. Munida pilorhyncha Miyake and Baba, 1966, female, cl 21.5 mm pcl 16.8 mm, (NMV J551451).