Cymonomus soela Ahyong & Brown 2003
Creators: name: Ahyong, Shane T.
Publisher: name: Zenodo
Year: 2019
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Cymonomidae
Cymonomus
Cymonomus soela

description: Cymonomus soela Ahyong & Brown, 2003
Figs 24, 25, 30E, Tab. 1
Cymonomus soela Ahyong & Brown, 2003: 1368–1371, 1373, figs 3–4.— Poore, 2004: 318, fig. 93a.— Ng et al., 2008: 32.
Holotype: AM P62846, ovigerous female (cl 7.2, pcl 6.4 mm, cw 7.0 mm), off St. Patricks Head, Tasmania, Australia, 41°37.3–39.80' S 148°41.4 –40.50'E, 940–990 m, S05/87/06, RV Soela, coll. K. Graham, 11 July 1987. Paratype: AM P62847, female (cl 7.1 mm, pcl 6.1 mm, cw 6.7 mm), type locality.
Other material examined (all Australia). Queensland: NMV J73046, 1 male (cl 5.4 mm, pcl 4.7 mm, cw 5.2 mm), 2 spent females (cl 6.8 mm, pcl 5.9 mm, cw 6.8 mm; cl 7.4 mm, pcl 6.4 mm, cw 7.6 mm), E of Gladstone, 23°35.22–37.02' S 154°11.64 –11.68'E, 1013–1093 m, IN2017_ V03 _121_138, RV Investigator, 13 June 2017; NMV J73026, 1 male (cl 5.3 mm, pcl 5.5 mm, cw 5.8 mm), 1 ovigerous female (cl 7.2 mm, pcl 6.4 mm, cw 7.1 mm), off Moreton Bay, 26° 57.678 –59.478 ' S 153° 50.850 –50.808 'E, 1071–1138 m, IN2017 _ V03 _104_139, RV Investigator, 10 June 2017; NMV J72956, 1 male (cl 5.3 mm, pcl 4.2 mm, cw 4.3 mm), 1 ovigerous female (cl 7.5 mm, pcl 6.3 mm, cw 7.4 mm), E of Burleigh Heads, 28°03.27–05.82' S 154°04.98 –04.86'E, 999–1013 m, IN2017 _ V03 _100_149, RV Investigator, 9 June 2017; AM P102238, 1 male (cl 5.1 mm, pcl 4.2 mm, cw 4.3 mm, 1 ovigerous female (cl 7.1 mm, pcl 6.1 mm, cw 7.2 mm), 1 spent female (cl 7.6 mm, pcl 6.6 mm, cw 7.5 mm), 1 prespawning female (pcl 5.9 mm, pcl 4.9 mm, cw 5.5 mm), E of Burleigh Heads, 28°03.26–05.82' S 154°04.98 –04.86'E, 999–1013 m, IN2017 _ V03 _100_149, RV Investigator, 9 June 2017.
New South Wales: AM P101655, 1 male (cl 6.7 mm, pcl 5.7 mm, cw 5.9 mm), E of Newcastle, 33°02'24"S 152°37'18"E, 925– 910 m, NZOI stn U219, RV Tangaroa, coll. W. Ponder & R. Springthorpe, 9 October 1982; NMV J72987, 2 males (cl 5.3 mm, pcl 4.5 mm, cw 4.7 mm; cl 5.9 mm, pcl 4.9 mm, cw 5.1 mm), 1 prespawning female (cl 5.6 mm, pcl 4.8 mm, cw 5.4 mm), E of Seal Rocks, 32°28.74–30.42' S 152°59.64 –59.46'E, 1006–1036 m, IN2017 _ V03 _069_117, RV Investigator, 3 June 2017.
Tasmania: SAM C7045, 2 females (cl 8.4 mm, pcl 7.3 mm, cw 8.3 mm; pcl 6.8 mm, cw 7.6 mm), c. 46 nautical miles NE of Babel Island, 39°16.4–16.0' S 148°49.8 –49.6'E, 885–935 m, demersal trawl, F.S. No. 50309, FRV Soela, 27 April 1989.
South Australia: SAM C12939, 1 female (cl 5.7 mm, pcl 5.1 mm, cw 5.4 mm), Great Australian Bight, 34°42.33'S 132°31.86'E, 980–995 m, beam trawl, IN2015-CO1-114- 113, RV Investigator, 24 November 2015; AM P102902, 1 male (cl 6.8 mm, pcl 5.7 mm, cw 6.0 mm), Great Australian Bight, 33° 30.966 –32.256 ' S 130° 15.900 –15.540 'E, 978–1013 m, IN2015-CO2-382-108, RV Investigator; AM P102903, 1 ovigerous female (cl 8.6 mm, pcl 7.2 mm, cw 8.4 mm), 1 prespawning female (cl 5.8 mm, pcl 4.9 mm, cw 5.4 mm), Great Australian Bight, 33° 30.966 –32.256 ' S 130° 15.900 –15.540 'E, 978–1013 m, IN2015-CO2-382- 107, RV Investigator, 15 December 2015; AM P102901, 1 male (cl 7.1 mm, pcl 6.0 mm, cw 6.4 mm), Great Australian Bight, 35° 09.162 –10.932 ' S 134°06.54 –06.54'E, 965–1077 m, IN2015-CO2-131-127, RV Investigator, 15 December 2015. Description. Carapace quadrate, almost square, lateral margins subparallel; regions indistinct; cervical groove indistinct, slightly more pronounced in males than females; lower pterygostomian region swollen; anterior and anterolateral surfaces with few setae, almost glabrous. Anterolateral spine short, blunt, conical, inclined laterally. Dorsal and lateral surfaces entirely covered with rounded granules, with granules becoming slightly larger and more elongate anterolaterally, bluntly conical, not globose. Fronto-orbital margin (excluding rostrum and outer-orbital processes) slightly advanced beyond anterolateral margins, more pronounced in males than females; about 0.6 anterior carapace width; outer orbital processes stout, elongate, directed anteriorly, situated below plane of rostrum, laterally bluntly spinulate, apex acute, half as long to as long as rostrum. Rostrum almost half to half-length of eyestalks; 0.13–0.21 pcl; slender, tapering to acute apex, minutely granulate dorsally and laterally.
Eyestalks divergent (25–30° from median axis), margins subparallel for most of length, slender, flattened, granulate, fused to carapace below rostral base but demarcation distinct, reaching anteriorly almost to end of antennular peduncle article 1; cornea apparently vestigial, not pigmented.
Epistome with small cluster of granules at base of rostrum and blunt tubercle mesial to base of antennules, otherwise smooth; small spine mesial to base of antenna.
Antennular peduncle 1.00–1.10 pcl (male), 0.78–0.90 (female); articles 1 and 2 minutely granulate; article 3 smooth. Antennal articles minutely spinulate or granulate.
Maxilliped 3 ischiobasis subquadrate, granulate; longitudinal sublateral groove; ischium and basis demarcated by faint groove. Merus as long as ischium, length twice width, tapering distally to rounded apex; surface and margins with short, blunt spines. Dactylus unarmed; propodus and carpus spinulate, granulate. Exopod granulate, reaching end of, or slightly overreaching merus of endopod.
Chelipeds (pereopod 1) equal in size and ornamentation, sparsely setose. Merus granulate. Carpus granulate, dorsal margin with prominent conical and allantoid spines flanked by shorter blunt spines. Propodus palm surfaces entirely granulate, dorsal and ventral margins with granules and elongate tubercles, extending onto proximal half of pollex. Dactylus longer than dorsal palm length; dorsal margin with short, blunt, slender spines and granules; with longitudinal carina on outer surface, occlusal surfaces of dactylus and pollex crenulated, with slight gape when fingers closed.
Pereopods 2 and 3 very sparsely setose, almost glabrous; all articles except for dactylus granulate; propodus, carpus and merus with coarsely granulate extensor margins; dactylus broadly curved, smooth, with longitudinal rib. Pereopod 3 longest, merus 1.29–1.47 pcl (male), 1.02–1.26 (female); dactylus about as long as combined length of propodus and carpus.
Pereopods 4 and 5 granulate, unarmed, almost glabrous; shorter than pereopod 3 merus in males, about as long as merus in females; propodus distoextensor margin unarmed; dactylus markedly shorter than propodus, falcate, with corneous apex and 4 or 5 obliquely inclined, corneous spines on flexor margin. Pereopod 5 merus, when folded against carapace, reaching midlength of carapace.
Thoracic sternite 3 pentagonal, 1.7 × wider than long; proximal lateral margins divergent posteriorly; surface granulate. Margins of sternites 4 and 5 granulate.
Abdomen surface finely granulate or minutely spinulate. Pleotelson without trace of demarcation between somite 6 and telson; apex obtuse, blunt; in males, subtriangular, twice 2.0–2.1 × length; in females, pentagonal, width 2.1–2.4 × length.
Gonopod 1 distal article cannulate, forming copulatory tube, with moderately long distal setae. Gonopod 2 with articles fused; distomesial margin slightly hollowed, apex acute.
Egg diameter 1.19–1.31.
Remarks. Cymonomus soela closely resembles C. tesseris sp. nov. and C. dianae sp. nov. (both from Western Australia) and C. clarki (eastern New Zealand) in sharing the carapace frontal margin that is only weakly advanced beyond the anterolateral margins in females, eyestalks that are distinctly longer than the rostrum, and well developed outer orbital processes. Cymonomus soela differs from C. tesseris by the proportional length of the walking legs and antennules (see account of C. tesseris). Cymonomus soela is readily distinguished from C. dianae and C. clarki by its smaller anterolateral carapace spines, comparatively thicker eyestalks, almost glabrous rather than distinctly setose anterolateral carapace margins, and the coarser dorsal carapace granulation (Figs 16A, 24A). Cymonomus soela further differs from C. clarki in the shorter pereopod 5 (Fig. 24A) (merus reaching almost to the midlength rather than anterior one-third of the carapace; Fig. 10A) and from C. dianae in the distinctly granulate (Fig. 24A) (rather than smooth or microscopically granulate; Fig. 16A) cheliped palms.
Cymonomus soela was previously known only from Tasmania, but is herein reported from off southeastern Queensland, New South Wales and South Australia (Great Australian Bight). Males of C. soela are reported here for the first time. Typical of cymonomids, sexual dimorphism in C. soela is evident in the proportionally longer antennular peduncle and walking legs of males. As in C. dianae and C. deforgesi, mature female C. soela have a slightly more inflated carapace than in males rendering the cervical groove less prominent. Similarly, the fronto-orbital margin in males protrudes slightly further forwards (relative to the anterolateral margins) than in females (Fig. 24A, J, 30E).
The relatively small series of C. soela examined here exhibits apparently near continuous clinal geographic variation in walking leg length (Table 1). As measured by the proportional length of the pereopod 3 merus, the walking legs of females are longest in eastern Australian specimens (1.19–1.26 pcl), of intermediate length in Tasmanian specimens (1.10–1.16 pcl), and shortest in South Australian specimens (1.00–1.08 pcl). A similar trend is evident in males, although male C. soela are yet to be collected from Tasmania. Such clinal trends are not known from other species of Cymonomus. Moreover, the morphometric range in the pereopod 3 merus length in the present series (male 1.19–1.47 pcl, female 1.00–1.26 pcl) exceeds typical intraspecific variation of about 10% observed in other species reported here and elsewhere (e.g., Ahyong & Ng, 2017). In the absence of clear morphological discontinuities and the lack of males from Tasmania (the intermediate locality), all are treated as conspecific pending further study.
Distribution. Eastern Australia from off southeastern Queensland, New South Wales, Tasmania and South Australia (Great Australian Bight) (Fig. 25); 885–1193 m.
description: Published as part of Ahyong, Shane T., 2019, The Cymonomid Crabs of New Zealand and Australia (Crustacea: Brachyura: Cyclodorripoida), pp. 33-69 in Records of the Australian Museum 71 (2) on pages 59-62, DOI: 10.3853/j.2201-4349.71.2019.1682, http://zenodo.org/record/3838013