Statommatia apta ( Rathbun, 1914 ) Rathbun, 1914

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182 : 73-75

Statommatia apta ( Rathbun, 1914) , n. comb.

( Figs. 16 A‒C; 26A, B; 33A, B; 42M; 45C, D; 46; 54A, B; 61A; 77A‒D; 88A; 91E)

Hephthopelta apta Rathbun, 1914: 148 [type locality: Philippines].— Tesch 1918: 233 [in key].— Estampador 1959: 90 [in list].— Serène 1964a: 240 [in list], 241, 242 [in key]; 1968: 92 [in list].— Zarenkov 1972: 238, fig. 4-3 [ Vietnam].—Ng et al. 2008: 76 [in list].—Ng & Rahayu 2014: fig. 2C, D [ Philippines].

Type material. Holotype male (7.8 × 9.4 mm) ( USNM 46389 ), Philippines, between Cebu and Bohol, Lauis Point Light, Albatross , stn 5419, 09°58’30”N, 123°46’E, 320 m, 25.03.1909.

Other material examined. Philippines. PANGLAO 2005: 2 males (8.4 × 10.1 mm, 8.5 × 10.3 mm) ( ZRC 2015.237 ), Bohol Sea, stn CP2390, 09°27’N, 123°43'E, 627–645 m, 30.05.2005 ; 1 female (ZRC 2015.238), stn CP2397, 09°36.6’N, 123°42.9’E, 607‒642 m, 31.05.2005; 1 male (10.1 × 12.3 mm, carapace damaged) (ZRC 2013.1727), stn CP2398, 09°34.2’N, 123°41.8’E, 658‒713 m, 31.05.2005.— AURORA 2007: 2 males (5.6 × 6.4 mm, 5.9 × 7.1 mm) ( ZRC 2015.239 ), stn CP2656, 16°02’N, 121°53’E, 262‒278 m, 20.05.2007 .

Papua New Guinea. BIOPAPUA: 1 female (MNHN-IU-2011-1166), Open Bay , stn CP3666, 04°40’S, 151°33’E, 760–866 m, 23.09.2010 ; 1 female (MNHN-IU-2011-1842), off Sepik River, stn CP3701, 03°57’S, 144°41’E, 198–219 m, 01.10.2010 ; 9 males, 2 females (MNHN-IU-2014-17790), 4 males, 2 females ( ZRC 2015.240 , ex MNHN-IU-2014-17790), 1 female (MNHN-IU- 2011-2241), 2 males, 1 ovigerous female (6.1 × 7.3 mm) (MNHN-IU-2011-5200), 3 males (MNHN-IU- 2011-2030), Astrolabe Bay , stn CP3710, 05°22’S, 145°48’E, 372–384 m, 05.10.2010 ; 2 males (MNHN-IU- 2011-2044), Astrolabe Bay , stn CP3711, 05°23’S, 145°48’E, 434– 447 m, 05.10.2010 .— PAPUA NUGUINI: 1 male (MNHN-IU-2013-9020), 2 males, 2 females (MNHN-IU-2013- 11599), W. Kranket I., stn CP3948, 05°12’S, 145°51'E, 363–388 m, 26.11.2012 ; 1 male, 1 female (MNHN-IU- 2013-9010), 2 males (MNHN-IU-2013-9011), 2 males, 3 females, 1 ovigerous female (MNHN-IU-2013-9017), W. Kranket I., stn CP3949, 05°12’S, 145°51'E, 380–407 m, 26.11.2012; 10 males, 16 females (MNHN-IU-2013- 9023), Astrolabe Bay , stn CP4023, 05°22’S, 145°48'E, 340–385 m, 14.12.2012 ; 2 males (MNHN-IU-2013-9013), stn CP4024; 1 male, 1 female (MNHN-IU-2013-11664), Astrolabe Bay , stn CP4025, 05°21’S, 145°49'E, 520–525 m, 14.12.2012 ; 1 female (MNHN-IU-2013-7978), W. Kariru I., Bismarck Sea, stn CP4048, 03°20’S, 143°28'E, 325–345 m, 19.12.2012.

Diagnosis. Carapace ( Fig. 16 A‒C) subtrapezoidal, convex dorsally, 1.2 wider than long; front bilobed, with shallow median cleft; anterolateral margins arcuate, minutely granular, without distinct lobes or teeth. Posterior margin of epistome ( Fig. 26 A, B) with semicircular median lobe with deep median fissure, semicircular lateral margins. Eye peduncle ( Fig. 26 A, B) filling orbit, short, immobile; cornea reduced, pigmented. Third maxillipeds ( Fig. 33 A, B) not filling buccal cavern when closed; merus ovate, outer margin curved, anteroexternal angle rounded; ischium quadrate, about same length as merus. Chelipeds ( Figs. 16 A‒C; 45C, D; 46) subequal in length, slightly dissimilar in female, heteromorphic in males; fingers of minor chela ( Figs. 45 D; 46D‒G) subcircular in cross-section, not distinctly laterally flattened, gently tapering to tip, scissor-like, scissor-like, cutting margins with distinct teeth; cutting margin of major chela of males with short, blunt teeth, dactylus arched ( Figs. 45 C; 46A‒C); cutting margin of pollex with proximal 2/3 flattened, shelf-like ( Fig. 46 A‒C); lower, proximal portion of propodus of small male cheliped flattened, bordered by thick tubercles forming flat ridge on inner, outer margins ( Fig. 46 D‒K), smooth margin in females. Ventral surface of cheliped merus with row of small tubercles (sharp in some individuals) along outer margin, inner margin unarmed ( Fig. 42 M), hollow region in median part. Inner margin of cheliped carpus with short distal tooth ( Fig. 16 A, B). Inner margin of basis-ischium of adult major cheliped gently granuliform ( Fig. 16 A). Ambulatory legs ( Fig. 16 A‒C) unarmed, proportionally short. P5 dactylus gently upcurved ( Fig. 16 A); P5 merus 0.6 cl. Fused thoracic sternites 1, 2 ( Fig. 54 A, B) semicircular, broad, short; fused thoracic sternites 3, 4 ( Figs. 54 A, B; 88A; 91E) broad. Male pleon ( Figs. 54 A, B; 61A) lateral margins of somite 6, fused somites 3‒5 slightly convex; postero-lateral regions as in rest of somite, not swollen; telson proportionally long. Sterno-pleonal cavity deep, press-button for pleonal holding as small, short tubercle posterior to thoracic sternal suture 4/5 near edge of sterno-pleonal cavity. Male thoracic sternite 8 long, rectangular; “supplementary plate” long, subrectangular; structures tightly appressed with most of penis concealed (e.g., Fig. 61 A). G1 (77A‒C) with stout basal part; distal part slender, straight, tapering, with short spinules. G2 ( Fig. 77 D) about half G1 length, straight, slender, thin, distal segment short, straight. Somites of female pleon ( Fig. 88 A) with convex lateral margins; telson proportionally long. Sterno-pleonal cavity of female ( Fig. 91 E) deep, vulvae relatively close together, located on outer margins of cavity close to suture 5/6.

Remarks. The propodus of the minor cheliped of males of S. apta is flat and surrounded by elevated ridges or crests formed by thick tubercles along the inner and outer margins. The cavity thus formed when the propodus is flexed against the similarly hollow merus was hypothesized by Rathbun (1914: 149, as Hephthopelta apta ) as “a passage of water into the left branchial canal.” The large, round gap formed by the closed and strongly curved fingers of the major cheliped ( Fig. 46 A‒C) was suggested as resulting, when flexed, into “an oval area fringed with hair” resting on the opening of the opposite branchial chamber. This characteristic shape is absent in females of S. apta ( Fig. 16 C). Gaping fingers of the major male cheliped, however, can also be observed in other chasmocarcinines such as Statommatia malagasy n. sp. ( Fig. 45 G) and Angustopelta cribrorum ( Fig. 41 C).

There is a visible variation in the length of the ambulatory legs, with females and small males on hand having legs that are shorter than in the largest males.

Distribution. Western Pacific Ocean ( Philippines, Vietnam, Papua New Guinea). Depth: 198‒ 866 m.

Figures

FIGURE 16. Overall dorsal view, chela, ambulatory legs and pleon of species of Statommatia n. gen. A, S. apta, Philippines: holotype male 7.8 × 9.4 mm (USNM 46839); B, S. apta, Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); C, S. apta, Philippines: female 8.5 × 10.6 mm (ZRC 2015.238); D, S. knudseni, New Caledonia: holotype male 4.7 × 6.9 mm (ZMUC CRU- 6974); E, S. malagasy n. sp., Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU- 2010 - 4370 a); F, S. malagasy n. sp., Madagascar: paratype female 9.4 × 8.1 mm (ZRC 2015.215); G, S. pubescens, South China Sea: holotype male 5.0 × 7.9 mm (after Chen 1998: fig. 23 - 1 ‒ 4, 6); H, S. granulosa n. sp., New Caledonia: holotype male 4.1 × 4.7 mm (MNHN-IU- 2013 - 9454).

FIGURE 26. Frontal view of species of Statommatia n. gen. and Tenagopelta n. gen. A, Statommatia apta, Philippines: holotype 7.8 × 9.4 mm (USNM 46389); B, Statommatia apta, Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); C, Statommatia malagasy n. sp., Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU- 2010 - 4370 a); D, Statommatia knudseni, New Caledonia: holotype male 4.7 × 6.9 mm (ZMUC CRU- 6974); E, Statommatia granulosa n. sp., New Caledonia: holotype male 4.1 × 4.7 mm (MNHN-IU- 2013 - 9454); F, Tenagopelta pacifica n. sp., Philippines: holotype male 10.3 × 11.9 mm (NMCR); G, Tenagopelta brachyphallus n. sp., Australia: holotype male 6.1 × 6.9 mm (NMV J 61680); H, Tenagopelta potens, Papua New Guinea: male 11.8 × 13.8 mm (MNHN-IU- 2011 - 1504).

FIGURE 33. Third maxilliped of species of Statommatia n. gen. and Tenagopelta n. gen. A, Statommatia apta, Philippines: holotype male 7.8 × 9.4 mm (USNM 46389); B, Statommatia apta, Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); C, Statommatia knudseni, New Caledonia: holotype male 4.7 × 6.9 mm (ZMUC CRU- 6974); D, Statommatia pubescens, South China Sea: holotype male 5.0 × 7.9 mm (after Chen 1998: fig. 23 - 5); E, Statommatia malagasy n. sp., Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU- 2010 - 4370 a); F, Statommatia granulosa n. sp., New Caledonia: holotype male 4.1 × 4.7 mm (MNHN-IU- 2013 - 9454); G, Tenagopelta pacifica n. sp., Philippines: holotype male 10.3 × 11.9 mm (NMCR); H, Tenagopelta brachyphallus n. sp., Australia: holotype male 6.1 × 6.9 mm (NMV J 61680); I, Tenagopelta potens, Papua New Guinea: male 11.8 × 13.8 mm (MNHN-IU- 2011 - 1504).

FIGURE 41. Chelae of species of Angustopelta n. gen. A, B, A. aurita, Philippines: male 9.2 × 10.6 mm (ZRC 2015.250); C, D, A. cribrorum, Japan: holotype male 13.6 × 14.9 mm (USNM 46388); E, F, A. cribrorum, Taiwan: male 9.9 × 11.6 mm (ZRC 2015.214); G, H, A. robusta n. sp., Vanuatu: holotype male 9.3 × 10.7 mm (MNHN-IU- 2010 - 5616); I, J, A. modesta n. sp., Solomon Islands: holotype male 13.3 × 15.1 mm (MNHU-IU- 2013 - 9038).

FIGURE 42. P 4, P 5, and merus of cheliped of species of Angustopelta n. gen. A, A. robusta n. sp., Vanuatu: paratype male 12.3 × 13.3 mm (ZRC 2015.255); B, A. robusta n. sp., Vanuatu: paratype female 13.4 × 15.1 mm (MNHN-IU- 2010 - 5616); C, A. robusta n. sp., Vanuatu: paratype male 12.5 × 14.8 mm (MNHN-IU- 2013 - 9041); D, A. modesta n. sp., Solomon Islands: holotype male 13.3 × 15.1 mm (MNHU-IU- 2013 - 9038); E, A. modesta n. sp., Solomon Islands: paratype female 13.1 × 15.3 mm (ZRC 2015.258); F, A. aff. modesta n. sp., Papua New Guinea: female 9.3 × 9.9 mm (MNHN-IU- 2011 - 3307); G, Hephthopelta lugubris, Papua New Guinea: female 9.8 × 10.9 mm (MNHN-IU- 2011 - 2657), major cheliped; H, Angustopelta aurita, Philippines: female 10.9 × 12.7 mm (ZRC 2015.248), minor cheliped; I, Tenagopelta pacifica n. sp., Indonesia: male 11.0 × 12.4 mm (MNHU-IU- 2013 - 9053), minor cheliped; J, Chinommatia cavimanus, Philippines: male 9.7 × 11.5 mm (ZRC 2015.234), minor cheliped; K, Chinommatia cavimanus, Philippines: male 7.6 × 9.3 mm (ZRC 2015.231), minor cheliped; L, Notopelta mortenseni, Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU- 7397), major cheliped; M, Statommatia apta, Philippines: males 8.5 × 10.3 mm (ZRC 2015.237), minor cheliped; N, Statommatia malagasy n. sp., Madagascar: male 8.8 × 11.0 mm (MNHN-IU- 2010 - 4370 b), minor cheliped.

FIGURE 45. Chelae of species of Statommatia n. gen. and Notopelta n. gen. A, B, Notopelta mortenseni, Indonesia: holotype male 5.0 × 6.9 mm (ZMUC CRU- 7397); C, D, Statommatia apta, Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); E, F, S. knudseni, New Caledonia: holotype male 4.7 × 6.9 mm (ZMUC CRU- 6974); G, H, Statommatia malagasy n. sp., Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU- 2010 - 4370 a); I, J, Statommatia granulosa n. sp., New Caledonia: holotype male 4.1 × 4.7 mm (MNHN-IU- 2013 - 9454).

FIGURE 46. Chelae of Statommatia apta, male 10.1 × 12.3 mm (ZRC 2013.1727). A – C, outer view of right major chela (different angles); D, E, outer view of left minor chela; F, G, subventral view of left minor chela; H, I, ventral view of left minor chela; J, K, inner view of left minor chela.

FIGURE 54. Anterior thoracic sternum and male pleon of species of Statommatia n. gen. and Tenagopelta n. gen. A, Statommatia apta, Philippines: holotype 7.8 × 9.4 mm (USNM 46389); B, Statommatia apta, Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); C, Statommatia malagasy n. sp., Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU- 2010 - 4370 a); D, E, Statommatia knudseni, New Caledonia: holotype male 4.7 × 6.9 mm (ZMUC CRU- 6974); F, Tenagopelta pacifica n. sp., Philippines: holotype male 10.3 × 11.9 mm (NMCR); G, Tenagopelta brachyphallus n. sp., Australia: holotype male 6.1 × 6.9 mm (NMV J 61680); H, Tenagopelta potens, Papua New Guinea: male 11.8 × 13.8 mm (MNHN-IU- 2011 - 1504).

FIGURE 61. Thoracic sternites 7 and 8 and male pleon of species of Statommatia n. gen. and Tenagopelta n. gen. A, Statommatia apta, Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); B, Statommatia knudseni, New Caledonia: holotype 4.7 × 6.9 mm (ZMUC CRU- 6974); C, Statommatia malagasy n. sp., Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU- 2010 - 4370 a); D, Statommatia granulosa n. sp., New Caledonia: holotype male 4.1 × 4.7 mm (MNHN-IU- 2013 - 9454); E, Tenagopelta pacifica n. sp., Philippines: holotype male 10.3 × 11.9 mm (NMCR); F, Tenagopelta brachyphallus n. sp., Australia: holotype male 6.1 × 6.9 mm (NMV J 61680); G, Tenagopelta potens, Papua New Guinea: male 11.8 × 13.8 mm (MNHN-IU- 2011 - 1504).

FIGURE 77. Gonopods of species of Statommatia n. gen. A ‒ D, S. apta, Philippines: male 5.9 × 7.1 mm (ZRC 2015.239); E ‒ H, S. knudseni, New Caledonia: holotype male 4.7 × 6.9 mm (ZMUC CRU- 6974); I ‒ L, S. malagasy n. sp., Madagascar: holotype male 9.9 × 12.4 mm (MNHN-IU- 2010 - 4370 a). A ‒ C, ventral view of right G 1 [left one damaged]; E, I, ventral view of left G 1; B, dorsal view of distal part of right G 1; C, ventral view of distal part of right G 1; F, J, ventral view of distal part of left G 1; G, K, dorsal view of distal part of left G 1; D, H, L, left G 2. Scales: A, D, E, H, I, L = 0.5 mm; B, C, F, G, J, K = 0.1 mm.

FIGURE 88. Female thoracic sternum and pleon of species of Statommatia n. gen., Tenagopelta n. gen., Microtopsis and Megaesthesius. A, Statommatia apta, Philippines: female 8.5 × 10.6 mm (ZRC 2015.238); B, Statommatia malagasy n. sp., Madagascar: paratype female 9.4 × 8.1 mm (ZRC 2015.215); C, Tenagopelta pacifica n. sp., Philippines: female 9.2 × 10.4 mm (ZRC 2015.187); D, Tenagopelta brachyphallus n. sp., Australia: female 6.9 × 7.6 mm (NMV J 61680); E, Microtopsis takedai, Japan: paratype female 3.6 × 2.7 mm (ZRC 2012.0146); F, Megaesthesius sagedae, Singapore: female 3.0 × 3.6 mm (ZRC 2013.1804); G, Megaesthesius migmus, Philippines: paratype female 3.9 × 4.5 mm (ZRC 2015.245); H, Alainthesius bertrandi n. sp., Papua New Guinea: female 5.6 × 6.9 mm (MNHN-IU- 2013 - 9012). Vulvae exposed in E.

FIGURE 91. Vulvae of species of Hephthopelta, Angustopelta n. gen., Chinommatia n. gen., Statommatia n. gen. and Tenagopelta n. gen. A, Hephthopelta lugubris, Australia: ovigerous female 6.3 × 6.6 mm (NMV J 61083); B, Angustopelta aurita, Philippines: female 8.7 × 10.0 mm (ZRC 2015.253); C, Angustopelta robusta n. sp., Vanuatu: paratype female 13.4 × 15.1 mm (MNHN-IU- 2010 - 5616); D, Chinommatia cavimanus, Philippines: female 7.6 × 9.0 mm (ZRC 2015.228); E, Statommatia apta, Philippines: female 8.5 × 10.6 mm (ZRC 2015.238); F, Statommatia malagasy n. sp., Madagascar: paratype female 9.4 × 8.1 mm (ZRC 2015.215); G, Tenagopelta pacifica n. sp., Philippines: female 9.2 × 10.4 mm (ZRC 2015.187); H, Tenagopelta brachyphallus n. sp., Australia: female 6.9 × 7.6 mm (NMV J 61680).