Statommatia apta ( 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

publication ID

http://doi.org/10.11646/zootaxa.4209.1.1

publication LSID

lsid:zoobank.org:pub:849BAB5C-464A-4B4A-A586-5742411EDC01

DOI

http://doi.org/10.5281/zenodo.5617173

persistent identifier

http://treatment.plazi.org/id/F16BFB33-FFEB-FFB1-FF6A-F97AFAFAF8BD

treatment provided by

Plazi

scientific name

Statommatia apta ( Rathbun, 1914 )
status

n. comb.

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

( Figs. 16 View FIGURE 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 View Materials ), Philippines, between Cebu and Bohol, Lauis Point Light, Albatross , stn 5419, 09°58’30”N, 123°46’E, 320 m, 25.03.1909. GoogleMaps  

Other material examined. Philippines. PANGLAO 2005: 2 males (8.4 × 10.1 mm, 8.5 × 10.3 mm) ( ZRC 2015.237 View Materials ), Bohol Sea, stn CP2390, 09°27’N, 123°43'E, 627–645 m, 30.05.2005 GoogleMaps   ; 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 View Materials ), stn CP2656, 16°02’N, 121°53’E, 262‒278 m, 20.05.2007 GoogleMaps   .

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 GoogleMaps   ; 1 female (MNHN-IU-2011-1842), off Sepik River, stn CP3701, 03°57’S, 144°41’E, 198–219 m, 01.10.2010 GoogleMaps   ; 9 males, 2 females (MNHN-IU-2014-17790), 4 males, 2 females ( ZRC 2015.240 View Materials , 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 GoogleMaps   ; 2 males (MNHN-IU- 2011-2044), Astrolabe Bay , stn CP3711, 05°23’S, 145°48’E, 434– 447 m, 05.10.2010 GoogleMaps   .— 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 GoogleMaps   ; 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 GoogleMaps   ; 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 GoogleMaps   ; 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 View FIGURE 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 View FIGURE 26 A, B) with semicircular median lobe with deep median fissure, semicircular lateral margins. Eye peduncle ( Fig. 26 View FIGURE 26 A, B) filling orbit, short, immobile; cornea reduced, pigmented. Third maxillipeds ( Fig. 33 View FIGURE 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 View FIGURE 16 A‒C; 45C, D; 46) subequal in length, slightly dissimilar in female, heteromorphic in males; fingers of minor   chela ( Figs. 45 View FIGURE 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 View FIGURE 45 C; 46A‒C); cutting margin of pollex with proximal 2/3 flattened, shelf-like ( Fig. 46 View FIGURE 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 View FIGURE 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 View FIGURE 42 M), hollow region in median part. Inner margin of cheliped carpus with short distal tooth ( Fig. 16 View FIGURE 16 A, B). Inner margin of basis-ischium of adult major cheliped gently granuliform ( Fig. 16 View FIGURE 16 A). Ambulatory legs ( Fig. 16 View FIGURE 16 A‒C) unarmed, proportionally short. P5 dactylus gently upcurved ( Fig. 16 View FIGURE 16 A); P5 merus 0.6 cl. Fused thoracic sternites 1, 2 ( Fig. 54 View FIGURE 54 A, B) semicircular, broad, short; fused thoracic sternites 3, 4 ( Figs. 54 View FIGURE 54 A, B; 88A; 91E) broad. Male pleon ( Figs. 54 View FIGURE 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 View FIGURE 61 A). G1 (77A‒C) with stout basal part; distal part slender, straight, tapering, with short spinules. G2 ( Fig. 77 View FIGURE 77 D) about half G1 length, straight, slender, thin, distal segment short, straight. Somites of female pleon ( Fig. 88 View FIGURE 88 A) with convex lateral margins; telson proportionally long. Sterno-pleonal cavity of female ( Fig. 91 View FIGURE 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 View FIGURE 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 View FIGURE 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 View FIGURE 45 G) and Angustopelta cribrorum   ( Fig. 41 View FIGURE 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.

USNM

Smithsonian Institution, National Museum of Natural History

ZRC

Zoological Reference Collection, National University of Singapore

Kingdom

Animalia

Phylum

Arthropoda

Class

Malacostraca

Order

Decapoda

Family

Chasmocarcinidae

Genus

Statommatia

Loc

Statommatia apta ( Rathbun, 1914 )

Ng, Peter K. L. & Castro, Peter 2016
2016
Loc

Hephthopelta apta

Zarenkov 1972: 238
Serene 1964: 240
Estampador 1959: 90
Tesch 1918: 233
Rathbun 1914: 148
1914