Homologenus malayensis Ihle, 1912

Ng, Peter K. L. & Forges, Bertrand Richer de, 2017, On a collection of Homolidae from the South China Sea, with descriptions of two new species of Homologenus A. Milne-Edwards, in Henderson, 1888, and the identities of Homologenus malayensis Ihle, 1912, and Lamoha superciliosa (Wood-Mason, in Wood-Mason & Alcock, 1891), Raffles Bulletin of Zoology 65, pp. 243-268 : 251-255

Homologenus malayensis Ihle, 1912

( Figs. 8–12 , 18A, B , 20A, B , 21A–C , 24I, J )

Homologenus malayensis Ihle, 1912: 209 . – Ihle, 1913: 70, figs. 25, 31, 36–38, pl. 2, figs. 13–15. – Balss, 1940: fig. 98. – Guinot, 1979: 232. – Guinot & Richer de Forges, 1981: 553. – Guinot & Richer de Forges, 1995: 476, figs. 65 A, B, 66 d. – Ng et al., 2008: 40.

Material examined. 2 males (carapace widths 6.2 mm, 6.1 mm; both with broken rostrums) ( ZRC 2016.0194 , ex MNHN-IU-2011-2712), station CP 3762, 03°57′S 153°49′E, 995–1050 m, Papua New Guinea, coll. BIOPAPUA, 14 October 2010 . – 1 ovigerous female (11.8 × 9.6 mm; rostrum broken) (MNHN-IU-2014-18963), station CP 4449, New Ireland, Papua New Guinea, 02°10′S 150°11′E, 623–908 m, coll. KAVIENG 2014, 1 September 2014 . – 1 ovigerous female (14.6 × 14.0 mm) ( ZRC 2016.0195 , ex MNHN- IU-2014-18991), station CP 4442, New Ireland, Papua New Guinea, 02°164S 150°36′E, 892–925 m, coll. KAVIENG 2014, 31 August 2014 . – 1 ovigerous female (13.8 × 12.3 mm) (MNHN-IU-2014-18813), station CP 4436, New Ireland, Papua New Guinea, 02°16′S 150°45′E, 1128–1135 m, coll. KAVIENG 2014, 30 August 2014 . – 1 female (11.4 × 10.6 mm) (MNHN-IU-2014-18809), station CP 4433, New Ireland, Papua New Guinea, 02°16′S 150°48′E, 1056–1200 m, coll. KAVIENG 2014, 30 August 2014 . – 1 ovigerous female (14.9 × 9.9 mm) (MNHN-IU-2014-8052), station CP 4431, New Ireland, Papua New Guinea, 02°16′S - 150°40′E, 830–894 m, coll. KAVIENG 2014, 29 August 2014 . – 1 male (10.7 × 6.2 mm) (MNHN-IU-2015-1182), station CP 4434, New Ireland, Papua New Guinea, 02°19′S 150°47′E, 1066–1200 m, coll. KAVIENG 2014, 30 August 2014 . – 2 ovigerous females (16.0 × 13.9 mm, 16.1 × 12.9 mm) ( ZRC 2016.0196 , ex MNHN-IU-2015-80), station CP 4245, 04°06′S 148°10′E, northwest of Vitu Islands, Bismarck Sea, 790–808 m, coll. MADEEP 2014, 22 April 2014 .

Colour. The carapace is essentially dirty white to pale pink overall but the numerous setae trap a great deal of sediment, giving the animals an overall light brown appearance in life ( Fig. 24I, J ).

Remarks. In their revision of the genus, Guinot & Richer de Forges (1995) examined and figured the types and clarified the identity of H. malayensis . They characterised it by the presence of a distinct gastric spine, absence of distinct spines behind the lateral spine, the distal margin of P2 to P4 armed only with a single spine and unarmed ventral margin of P4 ( Figs. 8B , 12G, K ) ( Guinot & Richer de Forges, 1995: 469–470). They recorded the species from northwest of Sulawesi in Indonesia (type locality), southern Java and southern Philippines ( Guinot & Richer de Forges, 1995: 476) with a doubtful record from Japan. Guinot & Richer de Forges (1995: 476, fig. 65) selected a lectotype female among the material of Ihle (1912, 1913) and figured the carapace ( Figs. 8A, B, F, G , 9A ). These agree very well with the material from Papua New Guinea ( Figs. 10–12). The figure of the G1 by Ihle (1913: fig. 37) ( Fig. 8D ) was made in situ and shows the laterally flattened distal chitinous part; it actually agrees with other material examined here when viewed under the equivalent orientation ( Fig. 12C ).

Guinot & Richer de Forges (1995: 476) also recorded several specimens from Indonesia and southern Philippines and referred them to H. malayensis on the basis of the ambulatory leg armature. Considering their provenance, it seems reasonable they also belong to this species as presently defined. The doubtful record by Nagai (1994) from Japan is here referred to the present new species, H. exilis .

The figures of H. malayensis by Ihle (1913: pl. 2 figs. 13, 14) ( Fig. 8A, B ) depict a female specimen which apparently has slightly shorter and stouter legs than the material we have on hand from Papua New Guinea ( Fig. 10). However, this is just the consequence of how the legs are oriented when drawn and/or photographed. When viewed obliquely, the legs, especially the merus, appears more slender than it actually is, giving the impression of being more slender. Charles Fransen (The Naturalis, Leiden) kindly photographed the types of H. malayensis for us ( Fig. 9 ) and the proportions of their ambulatory legs agree very well with the material here figured from Papua New Guinea ( Fig. 10).

In the series of specimens examined (as well as what is known about H. malayensis , cf. Guinot & Richer de Forges, 1995), there is usually only one spine on the anterolateral angle of the merus of the third maxilliped ( Fig. 8G ). Two ovigerous female specimens from Papua New Guinea (13.8 ×

12.3 mm, MNHN-IU-2014-18813; 16.0 × 13.9 mm, MNHN- IU-2015-80), however, have two spines ( Fig. 11C ), so this character is not always reliable.

Figures

Fig. 8. Homologenus malayensis Ihle, 1912. A, B, F, G, lectotype female (15.5 × 9.8 mm, ZMA DE 102.967), station 122, northern Sulawesi, 1°58.5′N 125°00.5′E, Indonesia, 1264–1165 m, coll. SIBOGA Expedition, Weber, 17 July 1899 (A, B, after Ihle, 1913: pl. 2 figs. 13, 14; F, G, after Guinot & Richer de Forges, 1995: fig. 65); C, type specimen, sex not stated (after Ihle, 1913: fig. 31); D, E, paralectotype male (size not specified) (after Ihle, 1913: figs. 37, 38). A, overall habitus; B, ventral view of cephalothorax; C, left P5 pseudochela (propodus and dactylus); D, left G1; E, left G2; F, dorsal view of carapace; G, ventral view of cephalothorax.

Fig. 9. Homologenus malayensis Ihle, 1912, overall habitus. A, lectotype female (15.5 × 9.8 mm) (NNM ZMA DE 102.967), station 122, northern Sulawesi, 1°58.5′N 125°00.5′E, Indonesia, 1264–1165 m, coll. SIBOGA Expedition, Weber, 17 July 1899; B, paralectotype (11.3 × 6.1 mm) (NNM ZMA DE 102.967), same data as lectotype. Photographs courtesy of Charles Fransen.

Fig. 18. Carapace of Homologenus species. A, H. malayensis Ihle, 1912, male (carapace width 6.2 mm, rostrum damaged) (ZRC 2016.0194), Papua New Guinea; B, H. malayensis Ihle, 1912, female (16.0 × 13.9 mm) (ZRC 2016.0194), Papua New Guinea; C, H. donghaiensis Chen, 1986, holotype male (11.0 × 10.3 mm) (IOCAS KY8B-71), East China Sea (photograph: W. Jiang); D, H. exilis n. sp., paratype male (10.2 × 7.4 mm) (ZRC 2016.0568), South China Sea; E, H. exilis n. sp., holotype ovigerous female (13.5 × 10.4 mm) (NTOU), South China Sea; F, H. exilis n. sp., paratype female (15.1 × 11.4 mm) (ZRC 2016.0569), South China Sea; G, H. brevipes n. sp., paratype male (7.6 × 5.9 mm) (ZRC 2016.0574), Taiwan; H, H. brevipes n. sp., holotype ovigerous female (15.0 × 10.7 mm) (NTOU), Taiwan; I, H. brevipes n. sp., paratype ovigerous female (15.4 × 13.5 mm) (ZRC 2016.0572), Taiwan.

Fig. 20. Right P5 pseudochela (propodus and dactylus) of Homologenus species. A, H. malayensis Ihle, 1912, female (16.0 × 13.9 mm) (ZRC 2016.0196), Papua New Guinea; B, H. malayensis Ihle, 1912, male (carapace width 6.2 mm, rostrum damaged) (ZRC 2016.0194), Papua New Guinea; C, H. exilis n. sp., holotype ovigerous female (13.5 × 10.4 mm) (NTOU), South China Sea; D, H. exilis n. sp., paratype female (15.1 × 11.4 mm) (ZRC 2016.0569); E, H. exilis n. sp., paratype male (10.2 × 7.4 mm) (ZRC 2016.0568), South China Sea; F, H. brevipes n. sp., holotype ovigerous female (15.0 × 10.7 mm) (NTOU), Taiwan; G, H. brevipes n. sp., paratype ovigerous female (15.4 × 13.5 mm) (ZRC 2016.0572), Taiwan; H, H. brevipes n. sp., paratype male (7.6 × 5.9 mm) (ZRC 2016.0574), Taiwan.

Fig. 21. A–C, Homologenus malayensis Ihle, 1912, male (carapace width 6.2 mm, rostrum damaged) (ZRC 2016.0194), Papua New Guinea; D–F, H. exilis n. sp., paratype male (10.2 × 7.4 mm) (ZRC 2016.0568), South China Sea; G–I, H. brevipes n. sp., paratype male (7.6 × 5.9 mm) (ZRC 2016.0574), Taiwan. A, D, G, telson and pleonal somites 5 and 6; B, E, H, pleonal somites 2–6; C, F, I, outer view of left chela.

Fig. 24. Colour in life, A–H from South China Sea; I, J from Papua New Guinea and Bismarck Sea. A, Lamoha longirostris (Chen, 1986), female (24.9 × 20.3 mm) (ZRC 2016.0555); B, Lamoha murotoensis (Sakai, 1979), male (20.8 × 18.4 mm) (ZRC 2016.0200); C, Paromola macrochira Sakai, 1961, female (16.5 × 11.4 mm) (ZRC 2016.0560); D, Paromola macrochira Sakai, 1961, female (16.3 × 11.1 mm) (ZRC 2016.0562); E, Moloha majora (Kubo, 1936), male (54.8 × 47.8 mm) (ZRC 2016.0197); F, Homolochunia gadaletae Guinot & Richer de Forges, 1995, ovigerous female (34.1 × 26.4 mm) (ZRC 2016.0198); G, Homolomania sibogae Ihle, 1912, male (15.4 × 11.3 mm) (ZRC 2016.0199); H, Paromolopsis boasi Wood-Mason, in Wood-Mason & Alcock, 1891, male (20.1 × 17.7 mm) (ZRC 2016.0565); I, Homologenus malayensis Ihle, 1912, ovigerous female (16.0 × 13.9 mm) (MNHN-IU-2015-80); J, Homologenus malayensis Ihle, 1912, ovigerous female (14.9 × 9.9 mm) (MNHN-IU-2014-8052).

Fig. 12. Homologenus malayensis Ihle, 1912. A–D, I–L, male (carapace width 6.2 mm, rostrum damaged) (ZRC 2016.0194), Papua New Guinea; E–H, female (16.0 × 13.9 mm) (ZRC 2016.0196), Papua New Guinea. A, left third maxilliped; B, dorsal view of right cheliped carpus; C, left G1; D, left G2; E–L, female left P2–P5 merus, respectively; I–L, male left P2–P5, respectively. Scales: C, D = 0.5 mm; E–L = 5.0 mm.

Fig. 11. Homologenus malayensis Ihle, 1912, female (16.0 × 13.9 mm) (ZRC 2016.0196), Papua New Guinea. A, frontal view of cephalothorax; B, rostrum, pseudorostrum and orbit; C, left third maxilliped; D, dorsal view of right cheliped carpus; E, outer view of left chela; F, posterior carapace margin and male pleonal somites 1.