Inachidae

Guinot, Danièle, 2012, Remarks on Inachoididae Dana, 1851, with the description of a new genus and the resurrection of Stenorhynchinae Dana, 1851, and recognition of the inachid subfamily Podochelinae Neumann, 1878 (Crustacea, Decapoda, Brachyura, Majoidea), Zootaxa 3416, pp. 22-40 : 34-35

Remarks on Inachidae and the status of some American inachid genera

As constituted (Ng et al. 2008: 110), the large family Inachidae , is heterogeneous, presently not subdivided into subfamilies. In contrast, Števċiċ (2005) recognised 17 tribes in his subfamily Inachinae , which he included in Majidae . A reappraisal of Inachidae is needed, and it is suggested that at least some of the subfamilies that were recognised in the past ( Dana 1851; Miers 1879; see also Young 1900) should be reinstated. For example, a number of American genera (such as Podochela Stimpson 1860 , Metoporhaphis Stimpson, 1860 , Anomalopus Stimpson, 1871 , and many others see below) traditionally placed in Inachidae have exposed pleurites like inachoidids but the pattern of their exposed pleurites is not equivalent to the Inachoididae pattern. Other features also distinguish them from typical inachoidids. Furthermore these American genera do not conform to the Inachidae as defined by its type genus Inachus Weber, 1795 , diagnosed by the characters of its type species Inachus phalangium (Fabricius, 1775) , from the eastern Atlantic Ocean ( Norway to West Africa and Cape Verde Islands) and the Mediterranean Sea. Some pleurites are exposed in inachids but to a much lesser extent than in inachoidids, and the pleurites remain detached from the carapace edge so that the carapace does not rest in a “setting gutter” as in Inachoididae but instead lies on a shallow groove at the surface of exposed pleurites. These exposed pleural sclerites are always narrow, although they vary somewhat among inachid taxa (from 5–7, 6 – 8 or only 6 and 7, the sclerite 8 being often small or sometimes partially encircling the arthrodial cavity of P 5). Moreover, in contrast to Inachoididae , the first abdominal somite of Inachidae is not “integrated” as a part of the carapace. Nevertheless, at least some of the representatives of these two families are considered close, in contradiction to Števċiċ (2005), who included Inachinae in Majidae and distinguished Inachoididae , at the same rank as his Majidae .

It is surprising how the exposure of the posterior pleurites has been overlooked by most carcinologists, who have only gone as far as describing the carapace as “broadly expanded posteriorly at the bases of the ambulatory feet” when describing Podochela riisei Stimpson, 1860 ( Stimpson 1860: 196, pl. 2, fig. 6; see Young 1900: 16, as “ reisei ”). A group of supposed American inachids (see below) shows a partial exposure of pleurites 6–8 in the form of narrow, elongated plates between the carapace edge and the coxae of the last pereopods (P 3 –P 5), with pleurite 8 sometimes exposed to a lesser extent than preceding pleurites. In contrast to Inachoididae (where the exposed pleurites 5–8 are larger and equivalent, giving the appearance of being a part of carapace), in these American genera each exposed pleurite appears as an additional, proximal article of the pereopod, in particular at P 3 and P 4 levels. Additionally, a developed membrane often separates the exposed pleurite from the coxa of the pereopod to which it is articulated. Furthermore, the first abdominal somites, although dorsally exposed, are not “integrated” into the carapace outline as in the Inachoididae .

These American genera with exposed pleurites need to be thoroughly revised to determine their taxonomical status with respect to both Inachidae and Inachoididae . Some genera are tentatively grouped as follows.

Podochelinae Neumann, 1878. It is suggested to group the following taxa under the nomen Podochelinae Neumann, 1878 ( Neumann 1878: 13; see Davie 2002: 280) the following taxa: Podochela Stimpson 1860 (P. g ro s - sipes Stimpson, 1860, as type species by subsequent designation by Miers 1879); Coryrhynchus Kingsley, 1879 ( Podonema riisei Stimpson, 1860 , as type species by subsequent designation by Miers 1879); Ericerodes Rathbun, 1897 ( Ericerus latimanus Rathbun, 1894 , as type species by monotypy); Anisonotus A. Milne-Edwards, 1879 ( Anisonotus curvirostris A. Milne-Edwards, 1879 , as type species by monotypy) (see Coelho 2006). Several species of these genera have been examined: Coryrhynchus riisei (MNHN-B 4402), C. lobifrons (Rathbun, 1894) (MNHN- B 20836 ), Ericerodes gracilipes ( Stimpson, 1871) (MNHN-B 20484), E. hemphillii (Lockington, 1877) (MNHN- B 20805 ; MNHN-B 20487), Podochela grossipes Stimpson, 1860 (MNHN-B 557), P. macrodera Stimpson, 1860 (MNHN-B 4401), and Anisonotus curvirostris (MNHN-B 4403).

This group of crabs with a narrow carapace shares the following pattern: a quadrate first abdominal somite (Hendrickx 1987: fig. 1 A, B; Coehlo 2006: figs. 8, 11, 12, 15, 16, 19); a particularly wide thoracic sternum (Coehlo 2006: figs. 7, 10, 14), sometimes in the form of raised plates, separated by deep depressions ( A. Milne-Edwards 1873 –1880: pl. 34, fig. 1 a, pl. 36, fig. 3 d); the P 1 insertion points close to each other (Coehlo 2006: figs. 7, 10, 14); and a narrow junction of the thoracic sternum with the pterygostome. These characters need to be verified in all species of each genus. Podochelinae is an available nomen for this group, having not been used by carcinologists or by Coelho (2006) in his revision of Podochela and allied genera. The podochelines, which are small crabs with long legs and called “neck crabs” or “frilly neck crab”, decorate their bodies using recurved setae on the rostrum, carapace and legs.

Metoporhaphis Stimpson, 1860 ( Leptopodia calcarata Say, 1818 , as type species by monotypy) probably belongs in Podochelinae. A junior synonym of M. calcarata , M. forficulatus A. Milne-Edwards, 1878 (A. Milne- Edwards 1873 –1880: pl. 31, fig. 3), has been examined (holotype, “Golfe du Mexique ”, MNHN-B 4396). However, because it is a female in a dry and poor condition, some doubt about the status of M. calcarata (see Rathbun 1925: 19, pls. 6, 7; Garth 1958: 39) persists. A molecular phylogeny using three loci (16 S, COI, and 28 S) from 37 majoid species by Hultgren & Stachowicz (2008: 993, 994, table 3) supported several relationships predicted from larval morphology, and a notworthy result is the grouping in the same clade of Ericerodes hemphillii (as Podochela ) and M. calcarata .

Anomalopodinae Stimpson, 1871. This group of other small American inachids show a narrow, hardly visible exposure of pleurites. The type genus Anomalopus Stimpson, 1871 ( Stimpson 1871: 124) ( Anomalopus furcillatus Stimpson, 1871 , as type species by monotypy), was pre-occupied by Anomalopus Duméril, 1851 [Reptilia] and replaced by Anomalothir Miers, 1879 ( Miers 1879: 648) . Anomalopodinae Stimpson, 1871, a replacement nomen for Anomalopinae (note that “flashlight” or “lantern” fishes constitute the family Anomalopidae in the subclass Actinopterygii, order Bercyformes), was not used by subsequent authors such as Rathbun (1925) and Garth (1958). The subfamily was resurrected by Coelho (1999 a: 58; 1999 b: 153, 156) as containing Anomalothir and Eucinetops Stimpson, 1860 ( Eucinetops lucasii Stimpson, 1860 , as type species by monotypy). Anomalopodinae was not mentioned in papers where subfamilial levels were not indicated (e.g., Almeida et al. 2007 b; Coelho et al. 2008; Almeida et al. 2008), but Števċiċ (2005: 95) recognised a tribe Anomalopini.

In Anomalothir furcillatus ( Stimpson, 1871) (MNHN-B 3969; MNHN-B 17810) the exposure of pleurites is weak, the sclerites at the level of pleurites 5–7 being so narrow that they are not visible in the figures of the species ( A. Milne-Edwards 1873 –1880: pl. 35, fig. 4; Rathbun 1925: pl. 8, fig. 2, pl. 9, fig. 2, pl. 206; Coelho 1999 b: fig. 2 a), the first two abdominal somites are dorsally exposed at least in females, the thoracic sternum is narrow, and sternal extensions seem to be present between the P 2 and P 3 and between the P 3 and P 4.

Eucinetops (see Hendrickx 1999: 15, figs. 7–12), which was included in Anomalopodinae by Coelho (1999 b: 153, 157, 159) despite several differentiating features, could not be examined. This inclusion reveals, however, to be doubtful, the differences between the two genera being numerous (shape of carapace, rostrum, cephalic appendages, epistome, pereopods). The nomen Eucinetopini, established by Števċiċ (2005: 98) for an inachine tribe with Eucinetops as type genus, may remain valid for Eucinetops at a subfamilial level, as Eucinetopinae Števċiċ, 2005.

As a preliminary conclusion based on the observations made in this contribution, it would appear that both Inachidae and Inachoidididae must be regarded as comprising several subfamilies: Inachidae , with at least Inachinae , Podochelinae, Anomalopodinae (and probably also Eucinetopinae); Inachoidididae, with at least Inachoidinae, Stenorhynchinae, and perhaps also Salaciinae.