Decoding the bare necessities of decapod crustacean nomenclature through the ages

Etymologies in numbers

The total dataset consisted of 22,363 entries with 11,981 unique etymologies. This count, however, differentiates between variations of the same name to ensure gender agreement with the generic name, e.g., Travancoriana granulata Pati & Sharma, 2013 vs. Engaeus granulatus Horwitz, 1990. The true number of unique etymologies will thus be slightly lower.

Across the entire time period (1758–2024), the majority of etymologies referred to the morphology of the taxa (43.3%), whilst a significant proportion also referred to people (24.2%) and geography (18.7%) (Fig. 1). Relatively infrequently used categories are ‘Culture’ and ‘Expeditions’. The ‘Other’ category appears somewhat large but perhaps was artificially inflated by our inability to accurately assign a number of, usually older, names.

Despite almost half of all etymologies referring to a morphological aspect of the species, the majority of most frequently deployed names are from different categories. The two most frequently used etymologies across the entire dataset are from the ‘Other’ category: intermedia/intermedius (used for 91 taxa) and affine/affinis (85 taxa), followed by two from the ‘Geography’ category: japonica/japonicus (81), and orientale/orientalis (70). Only the fifth most used is from ‘Morphology’: gracilis (69), followed in the top ten by crosnieri and holthuisi (‘People’, 64 each), indica/indicus (‘Geography’, 59), and the morphological terms longipes (54), inermis (53), and gracilipes (51).

At a category level, the most used etymologies for ‘People’ reads like a Who’s Who of decapod taxonomy (Table 1), with the highest number of honorifics for the late A Crosnier (1930–2021) and LB Holthuis (1921–2008), but also recognising the monumental contributions of earlier (e.g., A Alcock, 1859–1933; JG De Man, 1850–1930) as well more contemporary taxonomists (e.g., AJ Bruce, 1929–2022). Two of the highly honoured taxonomists are female, viz. MJ Rathbun (1860–1943) and D Guinot (1933–), the latter being the only living person in Table 1, testimony to her current influence on the field.

The most frequently deployed etymology in the ‘Geography’ category belongs to taxa with their type locality in Japanese waters (Table 1), whilst taxa discovered in China also feature at position seven. The others are all very broad geographical terms, e.g., Brachynotus atlanticus Forest, 1957 and Palaemonella orientalis Dana, 1852.

In terms of Ecology (Table 1) it is not surprising that terms reflecting the deeper-water, or pelagic habitat feature heavily, e.g., Stylodactylus profundus Cleva, 1990; Nectoceras pelagica Rafinesque, 1817. Given the propensity of many decapods to form symbiotic relationships with a variety of taxa, sponge- (e.g., Periclimenaeus spongicola Holthuis, 1952) and coral- (e.g., Galathea corallicola Haswell, 1882) dwelling taxa were frequently named for this relationship, whilst further derivations such as Nematopagurus spongioparticeps McLaughlin, 2004 and Galathea coralliophilus Baba & Oh, 1990 abound.

Although overall, not that frequently deployed, in ‘Culture’ all of the most frequently deployed etymologies derive from Greek mythology, many, but not all, connected to the marine realm (e.g., Alpheus neptunus Dana, 1852; Paguristes triton McLaughlin, 2008). A disproportionate number of cultural names can be attributed to individual taxonomists: for example, E Macpherson and co-authors described 27% of all cultural names, reflective of his apparent infatuation with Greek (and other) mythology. In this way, clear signals can be picked out of an individual carcinologist’s work and impact. Alongside honorific eponyms, trademark naming practices are another way taxonomists may leave their mark and legacy within their field (see also Pardos & Cepeda, 2024; Jasper, Froehlich & Carbayo, 2015).

Unsurprisingly, in the category ‘Expeditions’, a significant proportion of taxa was named for the Dutch Siboga expedition (1899–1900), largely in a series of articles in 1905–1938 by De Man, Tesch etc., which worked up the expedition’s results, e.g., Homolomannia sibogae Ihle, 1912. The collections made by the Investigator in Indian waters (e.g., Paralomis investigatoris Alcock & Anderson, 1899), as well as the Atlantic and Mediterranean collections by the Talisman are honoured in several names (e.g., Gennadas talismani Bouvier, 1906). More contemporary expeditions organised by MNHN (Paris) are also often honoured, notably the 1991 KARUBAR cruise to Indonesia (e.g., Chaceon karubar Manning, 1993) and the 2004 PANGLAO survey in the Philippines (e.g., Stereomastis panglao Ahyong & Chan, 2008).

Although there is some evidence in other groups that the usage of non-classical language (e.g., Latin, Greek) has risen through time for a variety of taxa (Heard & Mlyrnarek, 2023; Pardos & Cepeda, 2024), these continue to be a numerical minority in decapods. To give but two examples: Notosceles pepeke Dawson & Yaldwyn, 2000, a Māori derived name of a frog crab, and Hexaplax saudade Rahayu & Ng, 2014, a Portuguese word meaning a melancholic longing for something that is absent, lost or unattainable.

Homage to homer

Whilst much has been written about the humorous and inappropriate etymologies of taxa (Lalchhandama, 2014 provides a more than thorough review) across a variety of groups, in reality the vast majority of species names across all taxa are rather simple or innocuous. This is equally the case in Decapoda, with names often referring to straightforward morphological features (e.g., Sicyonia robusta Crosnier, 2003) or colour (e.g., Mithraculus ruber Stimpson, 1871) of the species, or its type locality (e.g., Metapenaeus palaestinensis Steinitz, 1932; Raymunida iranica Osawa & Safaie, 2014); see also Table 1 for further examples.

Nevertheless, a good number of whimsical, fantastical and curious etymologies exist across Decapoda, in common with all other groups studied so far.

The two shortest names, two letters as allowed by the International Code of Zoological Nomenclature (ICZN, 1999) are Zuzalpheus ul Ríos & Duffy, 2007 (now placed in Synalpheus), a Mayan word meaning ‘inside’, referring to the sponge-dwelling habitat of the species and Potamon ou Yeo & Ng, 1998 (now placed in Indochinamon), named after its type locality ‘Nam Ou’. Conversely, the longest specific epithets belong to Synalpheus hastilicrassus var. acanthitelsoniformis De Man, 1920 (junior subjective synonym of Synalpheus hastilicrassus Coutière, 1905) and Caridina pseudogracilirostris Thomas, Pillai & Pillai, 1976 (junior subjective synonym of Caridina gracilirostris De Man, 1892), each at 20 characters long.

Whimsical examples abound amongst decapod etymologies. These include Lithoscaptus doughnut Wong et al., 2023, named for the resemblance of the host’s corallites to the sugary snack, Paragiopagurus schnauzer Lemaitre, 2006, named after Patsy McLaughlin’s favourite dog breed, and Vulcanocalliax beervana Schnabel & Peart, 2024, named after a New Zealand beer festival. Tongue-in-cheek name constructs are of course not restricted to modern times, for example Lophopanopeus somaterianus Rathbun, 1930, was based on two dactyli taken from the stomach of Eider ducks (genus Somateriana Leach, 1819).

Fantastical creatures and persona are not neglected in decapod etymologies, with Harryplax severus Mendoza & Ng, 2017 (a dual reference to two main characters in JK Rowling’s ‘Harry Potter’ series) and Odontonia bagginsi De Gier & Fransen, 2018 (alluding to the Baggins family of ‘The Hobbit’ by JRR Tolkien) as examples. Other examples of popular culture (although a minority of names at 0.12% overall) are represented by, for example, Albunea groeningi Boyko, 2002, for Matt Groening, creator of the acclaimed cartoon series ‘The Simpsons’ and ‘Futurama’. Almost no decapod taxa are named for contemporary celebrities: Thor dicaprio Anker & Baeza, 2021 and Elephantis jaggeri Klotz & De Grave, 2015 are perhaps the only examples so far, despite the positive online impact such names can potentially generate (Blake et al., 2023).

Early explorers are of course honoured in a series of names, such as Synalpheus bougainvillei Coutière, 1905, as are contemporary biodiversity hunters (e.g., Pseudocoutierea wirtzi d’Udekem d’Acoz, 2001; Petrolisthes paulayi Hiller & Werding, 2016). Nobility is equally represented, e.g., Parapilumnus leopoldi Gordon, 1934 and Macrobrachium sirindhorn Naiyanetr, 2001, named for the Belgian King Leopold III and the Thai Princess Sirindhorn, respectively, in recognition of their interest in natural history. Albert I, Prince of Monaco (1889–1922) devoted much of his life and fortune to maritime pursuits, often accompanied by biologists on his yachts. In recognition, seven taxa were named in his honour, e.g., Lithodes grimaldii A. Milne-Edwards & Bouvier, 1894. A number of taxa have also been named after the Japanese Emperor Hirohito (1901–1989), e.g., Osachila imperialis Sakai, 1963; usually based on specimens collected by the Emperor himself, a renowned hydrozoan taxonomist.

Aside from the decapod taxonomists most frequently honoured with plentiful dedications (the ‘Giants on whose shoulders we stand’; Table 1), numerous others are of course also recognised, testimony to the respect they command in the community. To list but a few contemporary examples: Troglocarcinus monodi Fize & Serène, 1956; Harrovia ngi Chen & Xu, 1992; Hymenopenaeus tuerkayi Crosnier, 1995; Dactylonia franseni Bruce, 2003; and Tomopaguropsis rahayuae Jung, Lemaitre & Kim, 2017. Equally, many of those who went before have also been honoured, e.g., Herbstia ortmanni Balss, 1924; Lissoporcellana miyakei Haig, 1981 and Nikoides danae Paulson, 1875.

Guedes et al. (2023) identified a significant proportion of African vertebrates named for individuals from the European colonial period. Though we did not discriminate by geographic origin of the species, across all decapod etymologies such constructs are apparently quite rare. Amongst the examples we were able to identify are Potamon rafflesi Roux, 1936 named for British colonial official Sir Stamford Raffles, Platyxanthus balboai Garth, 1940 after the conquistador Vasco Núñez de Balboa, and more recently, Lysmata napoleoni De Grave & Anker, 2018, for the French Emperor exiled to St. Helena.

Somewhat peculiar are etymologies in which the name refers to colloquial or indigenous names for the taxon in question. For example, Linnaeus (1758) named Cancer crangon, the European brown shrimp, simply after an ancient Greek word for shrimp. Other examples are Cancer saratan Forskål, 1775, from the Arabic word meaning crab and more recently Cambarellus moi Pedraza-Lara, Ortiz-Herrera & Jones, 2021, meaning crayfish in a local Mexican tribal language. Such pseudo-tautonyms are a way of bringing forth the language and culture of native peoples who have long known these species, and thus avoiding a complete westernisation of biodiversity records: the case for such a practice was made by Gillman & Wright (2020).

Temporal trends

A significant interaction exists between the year of description and etymology categories, as defined by proportional usage through time (Fig. 2). During the ‘Wunderkammer’ era (1789–1836), morphological etymologies dominate throughout, although declining somewhat in the later years, when etymologies based on people play a significant role. During the ‘Victorian’ era a steep decline in morphology-based etymologies can be observed, concomitant with a rise in etymologies based on people and geography; this trend continues into the ‘World in turmoil’ era, although less pronounced. During the ‘Sputnik’ era and into the ‘New taxonomy’ era matters stabilise significantly and morphology-, people- and geography-based etymologies each account for roughly 25–30% of all names. All other coded categories do not show any significant temporal trend, presumably linked to their modest contribution. A very similar temporal trend was observed for spider names, with a general decline of morphology-inspired names post-1900 and an increase in etymologies based on people and geography since then (Mammola et al., 2023). A notable difference is the predominance of geographically based etymologies in spiders in the last 10 years (Mammola et al., 2023), whilst in Decapoda morphology still dominates; presumably a taxon-specific fashion.

Looking at individual frequency curves (Fig. 3), it is again clear morphology-based etymologies (Fig. 3A) dominated during the ‘Wunderkammer’ and ‘Victorian’ eras, suffering a sharp decline during the ‘World in turmoil’ era. However, they regained their importance post-1955 and continue to be widely deployed in current taxonomy. Geography-based etymologies show a general increase in usage throughout the eras (Fig. 3B), with some notable peaks. Yokoya (1933), in an important monograph on Japanese decapods, named 22 taxa japonica/us and nipponensis, amongst other geographical names. Other authors (e.g., Balss (1933), Monod (1933), Rathbun (1933)) that year also liberally used geographical etymologies, with a further 34 taxa, causing an overall spike in the data. Post 1980, geographically inspired names gained importance, in many years being 25–30% of all etymologies.

An early employer of eponyms was H Milne Edwards, who honoured numerous scientists in a series of works around the 1850s, notably H. Milne Edwards (1853) in which 39 such names appear (Fig. 3C). The period 1902–1905 also sees a relatively large number of taxa honouring other scientists, through the work of De Man, Rathbun, Nobili, Alcock, Coutière and contemporaries. From the 1980s onwards honouring fellow scientists, including collectors of the type material, became relatively commonplace and in many years amounts to 25–30% of all names. If the current trend of festschrifts continues, such honorifics can be forecasted to maintain numbers, especially in localised spikes. Although there are several examples of taxa named after ‘Other People’ (i.e., non-scientists and/or uninvolved in the collecting process) early on, e.g., Ilia mariannae Herklots, 1852, such name constructs only really become popularised since the 1950s, and continued to gain popularity up to the present day, although in any given year they only comprise a minor proportion (1.6% across the entire dataset).

Etymologies using references to ‘Expeditions’, ‘Ecology’ and ‘Culture’ have always been a minor component of the naming process (Figs. 1, 2). These categories show a general upward trend in frequency through the decades (Figs. 3D–3F), but proportionately have remained fairly static (Fig. 2), suggesting the increase in occurrence is more linked to the general increase in taxon descriptions (see De Grave et al., 2023) rather than an underlying temporal trend in naming practices.

Gender imbalance

In carrying out a gender analysis into eponymic naming practices of scientists, it is necessary to disentangle an expected imbalance (product and reflection of the gender divide in the wider field due to societal factors beyond the scope of this study) from any potential active bias in the naming practices (such as male scientists amassing more eponyms per individual than their female counterparts). The number of female scientists honoured throughout the entire 1758–2024 period was 263 (11.7%) compared to 1986 males. A similar disparity has been observed in helminths (18.6% after females, see Poulin, McDougall & Presswell, 2022) and molluscs (10.6%, see Vendetti, 2022). Although this gender disparity is stark, this inequity can largely be explained by historically few women studying Decapoda at the level of professional researcher, museum curator or professor, a result of barriers which only started to be removed in the late 20^th Century. When the dataset was reduced to 1958 onwards to focus on contemporary trends, the gender imbalance persisted but at a slightly diluted rate: 229 females (16.9%) compared to 1,123 males. This shift corroborates a positive inclusivity trend observed by Sangster (2025) among bird eponyms over a similar timescale, and with still a little way to go approaches known figures of the actual proportion of women within taxonomy, which vary depending on sample group between 17–28% (House of Lords, 2008; Salvador et al., 2022, respectively). The particular recognition of MJ Rathbun (see Table 1), who for temporal context was the Smithsonian’s first full-time paid female scientist, might indicate that where historically present, women’s contributions are indeed eponymised.

Regarding gender bias, an analysis of eponym counts per individual found almost no bias present in the actual naming process, with scientists, once honoured, having a near equal number of taxa named after them irrespective of gender (Fig. 4). Although a minor skew is present with only 18% of females being honoured more than once (vs. 26% of males), this largely disappears with higher numbers of honorifics, with 11% of females having been honoured more than twice (vs. 13% of males).

Caveats

The temporal trends identified herein for decapod etymologies are similar to those identified for helminths (Poulin, McDougall & Presswell, 2022), spiders (Mammola et al., 2023), kinorhynchs (Pardos & Cepeda, 2024) and echinoderms (Kazanidis, 2024) and can thus be considered a true reflection of changing taxonomic naming fashions. Deducing etymologies is, however, fraught with difficulty, as unless the etymology is specified (uncommon pre-1950), an a posteriori interpretation of the author’s intention must be carried out. For example, unrecorded anecdotal epithets such as Notiax santarita Thatje, 2000, named for the wine enjoyed on the cruise during which the species was collected (S Thatje, 2025, personal communication), would remain obscure to us if the describer were uncontactable. Doubtless, many such gems are lost to history. For most etymologies related to morphology or geography, this remains straightforward, however in the other categories difficulties can be encountered. For example, Sesarma calypso De Man, 1895–1898 is herein interpreted to be named after one of the Greek nymphs, in contrast with Synalpheus calypso Ashrafi, 2024 which is stated in the etymology (Ashrafi, 2024) to have its name derived from Jacques-Yves Cousteau’s vessel.

This becomes an acute problem when investigating eponyms, as on occasion authors use an oblique reference to the person being honoured, e.g., Helice epicure Ng, Naruse & Shih, 2018, named for the late Michael Türkay, a food connoisseur as well as a brilliant decapod taxonomist. Equally, authors sometimes utilise different parts of the honouree’s name, e.g., Pagurus alaini Komai, 1998 and Alpheus alaincrosnieri Anker, 2020, both of course named for A Crosnier. As discussed already, in pursuing the gender analysis, every reasonable effort was made to disambiguate these variations, thereby revealing the true number of honorific species names per individual. As a result, the highest number of honorifics are for Lipke Holthuis (85 names), a testament to his enduring legacy and influence on decapod taxonomy. Equally, a further 12 names honour Alain Crosnier, totalling 76 taxa, evidence of his influence on decapod taxonomy. This equally applies to Danièle Guinot, who in addition to the 26 ‘guinotae’ (Table 1) is honoured in a further 14 names, e.g., Dicranodromia danielae Ng & McLay, 2005.