Metriaclima Stauffer, Bowers, Kellogg & McKaye 1997
Creators: name: Scharpf, Christopher
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Perciformes
Cichlidae
Metriaclima

description: Metriaclima vs. Maylandia: a critical review of the debate
Shortly after Metriaclima was proposed as a replacement for Maylandia, articles began to appear in aquarium publications and online both for and against the new name. Ichthyologist Lothar Seegers (1998) defended Maylandia, saying that the description of Ps. greshakei, clearly identified as the type species of Maylandia, provides sufficient information to define Maylandia as well, but also noted that additional distinguishing information is provided elsewhere in the paper. Seegers also said that Meyer and Foerster’s description of Maylandia fulfills ICZN Articles 13a, b and c regarding the availability of names published after 1930, but there is no 13c in the 1964 Code. It appears that Seegers is referring to the third edition of the Code, published and in effect in 1985, the year after Maylandia was proposed. As we shall see, others have made a similar mistake. Ichthyologist Isaäc J. H. Isbrücker (1998) appends Seegers’ article with a brief note saying that Metriaclima is a junior synonym of Maylandia and that Stauffer et al. ’s claim that Maylandia is a nomen nudum is “nicht haltbar” (not tenable), but offers no evidence or analysis in support of his counter-claim. Aquarist Wolfgang Staeck (1998) says that while Meyer and Foerster do not explicitly use the term “diagnosis” in their description, they do mention special features of the jaw and pharyngeal dentition and the black vertical stripes as diagnostic characters that distinguish Maylandia from other members of Pseudotropheus. Aquarist Erwin Schraml (1998) says the nomen nudum designation is “not supported by examination of the description of Maylandia,” because Meyer and Foerster (1984) “refer to explicit differences in the dentition and melanin patterns of their subgenus compared to those of the type species of Pseudotropheus (Ps. williamsi).” Another aquarist, Alfred Ufermann (2001), reproduces Meyer and Foerster’s description, highlighting the phrases that purport to distinguish Maylandia from Pseudotropheus. He concludes that Maylandia “a clairement priorité” (“clearly has priority”) over Metriaclima. Eschmeyer’s Catalog of Fishes cites Ufermann (2001) as evidence for the availability of Maylandia. Two years later, cichlid taxonomist Michael Oliver (2003), at his “Cichlid Fishes of Lake Malaŵi, Africa” website, demonstrated that Meyer and Foerster’s description satisfied all the requirements of availablity as stipulated in Article 13 of the ICZN Code, but cited the 1999 edition, whose Article 13 does not significantly differ from the version published in 1964.
The first, and thus far only, defense of Maylandia to appear in a peer-reviewed journal was by the two ichthyologists who prepared Meyer and Foerster’s paper for publication, Bruno Condé (the journal’s editor), and Jacques Géry (who “refereed” the manuscript). Condé and Géry (1999), writing in the same journal in which the original paper appeared, reiterated the diagnostic characters as given above, and suggested that Stauffer et al. (1997) either did not read or understand the original French description, or perhaps relied on an inadvertent mention of Maylandia that appeared in a cichlid enthusiast magazine before the taxon was officially proposed. I have not been able to locate this mention, although another species of the genus, Ps. (now Maylandia) hajomaylandi, may have been involved; see below. Condé and Géry (1999) also cite Art. 13c, which they claim allows Maylandia to be characterized by its type species: “The combined description or definition of a new nominal genus and a single included new nominal species, if marked by ‘n.g., n.sp.’ or an equivalent expression, is deemed to confer availability on each name under Article 13a (i); the type species of the genus is fixed by monotypy [Art. 68d].” This argument can be dismissed for two reasons. Art. 13c refers to monotypic genus-level names, whereas Maylandia is proposed to contain five species. In addition, repeating the mistake of Seegers (1998), Art. 13c debuted in the (1985) edition of the Code and does not apply to taxa published in 1984.
The most vocal critics of Maylandia are Lake Malawi cichlid expert Ad Konings and Dutch aquarist Martin Geerts, who, between the two of them, have authored or co-authored five articles for cichlid hobbyist publications and websites. Konings (1998) briefly mentions that Maylandia is a nomen nudum because “no characters were given that future taxonomist [sic] could use in sorting their species.” In February 1998, Geerts sided with Metriaclima in his bimonthly “Cichlidesque” column in the Dutch magazine Cichlidae, expressing doubts that one could find “something resembling a description” (translation) of Maylandia in Meyer and Foerster’s text. He takes issue with the fact that Meyer and Foerster, instead of explicitly stating how Maylandia differs from Pseudotropheus (a direct subgenus-to-subgenus comparison), explain how Maylandia differs from the type species of Pseudotropheus, Ps. williamsi. In so doing, Geerts writes, Meyer and Foerster are “apparently assuming that they have already sufficiently described Ps. greshakei, the type species of Maylandia, on the preceding pages, so that there would be no further need for a description of this subgenus” (translation). In other words, had Meyer and Foerster repeated diagnostic characters from their description of Ps. greshakei within their Maylandia description, then Geerts may have been satisified that Maylandia was sufficiently described. Nevertheless, Meyer and Foerster’s approach, though less than ideal, does not violate Article 13 of the 1964 edition of the ICZN, which states that new taxa must be “accompanied by a statement that purports to give characters differentiating the taxon.” The Code does not dictate where in the description that differentiating statement must be given. As summarized in Table 1, Meyer and Foerster provided several characters purported to distinguish Maylandia from Pseudotropheus. These characters are not as neatly summarized as they are in Table 1, but they are clearly stated in Meyer and Foerster’s text if one takes the time to find them. Geerts concludes his comments by saying, perhaps with tongue-in-cheek, “It seems to me that it would be advisable to follow Stauffer and his colleagues, if only to prevent us from having another species that has to be called Maylandia hajomaylandi ” (translation), referring to Pseudotropheus (Maylandia) hajomaylandi, described later in 1984.
Geerts expanded his argument against Maylandia in his April 1999 “Cichlidesque” column. This is the first presentation of the basic argument that others, including Stauffer, the lead author of the 1997 paper dismissing Maylandia, would reference in subsequent publications. The basic argument is this: Meyer and Foerster describe Ps. greshakei and provide diagnostic characters for a group of Pseudotropheus species called the “zebra complex,” but do not explicitly include Maylandia within that group; since there is no seeming description of Maylandia, it is therefore a nomen nudum. As stated by Geerts (1999), Meyer and Foerster “forgot to include their type species [Ps. greshakei] in the list of species that they believed to be part of the zebra complex” (translation).Actually, Meyer and Foerster forgot no such thing. Geerts apparently overlooked the German abstract, which states: “ Pseudotropheus greshakei (loc. typ. Makokola, Lake Malawi) is described, illustrated and compared with Ps. aurora, Ps. lombardoi, Ps. livingstonii and Ps. zebra. All of the taxa mentioned are assigned to the new subgenus Maylandia ” (translation). Geerts also apparently overlooked the fact that Meyer and Foerster recorded meristic differences (eye diameter, snout length, interorbital space, gill raker counts) for all five species in the “Affinities” section of their Ps. greshakei description. The number of gill rakers on the lower segment of the first gill arch of Ps. greshakei, they remark, “are among the lowest numbers of the species of the subgenus Maylandia ” (translation), clearly establishing that they include all five species in Maylandia. Geerts’ focus on the “zebra complex” is peculiar considering that Meyer and Foerster mention that term (“complexe de zebra ”) just once in their paper, as an informal collective term for four previously described species, Ps. aurora, Ps. lombardoi, Ps. livingstonii and Ps. zebra, that possess vertical bars or stripes. (Note: Ps. livingstonii is no longer considered a member of Maylandia.)
Later in 1999, the Metriaclima vs. Maylandia debate made its first appearance in the pages of an American magazine, Cichlid News, published by Ad Konings. (A concurrent German edition was also published.) Written by Konings and Geerts, the article largely repeated what Geerts had said in 1998 but added several new details. For example, Konings and Geerts claim that Meyer and Foerster’s original “description” (they place the word in quotes to signify that it fails in this regard) contains “not even a single character!” This is a baffling statement to make considering the characters summarized in Table 1. Konings and Geerts then elaborate on Geerts’ 1999 claim that Meyer and Foerster describe the zebra complex but not Maylandia: “They only mention that Ps. greshakei resembles them [the zebra complex], but so do many other species; but for all we know, Ps. greshakei may resemble other species even more. If they would have taken Ps. zebra (or any of the four species they mentioned) as the type species of Maylandia, then they would have diagnosed the subgenus correctly. As it stands now, there is a ‘zebra complex’ with some sort of diagnosis, but no formal name, and there is a name (Maylandia) without a formal description, i.e., a so-called nomen nudum.” Konings and Geerts acknowledge that Meyer and Foerster “mention” that the zebra complex “should be included” in Maylandia but dismiss the statement because the authors “don’t give reasons or grounds” for the inclusion. Konings and Geerts conclude that the zebra complex cannot belong in Maylandia because “there has been no description of Maylandia,” although, as explained above, one can assemble a description of Maylandia from statements given in the Ps. greshakei and Maylandia sections of the paper. It appears that Konings and Geerts, and presumably Stauffer et al. (1997) as well, reject the unconventional presentation of Meyer and Foerster’s diagnostic information rather than the information itself. But the ICZN Code judges on content, not style. A final note about this article: Despite their conclusion that Maylandia is a nomen nudum, Konings and Geerts state that the name is “technically available for use in naming a new taxon.” Their use of the word “available” requires explanation. They are not saying that the name/author combination “ Maylandia Meyer & Foerster 1984 ” is nomenclaturally available, in which case it would have priority over Metriaclima. They are merely stating that the word “ Maylandia ” remains available as a potential name for the taxon. Konings and Geerts state that Stauffer et al. (1997) could have used “ Maylandia ” but chose to coin a new name instead.
Geerts’ articles caught the ire of ichthyologist Sven Kullander. In a 14 February 1999 post to the now-defunct Cichlid Systematics Discussion List, Kullander chided Geerts for publishing “nomenclatural statements in aquarium magazines of near-zero circulation among professional systematists” that neither he nor anyone he knows has seen. “Why not leave the choice to scientists trained in nomenclature,” he adds, “or refer to Eschmeyer’s Catalog of Fishes, which also lists Maylandia as available.” It is unclear how ECoF listed Maylandia in February 1999. Kullander then defends Meyer and Foerster’s paper (italics added): “There is nothing in the context of the M&F paper to preclude the conclusion that they are describing a new genus with P. greshakei as the type species and also including P. zebra and some more; and there is no doubt whatsoever what are the characters of the new genus and how to tell it apart from P. williamsi.”
Apparently undeterred by Kullander’s pronouncements, Geerts published another article defending Metriaclima. Writing in the October 2002 issue of Konings’ Cichlid News magazine, Geerts doubles down on his previous argument that Meyer and Foerster describe the zebra complex but not Maylandia. As proof, Geerts focuses on one sentence in the original description: “Nous suggérons que ce complexe de zebra soit inclus dans le sousgenre Maylandia. ” (“We suggest [propose] that this zebra complex be included in the subgenus Maylandia.”) According to Geerts, this statement “leads unequivocally to the following two conclusions: (1) the zebra complex, not the subgenus Maylandia, has been described; and (2) this zebra complex has to be included in the subgenus Maylandia, which means that this complex as such is only a part of that subgenus.” Conclusion #1 is incorrect. Meyer and Foerster do not describe a “zebra complex”; they simply describe how other species of Pseudotropheus, informally and collectively known as the “zebra complex,” resemble (i.e., share characters with) Ps. greshakei but differ from Ps. williamsi. These shared characters—“internal rows of teeth less regular and, at least in adults, comprising many unicuspids, the pharyngeal teeth thin and very closely spaced posteriorly, and the melanic pattern of the body forming more or less conspicuous vertical bars” (translation)—are unambigously stated by Meyer and Foerster. All told, the “zebra ” species are sufficiently similar to the new species Ps. greshakei to be placed with it in the new subgenus Maylandia. The meaning of Conclusion #2—about the zebra complex being “only a part” of Maylandia —is unclear and has no bearing on the availability of the new taxa being proposed. Geerts then concludes his argument: “To make matters short, from the paper of Meyer and Foerster it cannot be inferred how the subgenus Maylandia is characterized, nor can we know what character(s) this subgenus has in common with its type species, Ps. greshakei or what features this type species shares with the zebra-complex. All we know is that Ps. greshakei resembles the ‘other species’, but a resemblance is not a distinguishing character. Therefore it can only be concluded that Maylandia was not properly described, which means that this name is nothing but a nomen nudum.” Suffice it to say, Geerts’ reading of Meyer and Foerster’s text is quite the opposite of mine. I see the information needed to characterize Maylandia (Table 1). I can extract diagnostic information from the description of Ps. greshakei and apply it to the subgenus proposed to house it. And it’s abundantly clear to me why Meyer and Foerster combine Ps. greshakei and four other species based on their resemblance, i.e., the shared characters they possess.
In 2005, Ad Konings weighed in with his own analysis of the debate, published online at the Cichlid Room Companion website. Konings stated that Meyer and Foerster’s description of Maylandia does not comply with Article 13a of the 1964 Code. Per Article 13a, “To be available, every new scientific name [except for replacement names] published after 1930 must … [be] accompanied by a description or definition that states in words characters that are purported to differentiate the taxon” (or else be indicated to a previous work, which does not apply here). According to Konings, the Maylandia description does not comply with Article 13a because “there is no sentence that states in words the difference between Maylandia and the subgenus Pseudotropheus or the difference between Maylandia and all other (sub)genera. There is a section in which characters of a single species, P. williamsi, are mentioned but none that gives characters of Maylandia. Logically this automatically invalidates Maylandia because subsequent authors do not know what characters to look for to decide to place a species in Maylandia.” Konings also states that characters that are purported to differentiate the taxon cannot be “deducted” from the text. By “deducted” I presume he means “deduced” or “inferred.” Whatever his meaning, there is no such stipulation in any edition of the ICZN Code.
Although Meyer and Foerster did not provide an unambiguous declarative statement about what they believe differentiates Maylandia from Pseudotropheus, reading the entire description and cross-referencing information from separate passages makes clear that there are several “differentiating characters” (Table 1). Granted, Meyer and Foerster’s presentation of the diagnostic data is not the simplest, most direct way of differentiating the subgenus. Indeed, I would say it is clumsily presented. But the content is there if you make the effort to piece it together.
In 2009, aquarist Erwin Schraml penned a thorough analysis of the Metriaclima vs. Maylandia debate in his self-published (but now defunct) online journal eggspots (in concurrent German and English editions). His review of the literature closely mirrors the one presented here, and his conclusion is the same but perhaps more bluntly stated: The reasons why Stauffer, Konings and Geerts “obstinately assert” that Meyer and Foerster described the zebra complex instead of Maylandia is, Schraml writes, “quite beyond my comprehension.” Schraml also noted, as did Konings and Geerts (1999), that Stauffer et al. (1997) could have redescribed Maylandia rather than replacing it, thus avoiding the subsequent controversy. Schraml suggested the possibility that Maylandia was renamed for “personal reasons” having to do with Hans J. Mayland, the cichlid enthusiast and aquarium-fish author for whom Maylandia is named. Kullander appears to allude to something similiar in his 1999 Cichlid-L post, enigmatically stating that priority should always be given to available names “no matter … how much I could hate the person in whose honor it was given.” According to Schraml, Mayland published the manuscript names of several new catfish species in an aquarium publication, creating nomina nuda and forcing their author to rush preliminary descriptions (Weber, 1991). In addition, Schraml recounted a “persistent rumour” that Mayland, under a pseudonym, had published an available description of Pseudotropheus (Maylandia) hajomaylandi, also named in his honor, in an aquarium book before the official description by Meyer and Schartl (1984) had appeared. However, Schraml presented no evidence that “personal reasons” had any bearing on Stauffer et al. (1997) replacing Maylandia with Metriaclima. Schraml concluded his article by leaving the door open to publishing an opposing viewpoint in his journal. Two issues later, cichlid aquarist Mary Bailey did just that.
Bailey (2010) begins her defense of Metriaclima with a critical interpretation of the verb “differentiate” from Article 13 of the ICZN Code. Unfortunately, as others did before her, she cites the third (1985) rather than second (1964) edition, although the language is nearly the same. Article 13a(i) of the 1964 edition says names published after 1930 must be “accompanied by a statement that purports to give characters differentiating the taxon,” whereas the 1985 edition says names must be “accompanied by a description or definition that states in words characters that are purported to differentiate the taxon.” Bailey says that “differentiate” in the context of new-taxa descriptions in zoology means “define” rather than “differentiate from.” As she explains it, to “differentiate” is to explain how one taxon differs from another (e.g., Maylandia from Pseudotropheus); to “define,” however, is to explain how a taxon differs “from ALL other similar taxa, not just one” (e.g., other closely-related mbuna genera and subgenera). In order to accomplish this, Bailey says, the “description MUST provide an unequivocal list of characters that together define that taxon and no other.” Meyer and Foerster’s “alleged” description of Maylandia fails in this regard. In fact, she states, “very few of the people who support Maylandia … seem to appreciate this semantic nicety …”. Bailey’s argument would only have merit if the 1964 Code’s definition of “define” matches her own. It does not. According to the Code’s glossary appendix (not part of the official or legislative text of the Code), a definition is “A statement of the characters that distinguish a taxon.” Indeed, if Bailey’s narrow interpretation of Article 13 were required to be followed, then many currently accepted senior synonyms would have to be abandoned in favor of more recent names. In addition, since Meyer and Foerster proposed Maylandia as a subgenus of Pseudotropheus, it makes sense that they would confine their differentiation to within the genus and not expand it to include other mbuna genera.
A few paragraphs later, Bailey seems to broaden, if not contradict, her narrow interpretation of Article 13 when she addresses the inclusion of the verb “purported.” “The Code,” she says, “cannot reasonably require that the description of a taxon does define it unequivocally, as a biologist can work only with the information currently available, which may not be complete. Hence biologists are merely required to provide what they believe to be a valid definition.” Bailey now claims that Meyer and Foerster themselves “immediately question” the validity of Maylandia “on the basis of information that was available but which they hadn’t properly considered.” Her evidence is that Meyer and Foerster “aren’t even sure if this complex does belong in Maylandia, they only suggest its inclusion, they don’t actually state it is to be included.” But, as mentioned above, Meyer and Foerster do in fact state that Ps. greshakei and the zebra complex belong in Maylandia in the German abstract. Here Bailey pivots to a new argument: Abstracts don’t count because they are of “dubious taxonomic validity.” I disagree. The abstract is still part of the publication and, in this case, confirms the authors’ poorly stated intentions in the text that follows.
Bailey (2010) concludes her article with a diatribe of sorts, stating that proponents of Metriaclima “have been obliged to use Maylandia in order to have their work published, as the editors of some scientific journals and some peer-reviewers are stating that Metriaclima is invalid because Fishbase or some noted taxonomist has plumped for Maylandia.” She offers no examples or evidence in support of this claim. Nor does she mention Eschmeyer’s Catalog of Fishes, which treats Metriaclima as a junior synonym of Maylandia and is widely used by editors and peer-reviewers as an authoritative source on nomenclatural matters. Bailey continued: “One thing must be made clear—no organisation such as Fishbase, no institution, and no individual such as an editor or peer-reviewer has the right to pre-empt the role of the ICZN in ruling on nomenclatural disputes. I can only deplore such attempts to impose a personal, editorial, or institutional viewpoint on the freedom of every author to decide for him- or herself which name to follow until a ruling is made by the ICZN.” As of this writing, the ICZN has not been petitioned to suppress Maylandia as a nomen nudum.
Jay Stauffer, the lead author of the paper that declared Maylandia as a nomen nudum, has added little to the debate. In Kellogg and Stauffer (1998) and Stauffer and Kellogg (2002), he repeated the original 1997 claim that Maylandia was not accompanied by either a diagnosis or a description, but again did not elaborate beyond that statement. In Stauffer and McKaye (2001), he did not mention the nomen nudum status. Instead, he put forth a different explanation for the replacement name, saying that Meyer and Foerster’s description of Maylandia was “not adequate to include all of the proposed members of Metriaclima, thus, Metriaclima was proposed as a new generic name complete with a full description” and now “has priority and is the currently accepted name.” But the inadequacy of Meyer and Foerster’s description does not necessitate a replacement name; Stauffer et al. (1997) could have retained the name and published a redescription. In Stauffer et al. (2016), he cited and repeated the arguments put forth by Konings and Geerts. His defense of Metriaclima is quoted here in full: “ Stauffer et al (1997) diagnosed Metriaclima, and this diagnosis was expanded by Konings and Stauffer (2006). Condé and Géry (1999) claimed that Metriaclima should be regarded as a junior synonym of Maylandia Meyer and Foerster (1984), however, Meyer and Foerster (1984) failed to supply a character in which their subgenus Maylandia, defined by its type species M. greshakei, is distinct from Pseudotropheus. Characters were given for a so-called zebra complex but M. greshakei was not considered part of that complex. The subgenus was thus not diagnosed according to the requirements of Article 13.1.1 of the Code, and was therefore regarded a nomen nudum by Stauffer et al. (1997) and subsequent authors (Konings and Geerts 1999, Geerts 2002, Stauffer and Kellogg 2002).” This paragraph has been repeated, nearly word-for-word, in three subsequent papers that proposed new species of Metriaclima (Stauffer, 2018; Miller et al., 2021; Stauffer and Konings, 2023). Since there is no Article 13.1. 1 in the second (1964) nor third (1985) editions of the Code, it must be assumed that Stauffer is referring to the fourth edition (1999). Although this edition does not apply to Maylandia, the language of Article 13.1.1 is identical to that of the third edition and similar to that in the second: Names published after 1930 must “be accompanied by a description or definition that states in words characters that are purported to differentiate the taxon.” As demonstrated above, the original description of Maylandia is accompanied by such words.
Maylandia is an ICZN-available name that has priority over Metriaclima.
description: Published as part of Scharpf, Christopher, 2025, Scantily clad but not naked: an analysis of the Metriaclima vs. Maylandia (Teleostei: Cichlidae) debate, pp. 461-469 in Zootaxa 5620 (3) on pages 463-467, DOI: 10.11646/zootaxa.5620.3.5, http://zenodo.org/record/15219746