Review History
Taxonomic revision of the Temnothorax salvini clade (Hymenoptera: Formicidae), with a key to the clades of New World Temnothorax

John Longino · Mar 16, 2021

Reviewer 2 · Mar 20, 2021

Additional comments

Dear Dr. Matthew M. Prebus,

I would like to congratulate the author for the initiative and hard work in conducting the Taxonomic Revision of the Temnothorax salvini Clade.

The manuscript provides a taxonomic revision of the salvini clade of ant genus Temnothorax, in which 35 new species are described and other nomenclatural acts are taken. The manuscript is complete and well-founded. In addition to taxonomic contributions, the manuscript provides insights into new issues to be investigated, such as the relationship between the size of the sting and the stratum that species occupy.

My comments are mainly focused on the structure of the species descriptions, on the standardization of small inconsistencies that I detected. My revision is available in the attached file.

My thanks to the author for his effort to make this taxonomic revision available to the scientific community.

Reviewer 3 · Mar 20, 2021

Additional comments

This is a species-level taxonomic revision of a large group of ants (Temnothorax salvini clade) occurring in the Nearctic and northern Neotropical regions. It is a notable accomplishment, treating the group carefully and comprehensively. This is essentially a taxonomic monograph—if PeerJ is open to publishing such large papers, then that is welcome. I have to say that, despite two attempts, I was unable to download the full complement of files. The zip file was too large, it seems. So, my review is based on examination of the main text of the paper and selected images (about 80 of them) that I downloaded individually.

I do not have any major criticisms of this study. It is a stellar contribution to Temnothorax systematics, and it stands as a model for modern, intelligently-executed, species-level taxonomy. Much of the recent taxonomic literature on ants consists of short papers describing one or two new species, without a broader synthetic overview, so it is a pleasure to see a really comprehensive treatment of a species-rich group, over a large geographical area. The work is grounded in detailed examination of morphological variation in a large sample of specimens, and backed up by an impressive molecular (phylogenomic) dataset. The paper is also copiously illustrated, with high quality specimen images and and distribution maps. The use of unique specimen identifiers is exemplary, as is database management of the specimens examined.

My main concern is a practical one: will this paper, with its full set of illustrations, be capable of being easily downloaded, and will it be kept to a reasonable size? Unlike other papers, for which online access is generally sufficient, there is a specific utility to having taxonomic papers available as offline copies. One might be in the field, for example, without internet access, and want to use the keys. Indeed, while I don’t want to devalue the detailed and careful species descriptions, let’s be honest: the parts of this paper that will be most frequently consulted by future users are the illustrated keys and the differentiating comments in the species accounts. So, I hope that in the production of this paper the issue of portability is kept in mind. This might require some discussion between PeerJ and the author—perhaps reducing the resolution of some images and having them available as high-resolution images in supplementary material.

I have quite a few other comments and corrections, but they are mostly minor and should be readily addressable.

In the Abstract (and References) you transcribe “Neotropical” in two different ways (capitalized and not). I would capitalize throughout.

Lines 44-46. The placement of the last phrase (“by evolutionary convergence”) leads to some ambiguity. Rewrite for clarity:
“…have arrived by evolutionary convergence at a morphological syndrome with characteristics that were used to diagnose the former genus Macromischa.”

Line 62. Change “longcaulis” to “longicaulis”.

Lines 100-101. Reposition “in”.

Line 112. Change “has” to “have”.

Line 163. Delete “in”.

Lines 164 et seq. The name “Palearctic clade” emphasizes that most members are found in that region, but it is a bit misleading in that the clade is actually Holarctic. I guess that the name is now entrenched, but “Holarctic clade” would have been a better moniker.

Line 175. Insert “of” after “majority”.

Line 178. For clarity change “certain species of the Mediterranean” to “certain species of the Mediterranean region of Europe” (if that is what you mean). See also line 6720.

Line 208. “ocarinae” is misspelled.

Line 209. Change “only known” to “known only”.

Lines 311-312. “Diagonal petiolar length in lateral view; measured from the junction between the apex of the subpetiolar process to the posterodorsal corner of caudal cylinder”.
This is confusing. What do you mean by “from the junction between to”? This would make more sense if the phrase “the junction between” was removed:
“Diagonal petiolar length in lateral view; measured from the apex of the subpetiolar process to the posterodorsal corner of caudal cylinder”.

Lines 314-316. The definition of NOL (petiole node length) is a bit odd. I think it would be better defined by the reference line that you describe in lines 318-320.

Lines 321-323. It is probably worth adding that this measurement of the length of the postpetiole excludes the helcium.

Lines 350-351 repeat lines 348-349.

Lines 388-389. “In case where coordinates were not given on the specimen labels, they were estimated from label data with Google Earth; these coordinates are provided in brackets, with a standard error of one minute.”
You cite decimal coordinates so it is curious that you here cite a standard error of “one minute”.

Lines 404 et seq. Please provide locations for collections BEBC and MMPC (even if they change in the future).

Line 429. BMNH is the more common (and better recognized) acronym for the Natural History Museum, London.

Line 533. You cite Fig. 12f as an example of a long node, yet the dashed lines in that figure signify a different aspect of node length than NOL (cf. Fig. 6f).

Lines 536, 539. Change “short a” to “a short”.

Lines 681-620. “The species groups used in this study correspond to morphologically diagnosable groups of species which are supported by molecular evidence from the studies mentioned above.”
It is a bit vague to just say “supported by molecular evidence”. Presumably you mean “supported as monophyletic groups”? It is worth being explicit about this.

Lines 623-763. The illustrated key to clades of New World Temnothorax is a great feature of this paper. I tried the key and it generally worked well. I can appreciate the challenges faced in making this key, especially distinguishing between the salvini clade and the hypervariable sallei clade.
I think that couplet 8 (lines 674-679) may cause some difficulties, however. Measurement of several obturator-like workers from Mexico, with broader postpetioles than Texas obturator, yielded PWI values of 150-154. Some additional characters may be needed at this couplet to direct the user to the obturator clade.

Line 676. Change “PW” to “PEW” (PW is pronotum width).

Line 698. “posterior of head with ten or more erect setae”.
Do you mean the posterior margin, as seen in full-face view, or some more vaguely defined posterior region?

Lines 783-1115. Key to species of the Temnothorax salvini clade.
I had little material available to test this key, but what I had went through the key smoothly.

In couplet 9 of the key, T. aztecoides is said to have the “anterior half of first gastral tergite lightly sculptured”. In contrast, the species diagnosis (p. 278) states that the “entire first gastral tergite” is sculptured (and this is said to be a differentiating feature from T. aztecus). The species description (p. 280) is different again. In any event, this character needs to be checked. The gaster appears to be smooth and shiny in at least some specimens referable to T. aztecoides (Fig. 152).

Line 1727. Change “acutispinosus” to “altinodus”.

Line 1856. Change “five species (four of which are described here)” to “five species (four of which are newly described here)” because you do describe the fifth species.

Lines 1873-1874. In this and other lectotype designations, it is worth bolding the word “lectotype”, to make the action more obvious. I.e.,
“Syntype workers. Cuernavaca, Mexico. One worker here designated <b>lectotype</b>.”

Line 2860. Change “dead stalk of an aster” to “dead stalk of Asteraceae” (cf. line 3219).

Lines 2874-2875. This cannot be a syntype gyne (and therefore a paralectotype) because Forel’s (1901d) original description refers to workers only.

Line 2876. Macromischa is misspelled.

Lines 2878-2880. Leptothorax augusti was a replacement name for Leptothorax foreli (Aguayo) (nec Leptothorax foreli Santschi), not a replacement name for Macromischa petiolata Forel.

Line 4254. Correct the misspelling of “distribution”.

Line 4255. Change “may be revealed” to “it may be revealed”.

Line 4614. Specify the caste of the syntype selected as lectotype.

Line 5107. Change “examined” to “examine”.

Line 6018. Elsewhere in the manuscript this section, which provides information on distribution and biology, is titled “Comments”. For consistency do the same here.

Line 6271 Insert “of” after “inspection”.

Lines 6713-6720. In introducing the pergandei group, it seems worth mentioning that for a long time the nominate species was placed in its own subgenus (Dichothorax).

Lines 7985-7986. It seems questionable to interpret a Winkler sample as a “nest collection”.

Line 8694. Change “which are known” to “which is known”.

Lines 8694-8696. You seem to be saying that T. flavidulus is known only from the types collected off the northern coast of the Dominican Republic, which is not true.

Line 8704. Out-of-place paragraph return.

Line 8921. Change “which are known” to “which is known”.

Lines 10492-10493. “…recovered all of the known specimens used in this study.”
For clarification insert “of T. wilsoni” after “known specimens”, if that is what you mean.

Line 19063. Change “discovered in” to “discovered”.

Lines 11276, 11278. Specify the castes of the syntypes selected as lectotypes (the information is provided later but it should be here too).

Line 11586. Correct misspelling of Isthmus.

Line 12403. What is the meaning of “Paratype worker gyne”? Should there be a comma after “worker”?

Lines 12607-12608. “The types of this species were found in dead twigs, live hollow stems, and by beating vegetation.”
It is a bit odd to speak of the “types” of this species, since there is only one primary type specimen. In any event, the holotype and two paratypes come from a single nest series, so the statement is inaccurate.

Line 12619. Change “Paratype workers” to “Paratype worker”, since there is only one.

Line 12948. Remove “made”.

Line 13317. Capitalize “mountains”.

Line 13980. Correct the misspelling of “generalized”.

Line 13892. Change “membership to” to “membership in”.

Line 14203. Correct the misspelling of “tricarinatus”.

Lines 14268-14269. “Zoology” is misspelled. Moreover, this should be cited as a serial (as you do for Wilson, 1955):
Bulletin of the Museum of Comparative Zoology 104:1–585.

Line 14291. Volume number is missing.

Line 14320. Capitalize “sociaux”.

Lines 14332-14334. Citation appears to be incomplete.

Lines 14357-14358. A doi is needed for this reference since “250” is the article number, not a page number. Also, “evolutionary” and “biology” should be capitalized.

Lines 14359-14361. Now that the final version of this paper has appeared, with volume and page numbers, it should be cited that way. I.e., Prebus (2021) Systematic Entomology 46:307-326. Be sure to replace Prebus (2020) with Prebus (2021) throughout the text.

Line 14386. Insert “of the” before “Entomological”.

Lines 14395-14440. There is some mix-up here. A paper with the same title, journal, volume, and page numbers is listed twice and with different years: Vásquez-Bolaños (2011) and Vásquez-Bolaños (2015b). Remove the duplicate (which is apparently the second one) and then check to see that the paper is properly cited in the text.

Lines 14397-14398. As cited, this paper has 523 pages. I think it should be:
Métodos en Ecología y Sistemática 10(1): 1-53.
If this is the only 2015 paper by Vásquez-Bolaños that you cite then it needs to be changed from 2015a to 2015.

Line 14406. Here you cite the journal as “Psyche (Cambridge)”, for other papers just “Psyche”. The former is preferable.

Lines 14413-14414 and 14417-14418. Wheeler & Mann (1914) is cited twice, slightly differently. The second one is the correct citation.