No. The soul and an angel are not of the same species because a separate form cannot be understood otherwise than as one of a single species.
Anima igitur et Angelus non sunt unius speciei. Non enim potest intelligi quod aliqua forma separata sit nisi una unius speciei.
In incorporeal substances there cannot be diversity of number without diversity of species and inequality of nature; because, as they are not composed of matter and form, but are subsistent forms, it is clear that there is necessarily among them a diversity of species.
In substantiis incorporeis non potest esse diversitas secundum numerum absque diversitate secundum speciem, et absque naturali inaequalitate. Quia si non sint compositae ex materia et forma, sed sint formae subsistentes, manifestum est quod necesse erit in eis esse diversitatem in specie.
One matter cannot be distinct from another, except by a distinction of quantity, which has no place in these incorporeal substances, such as an angel and the soul. So that it is not possible for the angel and the soul to be of the same species.
Nec poterit dici materia haec alia ab illa, nisi secundum divisionem quantitativam, quae non habet locum in substantiis incorporeis, cuiusmodi sunt Angelus et anima. Unde non potest esse quod Angelus et anima sint unius speciei.
How it is that there can be many souls of one species will be explained later (Q76, A2, RO1).
Quomodo autem sint plures animae unius speciei infra ostendetur.
The body is not of the essence of the soul; but the soul by the nature of its essence can be united to the body, so that, properly speaking, not the soul alone, but the "composite," is the species.
Corpus non est de essentia animae, sed anima ex natura suae essentiae habet quod sit corpori unibilis. Unde nec proprie anima est in specie; sed compositum.
And the very fact that the soul in a certain way requires the body for its operation, proves that the soul is endowed with a grade of intellectuality inferior to that of an angel, who is not united to a body.
Et hoc ipsum quod anima quodammodo indiget corpore ad suam operationem, ostendit quod anima tenet inferiorem gradum intellectualitatis quam Angelus, qui corpori non unitur.
Dionysius says (Div. Nom. vii), "Angelic minds have simple and blessed intelligence, not gathering their knowledge of Divine things from visible things."
Dicit Dionysius, VII cap. de Div. Nom., "mentes angelicae simplices et beatos intellectus habent, non de visibilibus congregantes divinam cognitionem".